Zinc-porphyrin dyes with different meso-Aryl substituents for dye-sensitized solar cells: Experimental and theoretical studies

Article abstract of DOI:10.1002/asia.201402766

A series of new zinc-porphyrin dyes that contain different meso substituents (phenyl, carbazole phenyl, and carbazole thiophenyl groups) and bithiophenyl cyanoacrylic acid as the π-conjugated anchoring moiety were designed, synthesized, and characterized

Full text of DOI:10.1002/asia.201402766

FULL PAPER
DOI: 10.1002/asia.201402766
Zinc–Porphyrin Dyes with Different meso-Aryl Substituents for Dye-
Sensitized Solar Cells: Experimental and Theoretical Studies
Kanokkorn Sirithip,[b] Narid Prachumrak,[a] Rattanawalee Rattanawan,[c]
Tinnagon Keawin,[c] Taweesak Sudyoadsuk,[c] Supawadee Namuangruk,[d]
iporn Jungsuttiwong,[c] and Vinich Promarak*[a, e]
Abstract: A series of new zinc–porphy-
rin dyes that contain different meso
substituents (phenyl, carbazole phenyl,
and carbazole thiophenyl groups) and
bithiophenyl cyanoacrylic acid as the
p-conjugated anchoring moiety were
designed, synthesized, and character-
ized as sensitizers for dye-sensitized
solar cells (DSSCs). The effects of
these meso substituents on the proper-
ties of the porphyrin dyes were theo-
retically and experimentally investigat-
ed. By meso substitution of the porphy-
rin ring with carbazole-aryl moieties,
the short-circuit current (Jsc) and open-
circuit voltage (Voc) of the DSSCs were
improved as was the power conversion
efficiency (h) owing to the influence of
both the suppression of dye aggrega-
tions and the enhanced charge separa-
tion and charge-injection efficiency of
the dye to TiO2 films. Among these
dyes, ZnPCPA made of the carbazole
phenyl meso substituents gave rise to
the highest
h
of 6.24% (Jsc =
Keywords: carbazoles
pigments porphyrinoids
substituent effects · zinc
·
dyes/
13.38 mAcmꢀ2, Voc =0.66 V, and fill
·
·
factor of 0.71).
Introduction
ficiency of DSSCs and to realize their structure–property re-
lationship. The use of organic dyes is primarily attractive
owing to their easy structural modifications, easy purifica-
tion, and low production cost.[5] To achieve high-perfor-
mance sensitizers, many studies have focused on improving
the following key properties of the dye molecule: (i) enhanc-
ing the light-harvesting efficiency, (ii) subduing the trend of
dye aggregations, and (iii) decreasing the charge recombina-
Dye-sensitized solar cells (DSSCs) have arisen as one of the
promising technologies for renewable energy on account of
their low cost, ease of assembly, and decent conversion effi-
ciency.[1] To date, a variety of dye sensitizers including tran-
sition-metal complexes,[2] porphyrins,[3] and metal-free or-
ganic molecules[4] have been investigated to improve the ef-
ꢀ
tion at the TiO2 and the triiodide ion (I3 ) interfaces.
