close

Вход

Забыли?

вход по аккаунту

?

j.dyepig.2018.08.029

код для вставкиСкачать
Accepted Manuscript
Trans-A2B2 Zn(II) porphyrin dyes with various donor groups and their Cosensitization for highly efficient dye sensitized solar cells
Kamal Prakash, Vediappan Sudhakar, Muniappan Sankar, Kothandam
Krishnamoorthy
PII:
S0143-7208(18)30668-5
DOI:
10.1016/j.dyepig.2018.08.029
Reference:
DYPI 6943
To appear in:
Dyes and Pigments
Received Date: 26 March 2018
Revised Date:
16 July 2018
Accepted Date: 19 August 2018
Please cite this article as: Prakash K, Sudhakar V, Sankar M, Krishnamoorthy K, Trans-A2B2 Zn(II)
porphyrin dyes with various donor groups and their Co-sensitization for highly efficient dye sensitized
solar cells, Dyes and Pigments (2018), doi: 10.1016/j.dyepig.2018.08.029.
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to
our customers we are providing this early version of the manuscript. The manuscript will undergo
copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please
note that during the production process errors may be discovered which could affect the content, and all
legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT
Trans-A2B2 Zn(II) Porphyrin Dyes with Various Donor Groups and their Co-sensitization
for Highly Efficient Dye Sensitized Solar Cells
RI
PT
Kamal Prakash, Vediappan Sudhakar, Muniappan Sankar and Kothandam Krishnamoorthy
AC
C
EP
TE
D
M
AN
U
SC
Four Trans-A2B2 porphyrin dyes (KP-Zn-BTP, KP-Zn-CBZ, KP-Zn-PYR and KP-Zn-PTZ) with different donors were
applied for photovoltaic application. The co-sensitization of these dyes with N719 dye improved their DSSCs efficiency
from η = 1.71-5.48% to 4.88-8.80% by increasing the light harvesting ability in Soret and Q band region. Phenotheizene
appended dye (KP-Zn-PTZ) exhibited maximum power conversion efficiency (η = 8.80%) as compared to other dyes due
to strong electron-donating ability and effective suppression of dye aggregation.
ACCEPTED MANUSCRIPT
Trans-A2B2 Zn(II) Porphyrin Dyes with Various Donor Groups and their Cosensitization for Highly Efficient Dye Sensitized Solar Cells
Kamal Prakash,a Vediappan Sudhakar,b Kothandam Krishnamoorthy*b and Muniappan Sankar*a
RI
PT
Abstract
M
AN
U
SC
We have designed and synthesized four donor-acceptor based trans-A2B2 Zn(II) porphyrin dyes with various donor moieties and
phenylcarboxy as acceptor group in three steps. Two strong electron-donating groups (carbazole, phenothiazine, pyrene and bisthiophene)
were attached to porphyrin core to enhance the photon absorption of dye molecules and phenylcarboxy acted as acceptor group on TiO2
surface. The alkyl chains present in KP-Zn-CBZ and KP-Zn-PTZ dyes is helpful to suppress the aggregation of dyes at the semiconductor
surface. The synthetic route of these dyes was facile, high yielded and three steps procedure which involved MacDonald condensation
followed by hydrolysis and Zn insertion. The absorption and emission bands of all four dyes were broadened and red shifted due to the
charge transfer from donor groups to porphyrin moiety. A wide range of power conversion efficiency was shown by dyes and the order of ƞ
was as followed KP-Zn-PTZ (5.48%) ˃ KP-Zn-PYR (3.38%) ˃ KP-Zn-CBZ (2.64%) ˃ KP-Zn-BTP (1.71%). Co-sensitization of
porphyrin dyes with N719 dye promoted the complementary absorption in visible region and put restriction on dye aggregation also which
improved the cell performance. Co-sensitized KP-Zn-PTZ with N719 dye showed the highest PCE efficiency up to 8.80% with a Jsc = 17.4
mA cm-2, Voc = 0.73 V and FF = 70% which was superior than individual co-sensitized Zn(II) porphyrin dyes and N719 dye alone (ƞ =
7.3%).
1. Introduction
AC
C
EP
TE
D
World’s energy sources are heavily dependent on the fossil fuels such as coal, oil and natural gas whereas these fossil fuels are non
renewable which will be reduced by the time. These energy sources are also not environmental friendly and emit greenhouse gas CO2 that
causes climate change on the earth. Hence, the development of renewable energy sources such as solar energy, hydropower and biodiesel
became more necessary to ensure the energy securities with reducing the greenhouse emission as well as economically beneficial. Solar
energy is most promising renewable energy source as it is readily available and does not harm the environment. Silicon based solar cells are
mainly used to harness solar energy but its production cost is high and limits their vast application. Dye-sensitized solar cells technology
empowers the renewable energy source as a potential candidate for clean energy source due to its ecofriendly nature, low production cost and
large scale development.1-4 The efficiency of DSSCs relies upon photosensitizer used in the cell device which is a key component of the
cell.5 From 1991, tremendous effort has been made to develop highly efficient DSSCs by using different types of photo-sensitizers e.g.
ruthenium based dyes, organic dye and porphyrin dyes.6-9 Due to the rare availability, higher cost and environmental issues with ruthenium
based dyes, metal free organic dyes and zinc porphyrin sensitizers have attracted much more attention for researchers.10,11 Lot of organic
dyes showed good power conversion efficiency for DSSC. However, porphyrin molecules are found to be most favorable candidate for this
purpose due to their highly π-conjugated system, distinct physiochemical properties, intense absorption of sunlight and easy modification in
molecular structure.12,13 As compared to Ru complexes, simple tetraphenylporphyrin based dyes exhibited lower power conversion efficiency
for DSSCs as their light harvesting ability is not sufficient. The adsorption of dye on TiO2 via anchoring group and steric hindrance of
substituents also play important role to minimize the efficiency of the cell.10, 14-16 So, porphyrin structures were molecular engineered by
attaching bulky group and various type of donor/acceptor groups at periphery of porphyrin to minimize the effect of dye aggregation as well
as enhance the light harvesting ability.13-19
The nature and binding mode of anchoring group of sensitizers on TiO2 greatly affect the cell performance of the device.20,21 The presence of
carboxylic acid leads to higher dye loading on TiO2 surface than other groups such as phosphonic and pyridine groups.22-25 D’Souza et al and
He et al investigated different type of dye orientation on TiO2 surface and suggested that carboxy group is a better anchoring group at para
position than meta-position.26,27 Bulky peripheral substituents such as mesityl group or long alkoxy chains suppress the porphyrin dye
aggregation and displayed the higher power conversion efficiency.28,29 The wrapping of long ortho-alkoxy chains around the porphyrin ring
effectively reduce the aggregation of dye molecules and also retard the charge recombination process.30 The attachment of strong electron
donor on porphyrin core enhances the light harvesting ability in visible region. Imhori and coworkers introduced multiple diarylamino groups
into the porphyrin core to enhance their light harvesting ability.31 Since the development of donor-π-acceptor porphyrin structures to improve
the DSSC efficiency, many push-pull porphyrin sensitizers with different donor groups were reported till date.32-34 In a D-π-A system, charge
transfer occurs from donor to acceptor moiety and develops a charge separated species to efficient electron ejection. 35 A series of YD05,11,12,13,19 were reported with a varying of bulky/donor group that showed PCE of 1.76-6.79%.36,37 Acene (LAC1-5), fluorene (LD22)
and pyrene (LD4) substituted push pull porphyrin dyes showed higher PCE value ƞ = 5.5-10%.38-40 The fusion or annulations of porphyrins
with aromatic compounds improved the light harvesting ability of dye by the expansion of spectral window in the visible and near IR region
1
ACCEPTED MANUSCRIPT
2. Results and Discussion
2.1 Synthesis and Characterization
M
AN
U
SC
RI
PT
but their large and planar structures cause more dye aggregation that lower their photovoltaic performances.41,42 The greater efficiency of
DSSCs device may also be achieved by using Co(II)/(III) electrolyte instead of I-/I3- electrolyte. Cobalt redox electrolytes have greater Voc
than I-/I3- electrolyte which improve the ƞ value. Porphyrin dye YD2-o-C8 showed higher ƞ value of 12% when Co(II)/Co(III) redox shuttle
was applied in DSSC cell.43 In 2014, Luo and coworkers reported N-annulated perylene substituted WW-5 and WW-6 porphyrin sensitizers
which showed ƞ ˃10% with Co(II)/(III) electrolyte.44 Co-sensitisation can be very useful to enhance the efficiency of DSSCs cell by mixing
of two or more different dyes. A number of reports published on co-sensitized porphyrin dyes with organic dye to show the better cell
performance over the single dye molecule. 2,4-ZnP-CN-COOH porphyrin was co-sensitized with organic dye HC-A1 which displayed a
greater ƞ value of 8.4% as compared to independent porphyrin dye which have PCE efficiency of 4.9%.45 Xie and coworkers studied the cosensitization of XW4 porphyrin dye with an anthracenyl substituted dye C1 that showed PCE value of 8%.46 The cooperation of organic dye
with porphyrins not only enhances the light harvesting ability due to absorption bands of organic dye around 500 nm and their dye but their
bulky nature also suppress the dye aggregation.47-50 Recently, Kim et al designed two Zn(II) porphyrin sensitizers SGT-020 and SGT-021 by
appending bulky diphenylamine donor group (enhancement of Voc ) and triple bonded benzothiadiazole acceptor moiety (enhancement of Jsc)
to porphyrin core and they overall displayed power conversion efficiency of 10.5 and 12.4% respectively.51 In most cases, the synthesis of
highly efficient porphyrin dyes (more than 5-6%) was achieved by multistep procedure with lower yields and also involved the Pd-catalyzed
coupling reaction such as Stille couling, Suzuki coupling that leads to higher production cost of the DSSCs.45-51 Therefore, cost-effective
methods of dye synthesis are needed for the industrial production of dyes. In this work, we reported four trans-A2B2 Zn(II) porphyrin dyes
with various donor groups (carbazole, phenothiazine, pyrene and bisthiophene) and studied their photovoltaic application along with their
photophysical and electrochemical properties. Electron-donating groups increased the light harvesting ability of porphyrin dyes and
improved their photovoltaic performance. Co-sensitization of these dyes enhanced their PCE efficiency and phenothiazine appended dye
exhibited better efficiency as compared to others due to its strong electron-donating nature and butterfly conformation which suppress the
dye-aggregation problem.
AC
C
EP
TE
D
Trans-A2B2 Zn(II) porphyrin dyes were synthesized using modified literature methods as shown in scheme 1.28,52 The synthetic route of
these dyes involved three steps: (i) modified MacDonald condensation of 5-(4-carbomethoxyphenyl)dipyrromethane and different types of
aldehyde in presence of TFA to form trans-A2B2 diester porphyrins; (ii) hydrolysis of diester porphyrins into trans-A2B2 diacid porphyrins
and (iii) Zn metallation of diacid porphyrins to get desired Zn(II) trans-A2B2 porphyrin dyes. The first step of this synthesis not only
produced trans-A2B2 diester porphyrin but also formed other porphyrins due to scrambling process. The desired porphyrin was eluted as
second fraction. The condensation between 1-pyrenecarboxaldehyde and dipyrromethane afforded mostly trans-product which was purified
by column chromatography. The yields of the trans-A2B2 diester porphyrins were found 7-10%. Further, base hydrolysis of diester
porphyrins was performed to afford trans-A2B2 diacid porphyrins. Trans-A2B2 diacid porphyrins were obtained in 80-90% yield. Then, Zn
metallation of free base trans-A2B2 diacid porphyrins was proceeded to get desired Zn(II) trans-A2B2 porphyrin dyes with 90-95% yield. The
detailed synthetic procedure was described in experimental section in supporting information. Trans-A2B2 porphyrin dyes were further
characterized by UV-visible and fluorescence spectroscopic techniques, CHN analysis, DFT and photovoltaic studies. 1H NMR spectra of
diester and diacid porphyrins were recorded in CDCl3 and DMSO-d6, respectively at 298K in figure S1-S7 in supporting information (ESI).
Zn(II) porphyrin dyes are mostly insoluble in CDCl3 and had very low solubility in other deuterated solvents such as DMSO-D6, CD3OD-d6
etc. Hence, their NMR spectra could not be recorded. The other spectroscopic techniques (UV-vis, fluorescence spectroscopy) and MALDI
mass spectrometry analysis confirmed the synthesis of targeted Zn(II) porphyrin dyes. The MALDI-TOF mass spectra of all porphyrins were
shown in figures S8-S19 in SI.
2
M
AN
U
SC
RI
PT
ACCEPTED MANUSCRIPT
Scheme 1. Synthetic route for all synthesized trans-A2B2 Zn(II) porphyrin dyes.