Among these dyes, porphyrin has attracted a great deal of
attention because of its natural role in photosynthesis, its in-
tense absorption in the visible region, its high stability, and
the relative ease with which functional groups can be at-
tached to its basic structure.[6] Although incredible improve-
ment has been achieved recently for porphyrin-dye-based
DSSCs with a power conversion efficiency (h) reaching
a new record of 13% for SM315 dye,[7] this still lags behind
the performance of the challenging 16.7% efficiency of the
DSSC that used an organometal halide perovskite
(CH3NH3PbI3) as a dye sensitizer.[8]
[a] N. Prachumrak, Prof. V. Promarak
School of Chemistry and Center for Innovation in Chemistry
Institute of Science, Suranaree University of Technology
Muang District, Nakhon Ratchasima 30000 (Thailand)
E-mail: pvinich@sut.ac.th
[b] K. Sirithip
Department of Science and Technology
Faculty of Liberal Arts and Sciences
Roi-Et Rajabhat University
Roi-Et 45120 (Thailand)
[c] R. Rattanawan, T. Keawin, T. Sudyoadsuk, Sir i. Jungsuttiwong
Department of Chemistry, Faculty of Science
Ubon Ratchathani University
From the Goutermann orbital model of porphyrin
(Figure 1), in the ground state, the highest-occupied molecu-
lar orbitals (HOMOs) (a1u or a2u) have their orbital density
mostly on the porphyrin meso positions and the nitrogen
atoms with a small amount of electron density on the b-pyr-
rolic positions. In the excited state, the electrons go into the
lowest-unoccupied molecular orbitals (LUMOs) (eg), which
have their electron density on the b-pyrrolic and meso posi-
tions. This means that a porphyrin functionalized through
the meso positions would be expected to show a strong
effect on the properties of the macrocyclic core, especially
Ubon Ratchathani 34190 (Thailand)
[d] S. Namuangruk
National Nanotechnology Center
130 Thailand Science Park, Klong Luang
Pathumthani 12120 (Thailand)
[e] Prof. V. Promarak
PTT Group Frontier Research Center
PTT Public Company Limited
555 Vibhavadi Rangsit Road
Chatuchak, Bangkok 10900 (Thailand)
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/asia.201402766.
1
&
&
Chem. Asian J. 2014, 00, 0 – 0
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
These are not the final page numbers! ÞÞ

www.chemasianj.org
Vinich Promarak et al.
Figure 1. The Gouterman orbital models for the HOMO and LUMOs of
porphyrin.
with electron-donating arylamine or carbazole groups. Fur-
thermore, its inherent LUMO level is situated above the
conduction band of TiO2, and its HOMO level is below the
redox couple of the electrolyte solution required for charge
separation at the semiconductor–dye–electrolyte surface,
which makes it a good donor moiety.[9] So far, a large
number of porphyrins have been developed as sensitizers
for DSSCs such as carboxyphenyl metalloporphyrins (h=
0.2–3.6%);[10] thiophene-, olefin-, and acetylene-linked por-
phyrins (h=3.6–5.1%);[11] quinoxaline-fused porphyrins (h=
5.2–6.5%);[12] zinc–zinc porphyrin dimers (h=2.1–5.5%);[13]
bacteriochlorin (h=1.1–6.6%);[14] 2,4-pentadienoic acid b-
pyrrolic-functionalized porphyrins (h=3.03–7.47%);[15] phe-
nylethynyl-substituted
meso-(diarylamino)-substituted
porphyrins
porphyrins
(h=0.25–6.12%);[16]
(h=3.8–
Results and Discussion
Synthesis and Characterization
13%);[7,17] 4-ethynylstyryl b-pyrrolic-functionalized porphyr-
ins (h=4.3–7.1%);[18] and acene-modified porphyrins (h=
0.10–5.44%).[19] The performances of these porphyrins
varied depending on the chemical structure. Hence, a further
structural modification and improvement of the porphyrin-
based dye is still a challenge and needs to be carried out. In
this work, we therefore present the design, synthesis, charac-
terization, and properties of new functionalized porphyrin
dyes. We explore the possibility of improving the photovol-
taic performance of porphyrin-based DSSCs by tuning the
spectral and electrochemical characteristics of the porphyrin
dyes. The target zinc–porphyrins contain bithiophenyl cya-
noacrylic acid as the p-conjugated anchoring moiety and dif-
ferent meso substituents (phenyl, carbazole phenyl, and car-
bazole thiophenyl groups). Varying the type of the meso
substituents would provide a rational study of the effect of
the electron-donating properties, the bulkiness of the carba-
zole, and the charge-transfer properties of the phenyl and
thiophenyl linkages on the properties of the dyes. The use of
bithiophenyl cyanoacrylic acid would offer an effective elec-
tron-transfer bridge from the porphyrin core to the TiO2
film as observed in most of the high-efficiency organic
dyes.[4,20] The theoretical and experimental investigations of
the optical and physical properties and their applications as
sensitizers in DSSCs are also reported.
The synthetic route to the design of meso-substituted zinc–
porphyrin dyes ZnPPA, ZnPCPA, and ZnPCTA is presented
in Scheme 1. We began with the synthesis of aryl aldehydes
1,[21] 6, and 7. Aldehydes 6 and 7 were prepared by the Ull-
mann coupling of 3,6-di-tert-butylcarbazole with bromoaryl
aldehydes 5 and 2 catalyzed by PdACTHUNRGTNEGN(U OAc)2/PPh3/K2CO3 in o-
xylene under reflux conditions, respectively. The 5-(2-bro-
mothiophenyl)-10,15,20-triaryl-substituted zinc–porphyrins
3, 8, and 9 were then formed by the condensation of a 1:3
mixture of 5-bromothiophene-2-carbaldehyde (2) and the
relevant aldehydes 1, 6, or 7 with pyrrole in the presence of
trifluoroacetic acid (TFA) as the acid catalyst in CH2Cl2 fol-
lowed by oxidation with 2,3-dichloro-5,6-dicyano-1,4-benzo-
quinone (DDQ). Subsequently, the mixture of mono-, di-,
and tri-2-bromothiophenyl meso-substituted free-base por-
phyrins formed was metalated with ZnACHTUNTGRNEUNG(OAc)2·2H2O in
CH2Cl2/MeOH heated at reflux to facilitate the separation
of these mixed porphyrins by column chromatography. The
corresponding zinc–porphyrins 3, 8, and 9 were isolated in
5–8% yields. Coupling of 3, 8, and 9 with 5-formyl-2-thio-
pheneboronic acid catalyzed by [PdACHTUNGTRNEUNG(PPh3)4]/2m Na2CO3 in
THF afforded the relevant porphyrin aldehydes 4, 10, and
11 in 58–65%. Knoevenagel condensation of these alde-
hydes with cyanoacetic acid in the presence of piperidine in
MeOH under reflux conditions gave the target zinc–porphy-
rin dyes ZnPPA, ZnPCPA, and ZnPCTA as dark purple
solids in good yields of 76–84%. The chemical structures of
the porphyrin dyes were confirmed by 1H and 13C NMR
spectroscopy, IR, and MALDI-TOF mass spectrometry.
&
&
2
Chem. Asian J. 2014, 00, 0 – 0
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ÝÝ These are not the final page numbers!

www.chemasianj.org
Vinich Promarak et al.
Scheme 1. Synthesis of the zinc–porphyrin dyes. Reagents and conditions: (i) a) pyrrole, TFA, CH2Cl2, room temperature, then DDQ; b) Zn-
(OAc)2·2H2O, CH2Cl2/MeOH, heat; (ii) 5-formyl-2-thiopheneboronic acid, [Pd(PPh3)4], 2m Na2CO3 (aqueous), THF, heat; (iii) 3,6-di-tert-butylcarbazole,
Pd(OAc)2, PPh3, K2CO3, o-xylene, heat; and (iv) cyanoacetic acid, piperidine, MeOH, heat.
A
ACHTUNGTRENNUNG
ACHTUNGTRENNUNG
They exhibit good solubility in most organic solvents to
allow dye adsorption onto the TiO2 film, and thus fabrica-
tion of DSSCs could be performed.
UV/Vis absorption spectra of the dyes display characteristic
absorptions due to the zinc–porphyrin, which consist of two
sets of bands, namely, an intense Soret band that appears
between 400 and 450 nm in each case and two much weaker
Q bands (QACHTUNTRGENN(GU 1,0) and QACHTUTGNREN(NUNG 0,0)) that appear between 550 and
Optical, Electrochemical, and Thermal Properties
approximately 600 nm (Figure 2a). These characteristic ab-
sorption peaks arise on account of the configurational inter-
action of two porphyrin p–p* electronic transitions a1u(p)
and a2u(p)!eg(p*). The constructive interaction corresponds
to a strong allowed transition that gives rise to the Soret
Optical properties of the zinc–porphyrin dyes ZnPPA,
ZnPCPA, and ZnPCTA in a dilute solution of CH2Cl2 and
adsorbed onto TiO2 films are shown in Figure 2a,b, and the
relevant data are summarized in Table 1. In solutions, the
Figure 2. Plots of UV/Vis absorption spectra of the dyes a) in CH2Cl2 and b) adsorbed on TiO2 films. c) CV curves of the dyes measured in CH2Cl2 with
nBu4NPF6 as a supporting electrolyte at a scan rate of 50 mVsꢀ1
.