2.2 Electronic Spectral Studies
The absorption spectra and emission spectra of trans-A2B2 Zn(II) porphyrin dyes were recorded in dichloromethane at 298K and their data is
also summarized in table 1. The absorption spectra of dyes are represented in fig 1a.
Table 1. Absorption and Emission data of trans-A2B2 Zn(II) porphyrin dyes.
KP-Zn-PTZ
Pyrene
KP-Zn-PYR
Carbazole
KP-Zn-CBZ
Bisthiophene
KP-Zn-BTP
Emission data, λmax, nm Quantum yield (фf)*
428 (5.71), 559 (3.59), 602 (3.36)
618, 659
0.036
430 (5.35), 555 (4.13)
610, 659
0.024
430 (5.52), 561 (4.22), 600 (3.98)
617, 659
0.026
432 (5.23), 559 (4.10), 605 (3.83)
631
0.033
EP
Phenothiazine
Absorption bands, λmax, nm (log ε in dm3
mol-1 cm-1)
TE
D
Donor Group Zn(II) Porphyrin dyes
*Error in quantum yield measurement is ±0.0005-0.001.
AC
C
The absorption spectra of trans-A2B2 dyes exhibited one Soret band around 428-432 nm and two Q bands in the range of 555-605 nm. The
Soret band of Zn dyes were 6-10 nm red shifted as compared to ZnTPP. The molar absorption coefficients of porphyrin dyes were higher and
their full width half maxima (FWHM) vary from 15 to 23 nm. Apart from the Soret and Q bands, Zn porphyrin dyes exhibited small
absorption bands from 220 to 350 nm which correspond to the donor moieties appended on the porphyrin core. Pyrene, carbazole and
phenothiazine appended porphyrins exhibited the small donor bands in the range of 200-300 nm whereas bisthiophene appended porphyrins
exhibit one broad donor band ranged from 300 to 350 nm. The donor substituent append on the porphyrin macrocycle have strong electrondonating ability and also make the porphyrin ring electron rich.
The emission spectra of trans-A2B2 dyes were recorded in dichloromethane at 298 K and presented in figure 1b. KP-Zn-CBZ and KP-ZnPTZ showed emission spectra around 617 nm with a shoulder band at 659 nm. The emission bands of KP-Zn-PYR appeared at 610 and 659
nm. KP-Zn-BTP dye exhibited only one emission band at 631 nm which is 14-21 nm bathochromically shifted as compared to other dyes.
The emission spectra of all dyes are much broader and 10-20 nm red shifted relative to ZnTPP. The quantum yields of Zn porphyrin dyes
were also calculated by comparative method considering ZnTPP as standards. The emission intensity and quantum yield of these Zn
porphyrin dyes are lower. The quantum yields are given in table 1. The order of quantum yields of dyes are as followed: KP-Zn-PYR < KPZn-CBZ < KP-Zn-BTP < KP-Zn-PTZ. So, the red shifted as well as broader absorption and emission spectra of dyes depicted that donor
moieties enhanced light harvesting ability of the porphyrin macrocycles. The quenching of fluorescence spectra and fluorescence
enhancement showed the possible intramolecular charge transfer from donor moieties to porphyrin macrocycle.53-55
3
SC
RI
PT
ACCEPTED MANUSCRIPT
M
AN
U
(a)
(b)
Figure 1. (a) Absorption spectra and (b) emission spectra of trans-A2B2 Zn(II) porphyrin dyes in CH2Cl2 at RT.
2.3 DFT Studies
AC
C
EP
TE
D
To understand the structural and electronic aspects of trans-A2B2 Zn(II) porphyrin dyes by appending the different donors, density functional
theory (DFT) calculations were performed using as B3LYP /6-31g (d) as basis set.56 The frontier molecular orbitals (HOMO, HOMO – 1,
LUMO and LUMO + 1) of all porphyrin dyes were shown in fig 2. For porphyrin dyes, all donor moieties as well as carboxyphenyl acceptor
groups are almost perpendicular to porphyrin plane. The phenothiazine moiety occupied the butterfly conformation in KP-Zn-PTZ dye and
reduces the dye aggregation with porphyrin molecules which is in good agreement with reported literature.57,58 The alkyl chains of KP-ZnPTZ and KP-Zn-CBZ also help to minimize the aggregation process. The distribution of electron density on HOMOs and LUMOs describe
charge separation in a porphyrin macrocycle and help to understand the electron transfer in porphyrin system. According to the molecular
orbitals of dyes, the electron density of HOMO and HOMO -1 is mostly spread over the donor moieties and porphyrin whereas LUMO and
LUMO+1 are spread over the porphyrin and carboxyphenyl acceptor group. The distribution of electron density of HOMOs and LUMOs
suggested the electron transfer from donor to porphyrin core and generation of effective charge separation system in the porphyrin molecule.
This charge separation further facilitates the electron ejection from dyes to TiO2 conduction bands which indicates that these dyes are suitable
for DSSC application. The simulated absorption spectra of dyes were shown in figure S20-S23 in ESI. Table S1 in ESI listed the simulated
absorption bands of all dyes which are consistent with their experimental data. For all dyes, the most intense absorption band appeared
around 400-408 nm and the absorption bands for first excitation S0 to S1 (S1) appeared in the range of 500-600 nm. Both KP-Zn-BTP and
KP-Zn-PYR dyes, the Soret band were found due to the transition from HOMO – 4 to LUMO + 4, both localized on porphyrin core and
appeared at 400 and 406 nm with as oscillator strength of 0.4976 and 0.6440 respectively. In case of KP-Zn-PTZ and KP-Zn-CBZ, the
Soret band appeared at 408 nm with an oscillator strength of 0.4875 and 0.4143 respectively and it was a π-π* transition from HOMO to
LUMO + 3and HOMO – 6 to LUMO respectively. The HOMO and HOMO-6 orbitals localized on donor and porphyrin moiety respectively
whereas LUMO + 3 and LUMO were distributed over porphyrin and carboxyphenyl moieties respectively indicating the effective charge
transfer process. In addition to Soret and Q bands in TD spectra, additional bands were observed in the range of 430-510 nm region. These
additional bands can also be ascribed as charge transfer excitation from donor to acceptor moiety. The results obtained from the DFT and
TD-DFT studies were in good agreement with experimental data and reported literature.30,50,59,60
4
ACCEPTED MANUSCRIPT
RI
PT
KP-ZnPTZ
M
AN
U
SC
KP-ZnPYR
TE
D
KP-ZnCBZ
EP
KP-ZnBTP
HOMO – 1
HOMO
LUMO
LUMO + 1
AC
C
Fig. 2. Frontier molecular orbitals (HOMO, HOMO – 1, LUMO and LUMO + 1) of Zn(II) Porphyrin dyes obtained by DFT optimization
with B3LYP/6-31G.
2.4 Electrochemical Redox Properties
The electrochemical studies of Zn(II) porphyrin dyes were performed to investigate the effect of the donor substituents on porphyrin rings
and also determine HOMO-LUMO gap for Zn(II) dyes. Cyclic voltammograms of trans-A2B2 porphyrin dyes were measured in dry THF
containing 0.1 M TBAPF6 under inert atmosphere at 298K. The Cyclic voltammograms of Zn(II) porphyrin dyes (KP-Zn-BTP, KP-ZnCBZ, KP-Zn-PYR and KP-Zn-PTZ) were shown in figure 3a and their redox potentials were summarized in table 2. KP-Zn-PYR, KP-ZnCBZ and KP-Zn-PTZ dyes exhibited two reversible oxidations and one reduction waves whereas KP-Zn-BTP showed only one oxidation
and one reduction processes. The redox potentials of all porphyrin dyes were anodically shifted as compared to the redox potentials of
ZnTPP. The first oxidation potentials of porphyrinic dyes were in the range of 0.86 to 1.10V and first reduction potentials were found in the
range of -1.10 to -1.36V. The oxidation potential of KP-Zn-BTP is observed at 1.10 V and more anodically shifted as compared to other
porphyin dyes and ZnTPP that can be ascribed due to the presence of bisthiophene moiety. The reduction potential of KP-Zn-PYR appeared
at -1.36 V similar to ZnTPP and cathodically shifted as compared to other dyes. The presence of two donor moieties on porphyrin core
5
ACCEPTED MANUSCRIPT
makes these dyes electron rich and difficult for reduction process. Hence, only one reduction potential was observed for these dyes. The first
ring redox potentials of KP-Zn-PTZ dye was cathodically shifted as compared to other dyes such as KP-Zn-BTP and KP-Zn-CBZ which
suggest that it can ease for oxidation process and suitable for photovoltaic application.
0.86
1.14
2.14
KP-Zn-PYR
1.09
1.31
2.19
KP-Zn-CBZ
0.92
1.29
2.28
KP-Zn-BTP
1.10
-
2.28
-1.28
-
-1.10
-
-1.36
-
-1.18
-
SC
KP-Zn-PTZ
RI
PT
Table 2. Electrochemical data (in V vs Ag/AgCl) of trans-A2B2 porphyrin dyes in CH2Cl2 containing 0.1 M TBAPF6 with a scan
rate of 0.1 V/s at 298 K.
Zn(II) porphyrin dyes
Oxidation (V)
∆E(V)
Reduction(V)
I
II
I
II
AC
C
EP
TE
D
M
AN
U
The difference between the first oxidation and reduction potentials described about the energy required for electronic transistion from
HOMO to LUMO energy level. The HOMO-LUMO energy gap of these dyes was obtained from electrochemical values and summarized in
table 2. The comparison of HOMO and LUMO energy levels of these porphyrins dyes with conduction band of nanocrystalline TiO2 and the
HOMO of I-/I3-electrolyte is depicted in figure 2b. As shown in figure 2b, the conduction band of TiO2 is lower than LUMOs of Zn(II)
porphyrin dyes and the HOMO of I-/I3- electrolyte is higher than HOMOs of dyes revealed that there will be facile electron transfer from the
excited dye to TiO2 and regeneration of porphyrin dye through I-/I3-electrolyte is also an easy process. The energy level diagram depicts the
feasibility of electron transfer in DSSC cell.
(a)
(b)
Fig. 3 Cyclic voltammograms of (a) Zn(II) porphyrin dyes in CH2Cl2 containing 0.1 M TBAPF6 with a scan rate of 0.1 V s-1 at 298K and (b)
Energy level diagram of dyes and comparison with nanocrystalline TiO2 and I-/I3-electrolyte.
2.5 Photovoltaic Studies
To perform the photovoltaic studies, DSSC cells were fabricated with trans-A2B2 porphyrin dyes appended a thick (12 µm) layer TiO2
photoanodes (0.16 cm2) and assembled it into standard sandwiched cells containing the Pt sheets counter electrode. I-/I3- electrolyte was filled
between the photoanodes as redox electrolyte. The detailed device fabrication is explained in the supporting information. The I-V spectra and
IPCE action spectra of trans-A2B2 porphyrin dyes were plotted in figure 4. As shown in figure 4a, The photocurrent spectra of these dyes
resemble with the absorption spectra of corresponding dye indicating the light harvesting in their Soret and Q bands region. The spectral
6
ACCEPTED MANUSCRIPT
M
AN
U
SC
RI
PT
responses of these dyes in IPCE action spectra were broader and red shifted which depicted the enhanced light harvesting ability of the dyes.
The IPCE spectra consisted of one maxima in the range of 425-435 nm and two weaker bands at 525 and 625 nm. KP-Zn-PTZ dye showed
highest 60% IPCE value at the wavelength of 425 nm and more than 15% IPCE in the range of 500-600 nm. Similarly, KP-Zn-PYR dyes
showed above 40% IPCE at Soret band and nearly 10% at the wavelength of Q bands region in IPCE spectra whereas KP-Zn-CBZ and KPZn-BTP showed only 30% and 20% at the wavelength of 425 nm in IPCE action spectra, respectively. The highest IPCE value of KP-ZnPTZ dye can be attributed to the presence of phenothiazine group having strong electron-donating ability as well as more absorption of light
in visible region.57,58,61,62 The onset wavelength for all dyes in IPCE spectra was at 750 nm. The increasing order of IPCE of the trans-A2B2
Zn(II) porphyrin dyes was as followed KP-Zn-BTP < KP-Zn-PYR < KP-Zn-CBZ < KP-Zn-PTZ.
(a)
(b)
Fig. 4 (a) IPCE spectra and (b) I-V characteristics of trans-A2B2 porphyrin dyes.
EP
0.55
0.57
0.61
0.62
0.64
0.68
0.72
0.73
0.71
AC
C
KP-Zn-BTP
KP-Zn-CBZ
KP-Zn-PYR
KP-Zn-PTNZ
KP-Zn-BTP/N719
KP-Zn-CBZ/N719
KP-Zn-DPY/N719
KP-Zn-PNZ/N719
STD-N719 (ref)
TE
D
Table 3. Photovoltaic parameters of trans-A2B2 Zn(II) porphyrin dyes under AM 1.5G sun illumination (power 100 mW cm2)
with an active area of 0.235 cm2.