3
&
&
Chem. Asian J. 2014, 00, 0 – 0
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
These are not the final page numbers! ÞÞ

www.chemasianj.org
Vinich Promarak et al.
Table 1. Photophysical, physical, and electrochemical data of the zinc–porphyrin dyes.
sol
abs
sol
abs
[nm][b]
sol
em
l
(e)
l
l
T5d
E1/2 vs Ag/AgCl
Eogpt/Eegle/Ecgal
HOMO/LUMO
[eV][f]
Compound
[nm (105 mꢀ1 cmꢀ1)][a]
[nm][b] [8C][c]
[V][d]
[eV][e]
ZnPPA
ZnPCPA
ZnPCTA
418 (2.97), 546 (0.26), 590 (0.12)
298 (0.76), 430 (2.34), 553 (0.25), 597 (0.11) 429, 560, 605
297 (0.72), 438 (1.68), 561 (0.20), 609 (0.09) 434, 564, 611
424, 557, 600
607
614
626
510
521
518
ꢀ1.39, 0.77, 1.04
2.01/1.98/2.07
ꢀ5.13/ꢀ3.12
ꢀ5.22/ꢀ3.23
ꢀ5.19/ꢀ3.21
ꢀ1.38, 0.84, 1.10, 1.24 1.99/1.97/2.10
ꢀ1.39, 0.84, 1.30
1.98/1.95/2.10
[a] Measured in CH2Cl2. [b] Measured as dyes adsorbed on TiO2. [c] Obtained from TGA measured at 108Cminꢀ1 under N2. [d] Obtained from CV mea-
sured in CH2Cl2 at a scan rate of 50 mVsꢀ1 and nBu4NPF6 as electrolyte. [e] Calculated from Eogpt =1240/lonset; Egele =E ꢀE ; Ecgal calculated with the
re
ox
onset
onset
ox
TD-B3LYP/6-31G
(d,p) basis set in CH2Cl2 solvent by the C-PCM model. [f] Estimated from HOMO=ꢀ
(4.44+E ; LUMO=Eogpt+HOMO).
band, whereas the destructive interaction corresponds to
a weak disallowed transition that gives rise to the Q bands
at longer wavelength. In most porphyrins, in response to the
absorption of light, rapid population of the lowest-energy
excited singlet state occurs owing to fast nonradiative transi-
tions. In the cases of ZnPCPA and ZnPCTA, the additional
absorption peak due to the n–p* transition of carbazole pe-
ripheries is observed at approximately 298 nm. These dyes
exhibit high molar extinction coefficients (e=2.97–1.49ꢁ
105 mꢀ1 cmꢀ1) at the Soret bands. Upon replacement of the
phenyl meso substituents of ZnPPA with the carbazole-aryl
units, the Soret bands shifted toward longer wavelengths
from 418 to 430 and 438 nm for ZnPCPA and ZnPCTA, re-
spectively (Table 1). A similar pattern is observed for the Q
processes. The first oxidation wave is attributed to removal
of electrons from the zinc–porphyrin center to result in por-
phyrin radical cations. It is noteworthy that the first oxida-
tion potential of ZnPPA (E1/2 =0.77 V) occurs at a lower po-
tential than that of ZnPCPA and ZnPCTA (E1/2 =0.84 V),
thus supporting the notion that the porphyrin moiety is per-
turbed by the meso substitution with carbazole, as observed
in the optical properties. Multiple CV scans of ZnPPA,
ZnPCPA, and ZnPCTA display unchanged CV curves that
indicate electrochemically stable molecules. The HOMO
and LUMO energy levels of ZnPPA, ZnPCPA, and
ZnPCTA calculated from their oxidation onset potentials
ox
(E ) and optical energy gaps (Eogpt) are listed in Table 1.
onset
Their HOMO levels are ꢀ5.13 eV for ZnPPA, ꢀ5.22 eV for
ZnPCPA, and ꢀ5.19 eV for ZnPCTA, which are lower than
bands: the QACHTUNGTRENNUNG(0,0) bands redshift from 590 nm for ZnPPA to
ꢀ
597 and 609 nm for ZnPCPA and ZnPCTA, respectively.