Zn(II) Porphyrin dye
Voc (V)
Jsc (mA/cm2 )
FF (%)
η (%)
2.6
4.4
6.1
7.8
11.0
12.5
13.9
17.4
14.8
70
69
71
70
70
73
72
70
70
1.71±0.24
2.64±0.18
3.38±0.19
5.48±0.22
4.88±0.20
6.20±0.23
7.17±0.21
8.80±0.31
7.30±0.35
The current-voltage curves (J-V characteristics) of the DSSCs based on synthesized dyes (KP-Zn-BTP to KP-Zn-PTZ) are shown in Figure
4b and the corresponding photovoltaic parameters under AM 1.5G solar light illumination (power 100 mW cm-2) with an active area of 0.235
cm2, is listed in Table 3. The power conversion efficiencies of these dyes were obtained from 1.71 to 5.48%. KP-Zn-BTP showed only
1.71% power conversion efficiency with a Voc of 550 mV, Jsc of 2.6 mA cm-2 and a fill factor (FF) of 70%. KP-Zn-CBZ dye exhibited 2.64%
PCE efficiency that is lower than KP-Zn-PYR dye which exhibited 3.38% efficiency. It is shown in table 3 that the Voc and Jsc value is
greater for KP-Zn-PYR than KP-Zn-CBZ which indicate the more light harvesting from pyrene moiety and suppression of charge
recombination process in KP-Zn-PYR that enhance efficiency of the dye. As compared to all trans-A2B2 Zn porphyrin dyes, KP-Zn-PTZ
showed greater photovoltaic performance upto 5.48% with a Voc of 640 mV, Jsc of 11.9 mA cm-2 and a fill factor (FF) of 72%. Nonplanar
butterfly conformation of phenothiazine moiety and the presence of alkyl group retard the charge recombination and inhibit dye aggregation
on porphyrin molecules, thus PCE efficiency was improved with higher Voc and Jsc values. The efficiency of dyes was increased from
bisthiophene to phenothiazine group as follows KP-Zn-BTP (η = 1.71%) < KP-Zn-DPY (η = 2.64%) < KP-Zn-CBZ (η = 3.38%) < KPZn-PTZ (η = 5.48%) which indicate that as the electron-donating power of the donors increased, their light harvesting ability also increased
7
ACCEPTED MANUSCRIPT
M
AN
U
SC
RI
PT
and subsequently improved their photovoltaic performance. The efficiency of porphyrin dyes generally depends on two factors; (i) the
presence of donor moiety and (ii) the presence of Bulky group such as mesityl, tert. Butyl and alkoxy groups.12-16,63-67 Strong donor moieties
enhance the light harvesting ability and more charge transfer occur from donor to porphyrin core68 whereas Bulky group suppress the dye
aggregation within the molecules as well as retard the charge recombination process in DSSC cell.69 These both factors drastically enhanced
the photovoltaic performance of the dyes. In our trans-A2B2 Zn(II) porphyrin dyes, the light harvesting ability was enhanced by appending
two donor group whereas the presence of two carboxyphenyl group or the absence of any bulky group was not helpful to suppress the dye
aggregation of porphyrin molecules. So, these dyes showed PCE efficiency upto 5.48% only which is due to the dye aggregation through
hydrogen bonding between carboxylic acids and charge recombination issues.
(a)
(b)
Fig. 5 (a) IPCE spectra and (b) I-V spectra of N719 co-sensitized trans-A2B2 Zn(II) porphyrin dyes.
AC
C
EP
TE
D
To further improve the efficiency of trans-A2B2 porphyrin dyes, we have co-sensitized the dyes with complementary organic dye N719 and
their I-V curves and IPCE spectra were represented in figure 5. As seen in fig 4a, the IPCE spectra of trans-A2B2 dyes exhibited less than
20% at the wavelength of Q bands which suggested the light absorption of these dyes at the wavelength of Q bands is lesser than Soret band
that have upto 60% IPCE. It can be seen from figure 5a, the IPCE action spectra of N719 co-sensitized trans A2B2 porphyrin dyes showed
55-80% IPCE at the wavelength of 425 nm and 35-70% at the wavelengths of Q bands region. The co-sensitization of these dyes improves
the light harvesting in Soret and Q band region that leads to the higher efficiency of these dyes.70-74 The J-V curve of co-sensitized transA2B2 dyes is displayed in Figure 5b and corresponding photovoltaic parameters were summarized in table 3. The co-sensitization of dyes
drastically improved their photovoltaic performance from the PCE efficiency of 1.71-5.48% to 4.88-8.80%. The co-sensitization of KP-ZnBTP showed 56% and 37% IPCE at the wavelength of 425 and 500-600 nm respectively and nearly tripled their power conversion efficiency
by increasing from 1.71 to 4.88% with higher Jsc (11.0 mA cm-2). The co-sensitization of KP-Zn-CBZ and KP-Zn-PYR dye with N719 dye
improved their PCE efficiency upto 6.20 to 7.17% which is doubled from their individual photovoltaic performance (2.64 and 3.38%,
respectively). N719 co-sensitized KP-Zn-PYR and KP-Zn-CBZ dye exhibited almost similar IPCE value (65% and 63% respectively) at
the wavelength of 425 nm but KP-Zn-CBZ showed lower IPCE (35%) as compared to KP-Zn-PYR (65%) at the wavelength of 500-600 nm
that also lowered the PCE efficiency of co-sensitized KP-Zn-CBZ dye as compared to KP-Zn-PYR dye. As shown in IPCE spectra, the cosensitization of KP-Zn-PTZ dye gave more than 70% IPCE value and highest PCE efficiency upto 8.80% was obtained with highest Jsc
(17.4 mA cm-2) and Voc (730 mV). The N719 dye itself exhibited PCE efficiency of 7.30% when similar experimental conditions were
applied. After co-sensitization, the PCE of KP-Zn-PTZ dye was improved 21% more than the efficiency of N719 dye and 61% improved as
compared to individual KP-Zn-PTZ dye. These results confirmed the co-sensitization of trans-A2B2 porphyrin dyes enhanced their
photovoltaic performance from the individual dye performance due to the increment in light harvesting by complementary N719 dye in Q
bands region (500-600 nm) of these dyes. The increased Jsc and Voc values of co-sensitized dyes suggest that the co-sensitization of the dyes
also reduced the dye aggregation and slow the charge recombination process.
2.6 Electrochemical Impedance Spectroscopy (EIS)
For the better explanation of the photovoltaic behavior of trans-A2B2 porphyrin dyes, electrochemical impedance spectroscopy (EIS) studies
were performed under a bias voltage of -0.5 V in dark condition. EIS measurements can give valuable information to understand unusual
photovoltaic parameters such as Jsc, Voc and η of DSSC studies.75-77 The EIS Nyquist plot of trans-A2B2 porphyrin dyes is displayed in fig 6a.
8
ACCEPTED MANUSCRIPT
(b)
EP
(a)
TE
D
M
AN
U
SC
RI
PT
The larger semicircle observed in middle frequency region depicts the resistance (Rct) against charge recombination process at the interface
of TiO2-dye-electrolyte.78 Greater Rct value means the reverse transfer of the injected electron from the TiO2 to electrolyte is more difficult,
so charge recombination rate become slower and Voc will be increased accordingly.79 It is observed from the figure S24a that KP-Zn-PTZ
dye exhibited largest Rct value (60 Ω) as compared to other dyes and had highest Voc (620 mV) than other dyes. The bulky nature of
phenothiazine moiety and presence of alkyl chain effectively suppress the charge recombination process.57,58 The Rct of KP-Zn-PYR and
KP-Zn-CBZ were found to be 40 Ω and 29 Ω respectively and their corresponding Voc value were 610 mV and 570 mV. The lowest Voc
value of 550mV was observed for KP-Zn-BTP dye corresponding to Rct value of 29 Ω. At a given voltage, the order of fitted Rct of transA2B2 porphyrin dyes is: KP-Zn-PTZ > KP-Zn-DPY > KP-Zn-CBZ > KP-Zn-BTP which is consistent with the Voc values and also
confirmed the correlation of Rct and Voc. The Voc of DSSCs device is mainly related to charge recombination process (Rct) and the shift in the
TiO2 conduction band (Ecb), which can be ascribed as chemical capacitance (Cµ).49,50,80-82 From the Rct and Cµ (figures S24a and S25a in
ESI), the electron lifetime can be determined by using the equation, τ = Rct Cchem.83,84 The electron lifetime (τ) is plotted against the bias
voltage in figure 7a. The longer lifetime of dye depicts the effectively suppression of back reaction of injected electron to the electrolyte and
leads toward the higher Voc.43,51 At a given bias voltage, the electron lifetime (τ) lies in the order of KP-Zn-PTZ > KP-Zn-DPY > KP-ZnCBZ > KP-Zn-BTP. At a given voltage, KP-Zn-PTZ dye demonstrated higher value of Cµ than other dyes which depicts downward shift in
TiO2 conduction band edge and tend to decrease the Voc of the dye but larger Rct (60 Ω) value and longer electron lifetime (45 ms) suppressed
the charge recombination which caused the rise the Voc and KP-Zn-PTZ finally afford the slightly higher Voc. Thus, the higher efficiency of
KP-Zn-PTZ dye is obtained by the effective light harvesting ability of donor group, suppression of dye aggregation and slower charge
recombination process rather than shift in TiO2 conduction band egde.
AC
C
Fig. 6 Nyquist plots for (a) Zn(II) porphyrin dyes (KP-Zn-BTP to KP-Zn-PTZ) and (b) N719 co-sensitized Zn(II)porphyrin dyes (KP-ZnBTP/N719 to KP-Zn-PTZ/N719) under forward bias voltage of -0.5 V in dark condition.
The EIS measurements for co-sensitized trans-A2B2 Zn(II) porphyrin dyes were also performed and the Nyquist plot of co-sensitized dyes
was shown in figure 6b. The radius of larger semicircle in middle semicircle increased which showed the increased efficiency of the cosensitized dyes. The plots of Rct and Cµ were shown in figure S24b and S25b in the SI, respectively. The electron lifetimes of co-sensitized
dyes were presented in figure 7b. The chemical capacitance (Cµ), interfacial charge resistance (Rct) and electron lifetime (τ) of co-sensitized
followed the same trend as shown for individual dyes. The higher values of Cµ for co-sensitized dyes indicated the positive shift of
conduction band of TiO2 which would lower the Voc of dyes. From the comparison of Rct values, it is found that the co-sensitization of the
dyes decreased the charge interfacial resistance, Rct, from the value of 29-60 Ω for individual dyes to 19-35 Ω for co-sensitized dyes. The
decrement in the Rct suggested that the back electron transfer from the TiO2 to electrolyte became faster i.e. more charge recombination than
individual dyes which would cause the decrement in Voc values. So, the observation of Rct and Cµ curve, it was observed that Voc of cosensitized should be lowered than individual dye. The electron lifetimes (τ) of the dyes were dramatically elongated after the co-sensitization
of dyes which can be termed as the enhancement of the light-harvesting ability with co-absorbent N719 dye and suppression of dye
aggregation of porphyrin molecules. As seen in IPCE spectra and I-V characteristics, the light harvesting ability of dyes in 500-600 nm
regions after co-sensitization with N719 dye is drastically enhanced. This enhancement in light harvesting was much larger that it reduced
9
ACCEPTED MANUSCRIPT
M
AN
U
SC
RI
PT
the effect of increased charge recombination and the downward shift of TiO2 conduction band edge and finally afforded improved Voc with
the higher Jsc value as shown in table 3 and better than the photovoltaic performance from individual dyes. These EIS measurements finally
showed that the PCE efficiency of co-sensitized dyes is mainly improved due to enhanced light harvesting ability of dye rather than the
charge recombination rates and the shift of the TiO2 conduction band edge.
(a)
(b)
Figure 7. Plots of electron lifetimes (τ) versus bias voltage of DSSCs based on (a) Zn(II) porphyrin dyes (KP-Zn-BTP to KP-Zn-PTZ)
and (b) N719 co-sensitized Zn(II)porphyrin dyes (KP-Zn-BTP/N719 to KP-Zn-PTZ/N719).
3. Conclusions
AC
C
EP
TE
D
In summary, four Zn(II) trans-A2B2 porphyrin dyes have been synthesized with different donors and carboxyphenyl as acceptor group by a
facile, high yield and Pd free methodology. Two electron-donor moieties were appended to porphyrin framework to enhance the light
harvesting ability to increase the photocurrent density, Jsc, for dye-sensitized solar cell. DFT studies showed the effective charge transfer
from donor moieties to acceptor that helps to eject electron from dye (excited state oxidation of dye) to TiO2 conduction band.
Electrochemical studies revealed the feasibility of electron transfer in DSSC cells. The power conversion efficiencies (η) of these dyes were
obtained in the range of 1.71%-5.48%. Among all, KP-Zn-PTZ dye exhibited higher photovoltaic performance up to 5.48% with a Voc of
640 mV, a Jsc of 11.9 mA cm-2 and a fill factor of 72% due to strong electron-donating ability of phenothiazine donor as well as the butterfly
conformation of donor group which impede the dye-aggregation and inhibit charge recombination. Co-sensitization enhance the light harness
of dyes in Soret (400-450 nm) and Q band region (530-650 nm) that increased Jsc value from 2.6-7.8 mA cm-2 to 11.0-17.4 mA cm-2 and
improved PCE efficiencies of 4.88-8.80% has been achieved. Co-sensitized KP-Zn-PTZ dye exhibited impressive highest efficiency of
8.80%.
Acknowledgements
The financial support has been provided by Science and Engineering Research Board (EMR/2016/004016) for research work. KP thanks
Ministry of Human Resource Development (MHRD), India for senior research fellowship (SRF).
a
Deparment of Chemistry, Indian Institute of Technology Roorkee, Roorkee - 247667, India. E-Mail: sankafcy@iitr.ac.in. Tel: +911332
284753; Fax: +91-1332-273560
b
Polymer and Advanced Material Laboratory, CSIR-National Chemical Laboratory, Pune-411008, India. E-Mail:
k.krishnamoorthy@ncl.res.in. Tel: +91-2025-903075; Fax: + 91-2025-902615.
10
ACCEPTED MANUSCRIPT
Notes and References
AC
C
EP
TE
D
M
AN
U
SC
RI
PT
1. B. O'Regan, M. Grätzel, A Low-Cost, High-Efficiency Solar Cell Based on Dye-Sensitized Colloidal TiO2 Films, Nature 353(1991) 737740.
2. Y. Z. Wu, W. H. Zhu, S. M. Zakeeruddin, M. Gratzel, Insight into D–A−π–A Structured Sensitizers: A Promising Route to Highly
Efficient and Stable Dye-Sensitized Solar Cells, ACS Appl. Mater. Interfaces 7(2015) 9307-9318.
3. M. Ye, X. Wen, M. Wang, J. Iocozzia, N. Zhang, C. Lin, Z. Lin, Recent Advances in Dye-Sensitized Solar Cells: from Photoanodes,
Sensitizers and Electrolytes to Counter Electrodes, Mater. Today 18(2015) 155-162.
4. M. Wu, M. Ma, Recent Progress of Counter Electrode Catalysts in Dye-Sensitized Solar Cells, J. Phys.Chem. C 118(2014) 16727-16742.
5. S. Zhang, X. Yang, Y. Numata, L. Han, Highly Efficient DyeSensitized Solar Cells: Progress and Future Challenges, Energy Environ.
Sci. 6(2013) 1443-1464.
6. Z. Ji, G. Natu, Y. Wu, Cyclometalated Ruthenium Sensitizers Bearing a Triphenylamino Group for π-Type NiO Dye-Sensitized Solar
Cells, ACS Appl. Mater. Interfaces 5(2013) 8641-8648.
7. K. T. Ngo, N. A. Lee, S. D. Pinnace, J. Rochford, Engineering of Ruthenium(II) Photosensitizers with Non-Innocent Oxyquinolate and
Carboxyamidoquinolate Ligands for Dye-Sensitized Solar Cells, Chem. Euro. J. 23(2017) 7497-7507.
8. M. Liang, J. Chen, Arylamine Organic Dyes for Dye-Sensitized Solar Cells, Chem. Soc. Rev. 42(2013) 3453-3488.
9. M. Urbani, M. Grätzel, M. K. Nazeeruddin, T. Torres, Meso-Substituted Porphyrins for Dye-Sensitized Solar Cells, Chem. Rev.
114(2014) 12330-12396.
10. L. Giribabu, R. K. Kanaparthi, Are Porphyrins an Alternative to Ruthenium(II) Sensitizers for Dye-Sensitized Solar Cells? Curr. Sci.
104(2013) 847-855.
11. C. L. Wang, C. M. Lan, S. H. Hong, Y. F. Wang, T. Y. Pan, C. W. Chang, H. H. Kuo, M. Y. Kuo, E. W. G. Diau, C. Y. Lin, Enveloping
Porphyrins for Efficient Dye-Sensitized Solar Cells, Energy Environ. Sci. 5(2012) 6933-6940.
12. S. Mathew, A. Yella, P. Gao, R. Humphry-Baker, B. F. E. Curchod, N. Ashari-Astani, I. Tavernelli, U. Rothlisberger, M. K.
Nazeeruddin, M. Gratzel, Dye-Sensitized Solar Cells with 13% Efficiency Achieved through the Molecular Engineering of Porphyrin
Sensitizers, Nat. Chem. 6(2014) 242-247.
13. T. Higashino, H. Imahori, Porphyrins as Excellent Dyes for Dye-Sensitized Solar Cells: Recent Developments and Insights, Dalton
Trans. 44(2015) 448-463.
14. L. L. Li, E. W. G. Diau, Porphyrin-Sensitized Solar Cells, Chem. Soc. Rev. 42(2013) 291-304.
15. A. Ö. Birel1, S. Nadeem, H. Duman, Porphyrin-Based Dye-Sensitized Solar Cells (DSSCs): a Review, J. Fluoresc. 27(2017) 1075-1085.
16. K. Ladomenou, T. N. Kitsopoulos, G. D. Sharma, A. G. Coutsolelos, The Importance of Various Anchoring Groups Attached on
Porphyrins as Potential Dyes for DSSC Applications, RSC Adv. 4(2014) 21379-21404.
17. A. Covezzi, A. O. Biroli, F. Tessore, A. Forni, D. Marinotto, P. Biagini, G. Di Carlo, M. Pizzotti, 4D–π–1A type β-Substituted ZnIIPorphyrins: Ideal Green Sensitizers for Building-Integrated Photovoltaics, Chem. Commun. 52(2016) 12642-12645.
18. T. Zhang, X. Qian, P. F. Zhang, Y. Z. Zhu, J. Y. Zheng, A Meso–Meso Directly Linked Porphyrin Dimer-based Double D–π–A
sensitizer for Efficient Dye-Sensitized Solar Cells, Chem. Commun. 51(2015), 3782-3785.
19. N. V. Krishna, J. V. S. Krishna, S. P. Singh, L. Giribabu, L. Han, I. Bedja, R. K. Gupta, A. Islam, Donor-π−Acceptor Based Stable
Porphyrin Sensitizers for Dye-Sensitized Solar Cells: Effect of π-Conjugated Spacers, J. Phys. Chem. C 121(2017) 6464-6477.
20. H. Imahori, S. Kang, H. Hayashi, M. Haruta, H. Kurata, S. Isoda, S. E. Canton, Y. Infahsaeng, A. Kathiravan, T. Pascher, P. Chábera, A.
P. Yartsev, V. Sundström, Photoinduced Charge Carrier Dynamics of Zn−Porphyrin−TiO2Electrodes: The Key Role of Charge
Recombination for Solar Cell Performance, J. Phys. Chem. A 115(2011) 3679-3690.
21. S. Ye, A. Kathiravan, H. Hayashi, Y. Tong, Y. Infahsaeng, P. Chabera, T. Pascher, A. P. Yartsev, S. Isoda, H. Imahori, V. Sundström,
Role of Adsorption Structures of Zn-Porphyrin on TiO2 in Dye-Sensitized Solar Cells Studied by Sum Frequency Generation Vibrational
Spectroscopy and Ultrafast Spectroscopy, J. Phys. Chem. C 117(2013) 6066-6080.
22. L. Zhang, J. M. Cole, Anchoring Groups for Dye-Sensitized Solar Cells, ACS Appl. Mater. Interfaces 7(2015) 3427-3455.
23. L. N. Yang, Z. Z. Sun, S. S. Chen, Z. S. Li, The Effects of Various Anchoring Groups on Optical and Electronic Properties of Dyes in
Dye-Sensitized Solar Cells, Dyes Pig. 99(2013) 29-35.
24. Y. Ooyama, N. Yamaguchi, I. Imae, K. Komaguchi, J. Ohshita, Y. Harima, Dye-Sensitized Solar Cells Based on D-π-A Fluorescent
Dyes with Two Pyridyl Groups as an Electron-Withdrawing-Injecting Anchoring Group, Chem. Commun. 49(2013) 2548-2550.
25. I. Lopez-Duarte, M. Wang, R. Humphry-Baker, M. Ince, M. V. Martínez-Díaz, M. K. Nazeeruddin, T. Torres, M. Grätzel, Molecular
Engineering of Zinc Phthalocyanines with Phosphinic Acid Anchoring Groups, Angew. Chem., Int. Ed. 124(2012) 1931-1934.
26. A. S. Hart, B. K. C. Chandra, H. B. Gobeze, L. R. Sequeira, F. D’Souza, Porphyrin-Sensitized Solar Cells: Effect of Carboxyl Anchor
Group Orientation on the Cell Performance, ACS Appl. Mater. Interfaces 5(2013) 5314-5323.
27. L. Si, H. He, Porphyrin Dyes on TiO2 Surfaces with Different Orientations: A Photophysical, Photovoltaic, and Theoretical Investigation,
J. Phys. Chem. A 118(2014) 3410-3418.
11
ACCEPTED MANUSCRIPT
AC
C
EP
TE
D
M
AN
U
SC
RI
PT
28. R. Kumar, M. Sankar, V. Sudhakar, K. Krishnamoorty, Synthesis and Characterization of Simple Cost Effective trans-A2BC Porphyrins
with Various Donor Groups for Dye-Sensitized Solar Cells, New J. Chem. 40(2016) 5704-5713.
29. T. Higashino, K. Kawamoto, K. Sugiura, Y. Fujimori, Y. Tsuji, K. Kurotobi, S. Ito, H. Imahori, Effects of Bulky Substituents of
Push−Pull Porphyrins on Photovoltaic Properties of Dye-Sensitized Solar Cells, ACS Appl. Mater. Interfaces 8(2016) 15379-15390.
30. G. Yang, Y. Tang, X. Li, H. Agren, Y. Xie, Efficient Solar Cells Based on Porphyrin Dyes with Flexible Chains Attached to the
Auxiliary Benzothiadiazole Acceptor: Suppression of Dye Aggregation and the Effect of Distortion, ACS Appl. Mater.
Interfaces 9(2017) 36875-36885.
31. K. Kurotobi, Y. Toude, K. Kawamoto, Y. Fujimori, S. Ito, P. Chabera, V. Sundström, H. Imahori, Highly Asymmetrical Porphyrins with
Enhanced Push–Pull Character for Dye-Sensitized Solar Cells, Chem. Eur. J. 19(2013) 17075-17081.
32. J. Lu, S. Liu, H. Li, Y. Shen, J. Xu, Y. Cheg, M. Wang, Pyrene-Conjugated Porphyrins for Efficient Mesoscopic Solar Cells: The Role of
the Spacer, J. Mater. Chem. A 2(2014) 17495-17501.
33. M. Ishida, S. W. Park, D. Hwang, Y. B. Koo, J. L. Sessler, D. Y. Kim, D. Kim, Donor-Substituted β-Functionalized Porphyrin Dyes on
Hierarchically Structured Mesoporous TiO2 Spheres. Highly Efficient Dye-Sensitized Solar Cells, J. Phys. Chem. C 115(2011) 1934319354.
34. M. S. Kang, S. H. Kang, S. G. Kim, I. Taek-Choi, J. H. Ryu, M. J. Ju, D. Cho, J. Y. Leeb, H. K. Kim, Novel D–π–A Structured Zn(II)Porphyrin Dyes Containing a Bis(3,3-dimethylfluorenyl)amine Moiety for Dye-Sensitized Solar Cells, Chem. Commun. 48(2012) 93499351.
35. H. Verma, N. Ghosh, Exciton Energy and Charge Transfer in Porphyrin Aggregate/Semiconductor (TiO2) Composites, J. Phys. Chem.
Lett. 3(2012) 1877-1884.
36. C. P. Hsieh, H. P. Lu, C. L. Chiu, C. W. Lee, S. H. Chuang, C. L. Mai, W. N. Yen, S. J. Hsu, E. W. G. Diau, C. Y. Yeh, Synthesis and
Characterization of Porphyrin Sensitizers with Various Electron-Donating Substituents for Highly Efficient Dye-Sensitized Solar Cells,
J. Mater. Chem. 20(2010) 1127-1134.
37. H. P. Lu, C. L. Mai, C. Y. Tsia, S. J. Hsu, C. P. Hsieh, C. L. Chiu, C. Y. Yeh, E. W. G. Diau, Design and Characterization of Highly
Efficient Porphyrin Sensitizers for Green See-through Dye-Sensitized Solar Cells, Phys. Chem. Chem. Phys. 11(2009) 10270-10274.
38. C. Y. Lin, Y. C. Wang, S. J. Hsu, C.-F. Lo, E. W. G. Diau, Preparation and Spectral, Electrochemical, and Photovoltaic Properties of
Acene-Modified Zinc Porphyrins, J. Phys. Chem. C 114(2010) 687-693.
39. C. H. Wu, T. Y. Pan, S. H. Hong, C. L. Wang, H. H. Kuo, Y. Y. Chu, E. W. G. Diau, C. Y. Lin, A Fluorene-modified Porphyrin for
Efficient Dye-Sensitized Solar Cells, Chem. Commun. 48(2012) 4329-4331.
40. C. L. Wang, Y. C. Chang, C.M. Lan, C. F. Lo, E. W. G. Diau, C. Y. Lin, Enhanced Light Harvesting with π-Conjugated Cyclic Aromatic
Hydrocarbons for Porphyrin-Sensitized Solar Cells, Energy. Environ. Sci. 4(2011) 1788-1795.
41. C. Jiao, N. Zu, K.-W. Huang, P. Wang, J. Wu, Perylene Anhydride Fused Porphyrins as Near-Infrared Sensitizers for Dye-Sensitized
Solar Cells, Org. Lett. 13(2011) 3652-3655.
42. J. M. Ball, N. K. S. Davis, J. D. Wilkinson, J. Kirkpatrick, J. Teuscher, R. Gunning, H. L. Anderson, H. J. Snaith, A
Panchromatic Anthracene-Fused Porphyrin Sensitizer for Dye-Sensitized Solar Cells, RSC Adv. 2(2012) 6846-6853.
43. A. Yella, H.-W. Lee, H. N. Tsao, C. Yi, A. K. Chandiran, M. K. Nazeeruddin, E. W.-G. Diau, C.-Y. Yeh, S. M. Zakeeruddin, M. Grätzel,
Porphyrin-Sensitized Solar Cells with Cobalt (II/III)-based Redox Electrolyte exceed 12 Percent Efficiency, Science 334(2011) 629-634.
44. J. Luo, M. Xu, R. Li, K. W. Huang, C. Jiang, Q. Qi, W. Zeng, J. Zhang, C. Chi, P. Wang, J. Wu, N-Annulated Perylene as An Efficient
Electron Donor for Porphyrin-Based Dyes: Enhanced Light-Harvesting Ability and High-Efficiency Co(II/III)-Based Dye-Sensitized
Solar Cells, J. Am. Chem. Soc. 136(2014) 265-272.
45. M. S. Kang, I. T. Choi, Y. W. Kim, B. S. You, S. H. Kang, J. Y. Hong, M. J. Ju, H. K. Kim, Novel D–π–A Structured Zn(II)–
Porphyrin Dyes with Bulky Fluorenyl Substituted Electron Donor Moieties for Dye-Sensitized Solar Cells, J. Mater. Chem. A 1(2013)
9848-9852.
46. Y. Wang, B. Chen, W. Wu, X. Li, W. Zhu, H. Tian, Y. Xie, Efficient Solar Cells Sensitized by Porphyrins with an Extended Conjugation
Framework and a Carbazole Donor: From Molecular Design to Cosensitization, Angew. Chem., Int. Ed. 53(2014) 10779–10783.
47. C. L. Wang, J. W. Shiu, Y. N. Hsiao, P. S. Chao, E. W. G. Diau, C.-Y. Lin, Co-Sensitization of Zinc and Free-Base Porphyrins with an
Organic Dye for Efficient Dye-Sensitized Solar Cells, J. Phys. Chem. C 118(2014) 27801−27807.
48. X. Sun, Y. Wang, X. Li, H. Ågren, W. Zhu, H. Tiana, Y. Xie, Cosensitizers for Simultaneous Filling up of Both Absorption Valleys of
Porphyrins: a Novel Approach for Developing Efficient Panchromatic Dye-Sensitized Solar Cells, Chem. Commun. 50(2014) 1560915612.
49. J. Liu, B. Liu, Y. Tang, W. Zhang, W. Wu, Y. Xiea, W. -H. Zhu, Highly efficient cosensitization of D–A–π–A Benzotriazole Organic
Dyes with Porphyrin for Panchromatic Dye-Sensitized Solar Cells, J. Mater. Chem. C 3(2015) 11144-11150.
50. Y. Xie, Y. Tang, W. Wu, Y. Wang, J. Liu, X. Li, H. Tian, W. H. Zhu, Porphyrin Cosensitization for a Photovoltaic Efficiency of 11.5%:
A Record for Non-Ruthenium Solar Cells Based on Iodine Electrolyte, J. Am. Chem. Soc. 137(2015) 14055-14058.
12
ACCEPTED MANUSCRIPT
AC
C
EP
TE
D
M
AN
U
SC
RI
PT
51. S. H. Kang, M. J. Jeong, Y. K. Eom, I. T. Choi, S. M. Kwon, Y. Yoo, J. Kim, J. Kwon, J. H. Park, H. K. Kim, Porphyrin Sensitizers with
Donor Structural Engineering for Superior Performance Dye-Sensitized Solar Cells and Tandem Solar Cells for Water Splitting
Applications, Adv. Energy Mater. (2017) 1602117.
52. B. K. Tripuramallu, R. Palakuri, H. M. Titi, I. Goldberg, Scalable Synthesis and Supramolecular Assembly of trans-A2B2 Porphyrins
with Pendant Carboxylic Functional Groups, Chem. Select 2(2017) 885-893.
53. S. Das, H. R. Bhat, N. Balsukuri, P. C. Jha, Y. Hisamune, M. Ishida, H. Furuta, S. Mori, I. Gupta, Donor–Acceptor type A2B2
Porphyrins: Synthesis, Eergy Transfer, Computational and Electrochemical Studies, Inorg. Chem. Front. 4(2017) 618-638.
54. K. Sudha, S. Sundharamurthi, S. Karthikaikumar, K. Abinaya, P. Kalimuthu, Switching of Förster to Dexter Mechanism of Short-Range
Energy Transfer in meso-Anthrylporphyrin, J. Phys. Chem. C 121(2017) 5941-5948.
55. S. Caprasecca, B. Mennucci, Excitation Energy Transfer in Donor-Bridge-Acceptor Systems: A Combined QuantumMechanical/Classical Analysis of the Role of the Bridge and the Solvent, J. Phys. Chem. A 118(2014) 6484-6491.
56. Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.; Robb, M. A.; Cheeseman, J. R.; Scalmani, G.; Barone, V.; Mennucci, B.;
Petersson, G. A., Nakatsuji, H., Caricato, M., Li, X.; Hratchian, H. P.; Izmaylov, A. F.; Bloino, J.; Zheng, G.; Sonnenberg, J. L.; Hada,
M.; Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa, J.; Ishida, M.; Nakajima, T.; Honda, Y.; Kitao, O.; Nakai, H., Vreven, T.; ,
Montgomery, J. A. Jr.; Peralta, J. E.; Ogliaro, F.; Bearpark, M.; Heyd, J. J.; Brothers, E.; Kudin, K. N.; Staroverov, V. N.; Kobayashi, R.;
Normand, J.; Raghavachari, K.; Rendell, A.; Burant, J. C.; Iyengar, S. S.; Tomasi, J.; Cossi, M.; Rega, N.; Millam, J. M.; Klene, M.;
Knox, J. E.; Cross, J. B.; Bakken, V.; Adamo, C.; Jaramillo, J.; Gomperts, R.; Stratmann, R. E.; Yazyev, O.; Austin, A. J.; Cammi, R.;
Pomelli, C.; Ochterski, J. W.; Martin, R. L.; Morokuma, K.; Zakrzewski, V. G.; Voth, G. A.; Salvador, P.; Dannenberg, J. J.; Dapprich,
S.; Daniels, A. D.; Farkas, Ö.; Foresman, J. B., Ortiz, J. V.; Cioslowski, J.; Fox, D. J. Gaussian 09, Revision B.01, Gaussian, Inc.,
Wallingford CT, 2010.
57. W. Wu, J. Yang, J. Hua, J. Tang, L. Zhang, Y. Long, H. Tian, Efficient and Stable Dye- Sensitized Solar Cells Based on Phenothiazine
Sensitizers with Thiophene Units, J. Mater. Chem. 20(2010) 1772-1779.
58. X. Qian, L. Lu, Y.-Z. Zhu, H.-H. Gaoa, J.-Y. Zheng, Phenothiazine-Functionalized Push–Pull Zn Porphyrin Photosensitizers for Efficient
Dye-Sensitized Solar Cells, RSC Adv. 6(2016) 9057-9065.
59. Q. Qi, R. Li, J. Luo, B. Zheng, K.-W. Huang, P. Wang, J. Wu, Push-pull type Porphyrin based Sensitizers: The Effect of Donor Structure
on the Light-Harvesting Ability and Photovoltaic Performance, Dyes Pig. 122(2015) 199-205.
60. Y. Tang, Y. Wang, X. Li, H. Ågren, W.-H. Zhu; Y. Xie, Porphyrins Containing a Triphenylamine Donor and up to Eight Alkoxy Chains
for Dye-Sensitized Solar Cells: A High Efficiency of 10.9%. ACS Appl. Mater. Interfaces 7(2015) 27976-27985.
61. A. S. Hart, B. K. C. Chandra, K. S. Navaneetha, A. K. Paul, D. Francis, Phenothiazine-Sensitized Organic Solar Cells: Effect of Dye
Anchor Group Positioning on the Cell Performance, ACS Appl. Mater. Interfaces 4(2012) 5813-5820.
62. G. Marotta, M. A. Reddy, S. P. Singh, A. Islam, L. Han, F. D. Angelis, M. Pastore, M. Chandrasekharam, Novel CarbazolePhenothiazine Dyads for Dye-Sensitized Solar Cells: A Combined Experimental and Theoretical Study, ACS Appl. Mater.
Interfaces 5(2013) 9635-9647.
63. G. Magnano, D. Marinotto, M. P. Cipolla, V. Trifiletti, A. Listorti, P. R. Mussini, G. Di Carlo, F. Tessore, M. Manca,
A. Orbelli Biroli, M. Pizzotti, Influence of Alkoxy Chain Envelopes on the Interfacial Photoinduced Processes in Tetraarylporphyrin
Sensitized Solar Cells, Phys. Chem. Chem. Phys. 18(2016) 9577-9585.
64. O. A. Biroli, F. Tessore, V. Vece, G. Di Carlo, P. R. Mussini, V. Trifiletti, L. De Marco, R. Giannuzzi, M. Manca, M. Pizzotti, Highly
Improved Performance of ZnII Tetraarylporphyrinates in DSSCs by the Presence of Octyloxy Chains in the Aryl Rings, J. Mater. Chem.
A 3(2015) 2954-2959.
65. B. Liu, W. H. Zhu, Y. Q. Wang, W. J. Wu, X. Li, B. Q. Chen, Y. T. Long, Y. S. Xie, Modulation of Energy Levels by Donor Groups: an
Effective Approach for Optimizing the Efficiency of Zinc-Porphyrin Based Solar Cells, J. Mater. Chem. 22(2012) 7434-7444.
66. C. H. Wu, M. C. Chen, P. C. Su, H. H. Kuo, C. L. Wang, C. Y. Lu, C. H. Tsai, C. C. Wu, C. Y. Lin, Porphyrins for Efficient
DyeSensitized Solar Cells Covering the Near-IR Region, J. Mater. Chem. A 2(2014) 991-999.
67. C. L. Wang, J. Y. Hu, C. H. Wu, H. H. Kuo, Y. C. Chang, Z. J. Lan, H. P. Wu, E. W. G. Diau, C. Y. Lin, Highly Efficient
Porphyrin-Sensitized Solar Cells with Enhanced Light Harvesting Ability Beyond 800 nm and Efficiency Exceeding 10%, Energy
Environ. Sci. 7(2014) 1392-1396.
68. Wang Y., L. Xu, X. Wei, X. Li, H. Agren, W. Wu, 2-Diphenylaminothiophene as the Donor of Porphyrin Sensitizers for Dye-Sensitized
Solar Cells, New J. Chem. 38(2014) 3227-35.
69. T. Ripolles-Sanchis, B. C. Guo, H. P. Wu, T. Y. Pan, H. W. Lee, S. R. Raga, Design and Characterization of Alkoxy-wrapped Push-Pull
Porphyrins for Dye-Sensitized Solar Cells, Chem. Commun. 48(2012) 4368-70.
70. J. Pan, H. Song, C. Lian, H. Liu, Y. Xie, Cocktail Co-sensitization of Porphyrin Dyes with Additional Donors and Acceptors for
Developing Efficient Dye-Sensitized Solar Cells, Dyes Pig. 140(2017) 36-46.
71. N. V. Krishna, J. V. S. Krishna, S. P. Singh, L. Giribabu, A. Islam, I. Bedja, Bulky Nature Phenanthroimidazole-Based Porphyrin
Sensitizers for Dye-Sensitized Solar Cell Applications, J. Phys. Chem. C 121(2017) 25691-25704.
13
ACCEPTED MANUSCRIPT
AC
C
EP
TE
D
M
AN
U
SC
RI
PT
72. S. Fan, X. Lu, H. Sun, G. Zhou, Y. J. Chang, Z. S. Wang, Effect of the Co-sensitization Sequence on the Performance of Dye-Sensitized
Solar Cells with Porphyrin and Organic Dyes, Phys. Chem. Chem. Phys. 18(2016) 932-938.
73. J. W. Shiu, Y. C. Chang, C. Y. Chan, H. P. Wu, H. Y. Hsu, C. L. Wang, C. Y. Lin, E. W. G. Diau, Panchromatic Co-sensitization of
Porphyrin-Sensitized Solar Cells to Harvest Near-Infrared Light beyond 900 nm, J. Mater. Chem. A 3(2015) 1417-1420.
74. K. Prakash, S. Manchanda, V. Sudhakar, N. Sharma, M. Sankar, K. Krishnamoorthy, Facile Synthesis of β-Functionalized ‘Push-Pull’
Zn(II) Porphyrin for DSSC Application, Dyes Pig. 147(2017) 56-66.
75. M. K. Panda, G. D. Sharma, K. R. J. Thomas, A. G. Coutsolelos, A New Family of A2B2 type Porphyrin Derivatives: Synthesis,
Physicochemical Characterization and Their Application in Dye-Sensitized Solar Cells, J. Mater. Chem. 22(2012) 8092-8102.
76. R. B. Ambre, S. B. Mane, G. F. Chang, C. H. Hung, Effects of Number and Position of Meta and Para Carboxyphenyl Groups of Zinc
Porphyrins in Dye-Sensitized Solar Cells: Structure-Performance Relationship, ACS Appl. Mater. Interfaces 7(2015) 1879-1891.
77. K. K. Pasunooti, J. L. Song, H. Chai, P. Amaladass, W. Q. Deng, X. W. Liu, Synthesis, Characterization and Application of trans-D–B–
A-Porphyrin based Dyes in Dye-Sensitized Solar Cells, J. Photochem. Photobio. A: Chem. 218(2011) 219-225.
78. M. Pastore, F. De Angelis, Computational Modelling of TiO2 Surfaces Sensitized by Organic Dyes with Different Anchoring Groups:
Adsorption Modes, Electronic Structure and Implication for Electron Iinjection/Recombination, Phys. Chem. Chem. Phys. 14(2012) 920928.
79. Y. C. Chang, H. P. Wu, N. M. Reddy, H. W. Lee, H. P. Lu, C. Y. Yeh, E. W. G. Diau, The Influence of Electron Injection and
Charge Recombination Kinetics on the Performance of PorphyrinSensitized Solar Cells: Effects of the 4-Tert-butylpyridine Additive,
Phys. Chem. Chem. Phys. 15(2013) 4651-4655.
80. T. Wei, X. Sun, X. Li, H. Ågren, Y. Xie, Systematic Investigations on the Roles of the Electron Acceptor and Neighboring Ethynylene
Moiety in Porphyrins for Dye-Sensitized Solar Cells, ACS Appl. Mater. Interfaces 7(2015) 21956-2196.
81. W. Li, Z. Liu, H. Wu, Y. B. Cheng, Z. Zhao, H. He, Thiophene-Functionalized Porphyrins: Synthesis, Photophysical Properties, and
Photovoltaic Performance in Dye-Sensitized Solar Cells, J. Phys. Chem. C 119(2015) 5265-5273.
82. L. Han, A. Islam, H. Chen, C. Malapaka, B. Chiranjeevi, S. Zhang, X. Yang, M. Yanagida, High-Efficiency Dye-Sensitized Solar Cell
with a Novel Co-adsorbent, Energy Environ. Sci. 5(2012) 6057-6060.
83. Y. B. Shi, M. Liang, L. Wang, H. Y. Han, L. S. You, Z. Sun, S. Xue, New Ruthenium Sensitizers Featuring Bulky Ancil-lary Ligands
Combined with a Dual Functioned Coadsorbent for High Efficiency Dye-Sensitized Solar Cells, ACS Appl. Mater. Interfaces 5(2013)
144-153.
84. E. Kozma, I. Concina, A. Braga, L. Borgese, L. E. Depero, A. Vomiero, G. Sberveglieri, M. Catellani, Metal-Free Organic Sensitizers
with a Sterically Hindered Thiophene Unit for Efficient Dye-Sensitized Solar Cells, J. Mater. Chem. 21(2011) 13785-13788.
14
ACCEPTED MANUSCRIPT
Electronic Supplementary Information
Trans-A2B2 Zn(II) Porphyrin Dyes with Various Donor Groups and their Co-sensitization
for Highly Efficient Dye Sensitized Solar Cells
Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee – 247667, India
b
Polymers and Advanced Materials Laboratory, CSIR-NCL, Pune-411008, India
Table of content
Page No.
Experimental Section
16-20
1
Figure S1 H NMR spectrum of KP-H2-PYR-COOMe in CDCl3.
1
Figure S2 H NMR spectrum of KP-H2-CBZ-COOMe in CDCl3.
Figure S3 1H NMR spectrum of KP-H2-PTZ-COOMe in CDCl3.
1
M
AN
U
Figure S4 H NMR spectrum of KP-H2-BTP-COOMe in CDCl3.
SC
a
RI
PT
Kamal Prakash,a Vediappan Sudhakar,b Kothandam Krishnamoorthy*b and Muniappan
Sankar*a
1
Figure S5 H NMR spectrum of KP-H2-PYR-COOH in CDCl3.
1
Figure S6 H NMR spectrum of KP-H2-CBZ-COOH in CDCl3.
1
20
21
21
22
22
23
23
Figure S8 MALDI-TOF-MASS spectrum of KP-H2-PYR-COOMe.
24
Figure S9 MALDI-TOF-MASS spectrum of KP-H2-CBZ-COOMe.
24
Figure S10 MALDI-TOF-MASS spectrum of KP-H2-PTZ-COOMe.
25
Figure S11 MALDI-TOF-MASS spectrum of KP-H2-BTP-COOMe.
25
Figure S12 MALDI-TOF-MASS spectrum of KP-H2-PYR-COOH.
26
Figure S13 MALDI-TOF-MASS spectrum of KP-H2-CBZ-COOH.
26
Figure S14 MALDI-TOF-MASS spectrum of KP-H2-PTZ-COOH.
27
Figure S15 MALDI-TOF-MASS spectrum of KP-H2-BTP-COOH.
27
TE
D
Figure S7 H NMR spectrum of KP-H2-PTZ-COOH in CDCl3.
28
28
Figure S18 MALDI-TOF-MASS spectrum of KP-Zn-PTZ.
29
Figure S19 MALDI-TOF-MASS spectrum of KP-Zn-BTP.
29
EP
Figure S16 MALDI-TOF-MASS spectrum of KP-Zn-PYR.
Figure S17 MALDI-TOF-MASS spectrum of KP-Zn-CBZ.
30
30
Fig. S22 TD-DFT Simulated absorption spectra of KP-Zn-PTZ.
31
Fig. S23 TD-DFT Simulated absorption spectra of KP-Zn-BTP.
31
Fig. S24 Plots of interfacial charge resistanec (Rct) versus bias voltage of DSSCs based on (a) Zn(II)
33
AC
C
Fig. S20 TD-DFT Simulated absorption spectra of KP-Zn-PYR.
Fig. S21 TD-DFT Simulated absorption spectra of KP-Zn-CBZ.
porphyrin dyes (KP-Zn-BTP to KP-Zn-PTZ) and (b) N719 co-sensitized Zn(II)porphyrin dyes (KP-ZnBTP/N719 to KP-Zn-PTZ/N719).
Fig. S25 Plots of chemical capitance (Cµ) versus bias voltage of DSSCs based on (a) Zn(II) porphyrin dyes
(KP-Zn-BTP to KP-Zn-PTZ) and (b) N719 co-sensitized Zn(II)porphyrin dyes (KP-Zn-BTP/N719 to KPZn-PTZ/N719).
15
33
ACCEPTED MANUSCRIPT
Table S1. TD-DFT calculated excited electronic transition and corresponding oscillator strength for selected
32
singlet excited states of trans-A2B2 Zn(II) porphyrin dyes.
RI
PT
Experimental Section
Material
Methyl4-formylbenzoate was purchased from Sigma Aldrich, india and used as received. Carbazole, Phenothiazine, 1pyrenecarboxyaldehyde and 2,2’-bisthiophene-5-carboxyaldehyde were purchased from Alfa Acer, India. 10-ethyl-10H-
SC
phenothiazine-3-carbaldehyde and 9-ethyl-9H-carbazole-3-carbaldehyde were synthesized according to literature methods.
Potassium hydroxide (KOH) and Zn(OAc)2 2H2O were purchased from HiMedia, India, and used without further
purification. All solvents employed in this work were analytical grade, carefully dried and freshly distilled before use. Silica
M
AN
U
gel (Rankem laboratory, 100-200 mesh, India) column chromatography was employed to purify the compounds. TBAPF6
was received from Sigma Aldrich and recrystallized with C2H5OH before use. Dry THF was used for Cyclic voltammetry
studies.
Instrumentation and method
UV-visible spectra of trans-A2B2 porphyrin dyes were determined on Agilent Cary 100 spectrophotometer using in dry
dichloromethane and fluorescence spectra were recorded a Hitachi F-4600 spectrofluorometer using a pair of quartz cells of
TE
D
3.5 mL volume and 10 mm path length. 1H NMR spectra were recorded on JEOL ECX 400 MHz spectrometer using CDCl3
and DMSO-d6 as solvent. Mass spectra were recorded using a Bruker Ultraflextreme-TN MALDI-TOF-MS spectrometer
using HABA (2-(4՛-hydroxybenzeneazo)benzoic acid) as matrix. Fluorescence lifetime measurements were carried out on
“Horibe Jobin Yvon “Fluorocube Fluorescence lifetime system” equipped with NanoLEDs and LDs as the excitation source
and automated polarisation accessory. Electrochemical measurements were carried out using CH instrument (CH 620E). A
EP
three electrode assembly was used consisted of a platinum working electrode, Ag/AgCl as a reference electrode and a Ptwire as a counter electrode. The concentration of all compounds was maintained at 1 mM. All measurements were
performed in triple distilled CH2Cl2 containing 0.1 M TBAPF6 as supporting electrolyte, which was degassed by argon gas
AC
C
purging. ElementarVario EL II instrument was used to carry out the elemental analysis. Fluorescence quantum yield were
determined by the comparative method, using the following equation :
Std 2
.n
Ф = (ФF)std . F.A
FStd.A.(nStd)2
Where (ФF)std is standard quantum yield for Zn tetraphenylporphyrin (ZnTPP), F and FStd are the integrated areas under the
curves for samples and standard, A and AStd are the absorbance value at the excitation wavelength, and n and nStd are the
refractive indices of the solvent used.
16
ACCEPTED MANUSCRIPT
Fabrication of Dye sensitized solar cells
In this work, fabricated photoanode was prepared using TiO2 paste and Pt sheets worked as a counter electrode. In addition,
Fluorine-doped SnO2 glass (TEC-15, 2.2 mm thickness, Solaronix) was used for transparent conducting electrodes. Firstly,
The FTO plate was ultrasonically cleaned using a detergent solution followed by the distilled water, acetone and ethanol for
RI
PT
35 minutes successively. Then, The FTO glass plates were dipped into a 40 mM aqueous TiCl4 solution at 70 °C for 30 min
and again washed with water followed by ethanol. Now FTO plates were sintered 500 °C for 30 min. After that, 8 µm thick
film of mesoporous TiO2 paste and dried at 85 °C for 40 min. The TiO2 electrodes were sintered under the air flow at 325
°C for 5 min, at 375 °C for 5 min, at 450 °C for 15 min, and 500 °C for 15 min successively. After cooled at room
temperature, the 4 µm thick scattering layer of 400-nm sized light anatase particles was coated over the mesoporous TiO2
particles, and it was sintered under air flow at 325 °C for 5 min, at 375 °C for 5 min, at 450 °C for 15 min, and 500 °C for
SC
15 min. After completing this process, the TiO2 film was cooled down at room temperature and treated with 50 mM TiCl4
solution at 70 °C for 25 min. , rinsed with ethanol and again heated at 500 °C for 30 min. After cooled at 80 °C, the TiO2
electrodes were dipped in premade dye solution (0.2 mM porphyrin dyes and 1 mM CDCA in DMF/DCM solution (v/v:
M
AN
U
1/4)) for 12h. After that, Phtoanode was washed with ethanol to remove the unanchored dye and dried by air flow. Finally,
photoanodes and Pt counter electrode were accumulated together in sandwith type shape and the space was filled with
electrolyte (AN-50, Solarnix, Switzerland) solution. For the co-sensitized photoanode preparation, photoanode first dipped
into dye solution for 6h, dried to remove solvents, again dipped into N719 dye solution (0.3 mM N719 dyes in EtOH
solution) for 14h. The active area of TiO2 film was 0.235 cm2.
Synthetic Procedures for Porphyrinic Dyes
TE
D
Synthesis of 5-(4-Methoxycarboxyphenyl)dipyrromethane:
5-(4-Methoxycarboxyphenyl)dipyrromethane was prepared using the literature procedure.28 300 mL of 0.18 M aqueous HCl
was taken in 500 ml RB flask and purged with N2 for 15 minutes. 5g of methyl 4-formylbenzoate (0.0303 mol) was added
to this followed by the 7 ml of pyrrole (0.101mol). then, this reaction mixture was again purged for 5 minutes and stirred in
dark for overnight at room at room temperature. After completion, reaction mixture was extracted with CHCl3, washed with
water and dried over anhydrous sodium sulphate. The product was purified by flesh column chromatography on silica-gel
EP
using 20% hexane-ethyl acetate mixture as eluent. The yield of the desired product was found to be 4.0 g, 0.0143mol (47%
yield).1H NMR (500 MHz, CDCl3):δ (ppm) 8.05-7.90 (m, 4H, -NH proton and phenyl H), 7.28 (d, 2H, phenyl H), 6.75-6.65
(m, 2H, pyrrole H), 6.18-6.12 (m, 2H, β-pyrrole-H), 5.92-5.87 (m, 2H, pyrrole H), 5.54 (s, 1H, meso-CH), 3.90 (s, 3H, -
AC
C
COOCH3 proton).
Synthesis of trans-A2B2 Diester porphyrins:
5-(4-Methoxycarboxyphenyl)dipyrromethane (1 mmol) was taken dissolved into 240ml dichloromethane in 500ml RB flask
and the corresponding aromatic aldehyde (1 mmol) was added to this. The reaction mixture was purged with N2 gas for 30
minutes and then trifluoroacetic acid (0.150 ml) was added. The reaction mixture was stirred in dark for 3 hours. DDQ (1
mmol) was added to the reaction mixture and allowed to stirred for 1 hour more. After completion, triethylamine (TEA)
was added to neutralize the reaction mixture. The solvent was rotary evaporated to reduce. Silica gel column
chromatography was to performed to purify the compound using 1:1 hexane/chloroform mixture. The desired product Trans
A2B2 diester porphyrin was obtained as second fraction which was further recrystallized from CHCl3/CH3OH mixture. The
yield was found to be 7-10%.
17
ACCEPTED MANUSCRIPT
5,15-Bis(4′-Carbomethoxyphenyl)-10,20-bis(1’-pyrenyl)porphyrin (KP-H2-PYR-COOMe): 0.051 g, 0.052 mmol
(10.4% yield). UV-Vis. (λmax in nm): 423 (5.09), 516 (3.96), 549 (3.62), 593 (3.49), 653 (3.34). 1H NMR (400 MHz,
CDCl3): δ (ppm) 1H NMR (400 MHz, CDCl3): δ (ppm) 8.85-8.80 (m, 2H, β-pyrrole-H), 8.71 (d, 4H, β-pyrrole-H, 4.8Hz),
8.55-8.53 (m, 4H, β-pyrrole-H and pyrenyl-H), 8.41-8.29 (m, 16H, pyrenyl-H and meso-o & m-carbomethoxyphenyl-H),
8.13-8.06 (m, 4H, pyrenyl-H), 7.73 (d, 2H, pyrenyl-H, 12 Hz), 7.44 (t, 2H, pyrenyl-H, 8Hz), 4.05( s, 6H, -COOMe proton),
RI
PT
-2.38 (s, 2H, -NH proton). MALDI-TOF-MS (m/z): found 982.55 [M + 2H]+ , calcd 981.10 for C68H44N4O4. Elemental
analysis calcd. For C68H44N4O4: C, 83.18%; H, 4.25%; N, 5.63% and found: C, 83.25%; H, 4.52%; N, 5.71%.
5,15-Bis(4′-Carbomethoxyphenyl)-10,20-bis(9-ethyl-3-carbazole)porphyrin (KP-H2-CBZ-COOMe): 0.042 g, 0.043
mmol (8.6% yield). UV-Vis. (λmax in nm): 426 (5.41), 517 (4.19), 555 (4.04), 597(3.68), 653(3.79). 1H NMR (500 MHz,
CDCl3): δ (ppm) 1H NMR (400 MHz, CDCl3): δ (ppm) 8.94-8.90 (m, 6H, β-pyrrole-H and carbazole H), 8.80-8.79 (m, 4H,
β-pyrrole-H), 8.45-8.43 (m, 4H, meso-o-carbomethoxyphenyl-H), 8.35-8.33 (m, 6H, meso-m-carbomethoxyphenyl-H and
SC
carbazole-H), 8.20 (d, 2H, carbazole-H, 7.6 Hz), 7.76 (d, 2H, carbazole-H, 8.4 Hz), 7.62-7.57 (m, 4H, carbazole-H), 7.327.29 (m, 2H, carbazole-H), 4.65 (quartet, 4H, -CH2-H, 7.2 and 14.4 Hz), 4.10( s, 6H, -COOMe proton), 1.69(t, 6H, -CH3-H,
7.2 Hz), -2.60 (s, 2H, -NH proton). MALDI-TOF-MS (m/z): found 965.46 [M + H]+ , calcd. 964.37 for C64H48N6O4.
M
AN
U
Elemental analysis calcd. For C55H44N4O2S2: C, 79.65%; H, 5.01%; N, 8.71% and found: C, 79.12%; H, 5.67%; N, 8.03%;
S, 7.38.
5,15-Bis(4′-Carbomethoxyphenyl)-10,20-bis(10-ethyl-3-phenothiazine)porphyrin (KP-H2-PTZ-COOMe): 0.037 g,
0.036 mmol (7.2% yield). UV-Vis. (λmax in nm): 417 (5.43), 518 (4.31), 558 (4.18), 593(3.88), 654(3.86). 1H NMR (500
MHz, CDCl3): δ (ppm) 1H NMR (400 MHz, CDCl3): δ (ppm) 8.96-8.94 (m, 4H, β-pyrrole-H), 8.78-8.75 (m, 4H, β-pyrroleH), 8.44 (d, 4H, meso-o-carbomethoxyphenyl-H, 8 Hz), 8.30 (d, 4H, meso-m-carbomethoxyphenyl-H, 7.6 Hz), 7.96-7.94
(m, 6H, phenothiazine-H), 7.08-6.94 (m, 8H, phenothiazine-H), 4.23 (s, 4H, -CH2-H), 4.11( s, 6H, -COOMe-H), 1.66 (t,
6H, -CH3-H, 6.4 Hz), -2.81 (s, 2H, -NH proton). MALDI-TOF-MS (m/z): found 1029.76 [M + 2H]+ , calcd 1028.32 for
H, 4.50%; N, 8.19; S, 6.77%.
TE
D
C64H48N6O4S2. Elemental analysis calcd. For C64H48N6O4S2: C, 74.69%; H, 4.70; N, 8.17; S, 6.23%. and found: C, 74.20%;
5,15-Bis(4′-Carbomethoxyphenyl)-10,20-bis(bisthiophene)porphyrin (KP-H2-BTP-COOMe): 0.037 g, 0.040 mmol
(8% yield). UV-Vis. (λmax in nm): 426 (3.72), 520 (3.56), 561 (3.51), 595(3.29), 658(3.27). 1H NMR (500 MHz, CDCl3): δ
(ppm) 1H NMR (400 MHz, CDCl3): δ (ppm) 9.22-9.19 (m, 4H, β-pyrrole-H), 8.80-8.76 (m, 4H, β-pyrrole-H), 8.48-8.42 (m,
EP
4H, meso-o-carbomethoxyphenyl-H), 8.31-8.26 (m, 4H, meso-m-carbomethoxyphenyl-H), 7.82-7.78 (m, 2H, bisthiopheneH), 7.59-7.57 (m, 2H, bisthiophene-H), 7.43-7.40 (m, 2H, bisthiophene-H), 7.36-7.33 (m, 2H, bisthiophene-H), 7.15-7.11
(m, 2H, bisthiophene-H), 4.10( s, 6H, -COOMe proton), -2.70 (s, 2H, -NH proton). MALDI-TOF-MS (m/z): found 909.50
AC
C
[M + 2H]+ , calcd 907.11 for C52H34N4O4S4. Elemental analysis calcd. For C52H34N4O4S4: C, 68.85%; H, 3.78%; N, 6.18; S,
14.14% and found: C, 68.28%; H, 3.79%; N, 6.08; S, 14.45%.
Synthesis of trans-A2B2 Diacid porphyrin:
Diester porphyrin (0.05 mmol) (1a-1e) was dissolved in 20ml of THF. Potassium hydroxide (5 mmol) in minimum amount
of water was added to the reaction mixture and refluxed at 90 °C for 24 hrs. After completion, solvent was evaporated under
vacuum. 15 ml of 4N HCl was added to crude reaction mixture to get green precipitate. Now, porphyrin product was
filtered, washed with excess of water and acetone and dried. The dried product was final product and directly used for
further synthesis. The yield of the product was found to be 80-90%.
5,15-Bis(4′-Carboxyphenyl)-10,20-bis(1’-pyrenyl)porphyrin (KP-H2-PYR-COOH): 86% yield. UV-Vis. (λmax in nm):
423 (4.98), 514 (3.83), 551 (3.50), 594 (3.25), 651 (3.57). 1H NMR (400 MHz, CDCl3): δ (ppm) 1H NMR (400 MHz,
18
ACCEPTED MANUSCRIPT
CDCl3): δ (ppm) 13.21 (s, 2H, -COOH-H), 8.88 (m, 2H, β-pyrrole-H,), 8.74-8.69 (m, 4H, β-pyrrole-H), 8.56-8.53 (m, 4H,
β-pyrrole-H and pyrenyl-H), 8.47-8.43 (m, 8H, pyrenyl-H and meso-o-carbomethoxyphenyl-H), 8.38-8.31 (m, 8H, pyrenylH and meso-m-carbomethoxyphenyl-H), 8.23 (d, 2H, pyrenyl-H, 7.2 Hz), 8.15 (t, 2H, pyrenyl-H, 7.6 Hz), 7.85 (d, 2H,
pyrenyl-H, 9.6Hz), 7.28-7.26 (m, 2H, pyrenyl-H), -2.47 (s, 2H, -NH proton). MALDI-TOF-MS (m/z): found 954.68 [M +
H]+ , calcd. 953.05 for C66H40N4O4. Elemental analysis calcd. For C66H40N4O4: C, 83.88%; H, 4.23%; N, 5.88%; and found:
RI
PT
C, 83.12%; H, 4.67%; N, 5.03%.
5,15-Bis(4′-Carboxyphenyl)-10,20-bis(9-ethyl-3-carbazole)porphyrin (KP-H2-CBZ-COOH): 90% yield. UV-Vis. (λmax
in nm): 425 (5.56), 518 (5.34), 558 (4.19), 595(3.86), 651(3.94). 1H NMR (400 MHz, CDCl3): δ (ppm) 1H NMR (400 MHz,
CDCl3): δ (ppm) 13.46 (s, 2H, -COOH-H), 9.51 (s, 1H, carbazole-H), 9.04 (d, 1H, β-pyrrole-H), 8.91-8.81 (m, 7H, βpyrrole-H), 8.69-8.58 (m, 6H, meso-o-carbomethoxyphenyl-H and carbazole-H), 8.59-8.32 (m, 8H, meso-mcarbomethoxyphenyl-H and carbazole-H), 8.03 (d, 1H, carbazole-H, 8.8 Hz), 7.92 (d, 1H, carbazole-H, 8.4 Hz), 7.80 (d,
SC
1H, carbazole-H, 8.4 Hz), 7.69 (t, 1H, carbazole-H, 7.2 Hz), 7.57 (t, 1H, carbazole-H, 8 Hz), 7.47 (t, 1H, carbazole-H, 6.8
Hz), 7.26 (t, 1H, carbazole-H, 7.2 Hz), 4.82-4.70 (m, 4H, -CH2-H), 1.62-1.55(t, 6H, -CH3-H), -2.76 (s, 2H, -NH proton).
MALDI-TOF-MS (m/z): found 937.58 [M + H]+ , calcd. 936.38 for C62H44N6O4. Elemental analysis calcd. For C62H44N6O4:
M
AN
U
C, 76.47%; H, 4.73%; N, 8.97% and found: C, 79.82%; H, 4.62%; N, 8.45%.
5,15-Bis(4′-Carbomethoxyphenyl)-10,20-bis(10-ethyl-3-phenothiazine)porphyrin (KP-H2-PTZ-COOH): 80% yield.
UV-Vis. (λmax in nm): 418 (5.34), 518 (4.31), 558 (4.21), 592(3.96), 652(3.86). 1H NMR (500 MHz, CDCl3): δ (ppm) 1H
NMR (400 MHz, CDCl3): δ (ppm) 13.30 (s, 2H, -COOH-H), 8.95-8.94 (m, 4H, β-pyrrole-H), 8.81-8.80 (m, 4H, β-pyrroleH), 8.38-8.31 (m, 8H, meso o- and m-carbomethoxyphenyl-H, 8 Hz), 8.02-7.98 (m, 4H, phenothiazine-H), 7.43 (d, 2H,
phenothiazine-H, 8.4 Hz), 7.31 (t, 2H, phenothiazine-H, 8.4 Hz), 7.22 (dd, 2H, phenothiazine-H, 8 Hz, 10 Hz), 7.03 (t, 2H,
phenothiazine-H, 7.6 Hz), 4.17 (quartet, 4H, -CH2-H, 6.4 and 13.2 Hz), 1.51 (t, 6H, -CH3-H, 7.2 Hz), -2.92 (s, 2H, -NH
proton). MALDI-TOF-MS (m/z): found 1002.63 [M + H]+ , calcd. 1001.18 for C62H44N6O4S2. Elemental analysis calcd. For
TE
D
C62H44N6O4S2: C, 74.38%; H, 4.43%; N, 8.39; S, 6.41% and found: C, 74.22%; H, 4.27%; N, 8.06; S, 6.40%.
5,15-Bis(4′-Carboxyphenyl)-10,20-bis(2’-bisthiophene)porphyrin (KP-H2-BTP-COOH): 83% yield. UV-Vis. (λmax in
nm): 426 (5.10), 520 (4.91), 560 (4.84), 596(3.54), 657(3.53). MALDI-TOF-MS (m/z): found 880.23 [M + H]+ , calcd
879.06 for C50H30N4O4S4. Elemental analysis calcd. For C50H30N4O4S4: C, 68.32; H, 3.44%; N, 6.37; S, 14.59% and found:
EP
C, 68.43%; H, 3.21%; N, 6.61%; S, 14.34.
Synthesis of trans-A2B2 Zn(II) diacid porphyrin dyes:
Free base diacid porphyrin (0.05 mmol) was taken in 100 mL RB flask and dissolved into 25 mL DMF. 10 equivalents of
AC
C
Zn(OAc)•2H2O (0.5 mmol) was added to the reaction mixture and heated for 1 hr. Then, reaction mixture was cooled to
room temperature, water as and the solvent was removed by under vaccum. Then it was cooled to room temperature, added
water to get precipitate porphyrin and filtered on G-4 crucible. The crude product was washed with water and acetone and
dried in oven for 6 hr at 85 °C. This dried product is final Zn(II) pophyrin dyes. the yield of Zn porphyrin dyes were found
to 85-96% yield. These porphyrin dyes have very solubility in CDCl3, DMSO-d6, CD3OD-d6 solvents. So, we characterized
the final product by UV-vis, MALDI-MASS spectra and CHN analysis.
5,15-Bis(4′-Carboxyphenyl)-10,20-bis(1’-pyrenyl) porphyrinato zinc(II) (KP-Zn-PYR): 85% yield. UV-Vis. (λmax in
nm): 430 (5.35), 555 (4.13). MALDI-TOF-MS (m/z): found 1015.58 [M + 2H]+ , calcd 1014.22 for C66H38N4O4Zn.
Elemental analysis calcd. For C66H38N4O4Zn: C, 76.75%; H, 5.25%; N, 6.63%; S, 7.59 and found: C, 76.12%; H, 5.67%; N,
6.03%; S, 7.38.
19
ACCEPTED MANUSCRIPT
5,15-Bis(4′-Carboxyphenyl)-10,20-bis(9-ethyl-3-carbazole) porphyrinato zinc(II) (KP-Zn-CBZ): 88% yield. UV-Vis.
(λmax in nm): 430 (5.52), 561 (4.22), 600 (3.98). MALDI-TOF-MS (m/z): found 999.20 [M + H]+ , calcd 998.26 for
C62H42N6O4Zn. Elemental analysis calcd. For C62H42N6O4Zn: C, 74.43%; H, 4.23%; N, 8.40% and found: C, 74.31%; H,
4.59%; N, 8.43.
5,15-Bis(4′-Carbomethoxyphenyl)-10,20-bis(10-ethyl-3-phenothiazine) porphyrinato zinc(KP-Zn-PTZ) (1b): 96%
RI
PT
yield. UV-Vis. (λmax in nm): 428 (5.71), 559 (3.59), 602(3.36). MALDI-TOF-MS (m/z): found 1063.41 [M + 2H]+ , calcd.
1062.20 for C62H42N6O4S2Zn. Elemental analysis calcd. For C62H42N6O4S2Zn: C, 69.95%; H, 3.98%; N, 7.89; S, 6.02% and
found: C, 69.81%; H, 3.73%; N, 7.56; S, 6.11%.
5,15-Bis(4′-Carboxyphenyl)-10,20-bis(2’-bisthiophene)porphyrinato zinc(II) (KP-Zn-BTP): 91% yield. UV-Vis. (λmax
in nm): 432 (5.21), 559 (4.19), 605 (3.53). MALDI-TOF-MS (m/z): found 941.07 [M + 2H]+ , calcd 940.03 for
C50H28N4O4S4Zn. Elemental analysis calcd. For C50H28N4O4S4Zn: C, 63.72%; H, 2.99%; N, 5.94%; S, 13.61 and found: C,
AC
C
EP
TE
D
M
AN
U
SC
63.70%; H, 2.90%; N, 5.72; S, 13.14%.
Figure S1. 1H NMR spectrum of KP-H2-PYR-COOMe in CDCl3.
20
M
AN
U
SC
RI
PT
ACCEPTED MANUSCRIPT
AC
C
EP
TE
D
Figure S2. 1H NMR spectrum of KP-H2-CBZ-COOMe in CDCl3.
Figure S3. 1H NMR spectrum of KP-H2-PTZ-COOMe in CDCl3.
21
M
AN
U
SC
RI
PT
ACCEPTED MANUSCRIPT
AC
C
EP
TE
D
Figure S4. 1H NMR spectrum of KP-H2-BTP-COOMe in CDCl3.
Figure S5. 1H NMR spectrum of KP-H2-PYR-COOH in DMSO-d6.
22
M
AN
U
SC
RI
PT
ACCEPTED MANUSCRIPT
AC
C
EP
TE
D
Figure S6. 1H NMR spectrum of KP-H2-CBZ-COOH in DMSO-d6.
Figure S7. 1H NMR spectrum of KP-H2-PTZ-COOH in DMSO-d6.
23
M
AN
U
SC
RI
PT
ACCEPTED MANUSCRIPT
AC
C
EP
TE
D
Figure S8. MALDI-TOF-MASS spectrum of KP-H2-PYR-COOMe.
Figure S9. MALDI-TOF-MASS spectrum of KP-H2-CBZ-COOMe.
24
M
AN
U
SC
RI
PT
ACCEPTED MANUSCRIPT
AC
C
EP
TE
D
Figure S10. MALDI-TOF-MASS spectrum of KP-H2-PTZ-COOMe.
Figure S11. MALDI-TOF-MASS spectrum of KP-H2-BTP-COOMe.
25
M
AN
U
SC
RI
PT
ACCEPTED MANUSCRIPT
AC
C
EP
TE
D
Figure S12. MALDI-TOF-MASS spectrum of KP-H2-PYR-COOH.
Figure S13. MALDI-TOF-MASS spectrum of KP-H2-CBZ-COOH.
26
M
AN
U
SC
RI
PT
ACCEPTED MANUSCRIPT
AC
C
EP
TE
D
Figure S14. MALDI-TOF-MASS spectrum of KP-H2-PTZ-COOH.
Figure S15. MALDI-TOF-MASS spectrum of KP-H2-BTP-COOH.
27
M
AN
U
SC
RI
PT
ACCEPTED MANUSCRIPT
AC
C
EP
TE
D
Figure S16. MALDI-TOF-MASS spectrum of KP-Zn-PYR.
Figure S17. MALDI-TOF-MASS spectrum of KP-Zn-CBZ.
28
M
AN
U
SC
RI
PT
ACCEPTED MANUSCRIPT
AC
C
EP
TE
D
Figure S18. MALDI-TOF-MASS spectrum of KP-Zn-PTZ.
Figure S19. MALDI-TOF-MASS spectrum of KP-Zn-BTP.
29
M
AN
U
SC
RI
PT
ACCEPTED MANUSCRIPT
AC
C
EP
TE
D
Fig. 20 TD-DFT Simulated absorption spectra of KP-Zn-PYR.
Fig. 21 TD-DFT Simulated absorption spectra of KP-Zn-CBZ.
30
M
AN
U
SC
RI
PT
ACCEPTED MANUSCRIPT
AC
C
EP
TE
D
Fig. 22 TD-DFT Simulated absorption spectra of KP-Zn-PTZ.
Fig. 23 TD-DFT Simulated absorption spectra of KP-Zn-BTP.
31
ACCEPTED MANUSCRIPT
Table S1. TD-DFT calculated excited electronic transition and corresponding oscillator strength for selected singlet excited
states of trans-A2B2Zn(II) porphyrin dyes.
Energy (eV)
fb
569
2.18
0.0537
S8
408
3.04
0.3703
S1
532
2.32
S8
400
3.10
S1
548
S7
408
KP-Zn-PYR
KP-Zn-CBZ
L+1
L
0.0447
0.0221
2.26
0.0756
3.04
0.4143
2.18
0.2394
H–6
L
H–3
L+1
H–2
L
H–2
L+3
H
L+3
H–3
L+1
H–1
L+1
H
L
H–4
L+1
H–3
L
H–1
L
H
L+1
H–1
L+1
H
L
H–6
L
H–3
L
H–1
L+1
H
L
H
L+2
H
L+3
H–1
L+1
H
L
S7
405
3.06
0.4054
H–4
L +1
H–3
L+1
H–1
L
H
L
H
L+5
a
Only main transition were shown. bOscillator strength. states. dH stand for HOMO and L stand for LUMO.
S1
AC
C
EP
KP-Zn-BTP
567
H–3
H
RI
PT
S1
MO composition
SC
KP-Zn-PTZ
Wavelength(nm)
M
AN
U
Excited
statea
TE
D
Zn(II) Por. dye
32
SC
RI
PT
ACCEPTED MANUSCRIPT
(a)
(b)
TE
D
M
AN
U
Figure 24. Plots of interfacial charge resistanec (Rct) versus bias voltage of DSSCs based on (a) Zn(II) porphyrin dyes (KP-ZnBTP to KP-Zn-PTZ) and (b) N719 co-sensitized Zn(II)porphyrin dyes (KP-Zn-BTP/N719 to KP-Zn-PTZ/N719).
EP
(a)
(b)
AC
C
Figure 25. Plots of chemical capitance (Cµ) versus bias voltage of DSSCs based on (a) Zn(II) porphyrin dyes (KP-Zn-BTP to KPZn-PTZ) and (b) N719 co-sensitized Zn(II)porphyrin dyes (KP-Zn-BTP/N719 to KP-Zn-PTZ/N719).
33
ACCEPTED MANUSCRIPT
Highlights
Synthesis of trans-A2B2 push-pull porphyrins by a facile three step synthetic route
The power conversion efficiency (PCE) linearly increases with electron donating ability
RI
PT
of meso-substituents
PCE for porphyrin dyes were in range of 1.7 to 5.5% which dramatically improves to 4.8
to 8.8% upon co-sensitization with N719 dye
AC
C
EP
TE
D
M
AN
U
SC
Electron transfer kinetics is in good correlation with observed PCE values
Документ
Категория
Без категории
Просмотров
0
Размер файла
1 766 Кб
Теги
dyepig, 2018, 029
1/--страниц
Пожаловаться на содержимое документа