These spectral shifts are consistent with literature reports,[22]
thus indicating that there is electronic coupling between the
carbazole substituent and the porphyrin ring, and the p con-
jugation of ZnPCPA and ZnPCTA becomes extended. The
spectral features of ZnPCPA and ZnPCTA with broad Soret
band and redshifted Q bands serve to increase the harvest-
ing of solar energy in a DSSC device, as explained in the
next section.
The absorption spectra of ZnPPA, ZnPCPA, and
ZnPCTA adsorbed on TiO2 films show broader absorption
peaks than those in solution (Figure 2b). Such a phenomenon
is commonly observed in the spectral response of other or-
ganic dyes, which might be ascribed to the interaction of the
anchoring groups of the dyes with the surface of TiO2.[23]
The wide absorption spectrum is an advantageous spectral
property for light harvesting of the solar spectrum. For the
fluorescence spectra (see the Supporting Information),
major emission bands of the porphyrins were observed at
607, 614, and 626 nm for ZnPPA, ZnPCPA, and ZnPCTA,
respectively. The trend for the ZnPCPA and ZnPCTA emis-
sions redshifted from that of ZnPPA is similar to the trend
of the Soret and Q-band absorption spectra.
the redox potential of the Iꢀ/I3 electrolyte (ꢀ4.80 eV).
Hence, dye regeneration should be thermodynamically fa-
vorable and could compete efficiently with recapture of the
injected electrons by the dye radical cations. The LUMO
levels of the dyes estimated from the relevant HOMOs and
energy gaps (Eogpt) obtained from the optical onset are
ꢀ3.12 eV for ZnPPA, ꢀ3.32 eV for ZnPCPA, and ꢀ3.21 eV
for ZnPCTA. The LUMOs are less negative than the con-
duction band (CB)-edge energy level of the TiO2 electrode
(ꢀ4.00 eV versus vacuum),[24] thus promising effective
charge injection from the excited dyes to the conduction
band of TiO2. Therefore, all new zinc–porphyrin dyes have
enough energetic driving force for efficient TiO2 and Iꢀ/I3
ꢀ
-based DSSCs. On the basis of the CV data, the energy gaps
(Eegle) of these dyes are also calculated to be in the range of
1.95–1.98 eV, which are close to those estimated from their
corresponding UV/Vis absorption spectra (Eogpt =1.98–
2.01 eV), thus indicating that the LUMO and HOMO levels
obtained by the electrochemical measurements are reliable
(Table 1).
The thermal properties of the zinc–porphyrin dyes
ZnPPA, ZnPCPA, and ZnPCTA were investigated by ther-
mogravimetric analysis (TGA), and the results suggested
that they are thermally stable materials, with temperature at
5% weight loss (T5d) well over 5108C (Table 1). The high
thermal stability of the dye is essential for the lifetime of
the solar cells.[25]
The electrochemical properties of solutions of ZnPPA,
ZnPCPA, and ZnPCTA were examined by cyclic voltamme-
try (CV) in CH2Cl2 with nBu4NPF6 as a supporting electro-
lyte (Figure 2c and Table 1). Their CV traces exhibit a single
process of quasi-reversible reduction at the same potential
(E1/2) of ꢀ1.39 V associated with the reduction of the zinc–
porphyrin ring to form the anion radical. Dyes ZnPPA and
ZnPCTA exhibit two quasi-reversible oxidation processes,
whereas ZnPCPA displays three quasi-reversible oxidation
Quantum Chemical Calculations
To gain insight into the geometrical, electronic, and optical
properties of ZnPPA, ZnPCPA, and ZnPCTA, we carried
&
&
4
Chem. Asian J. 2014, 00, 0 – 0
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ÝÝ These are not the final page numbers!

www.chemasianj.org
Vinich Promarak et al.
an electron donor, the end-capped carbazole can pump the
electron into the porphyrin and push the excited electrons
spatially in the direction of the TiO2 film. Considering the
conformation of the aryl rings that connect between the car-
bazole and porphyrin ring, the dihedral angles (f) between
these moieties will have a direct influence on such electron
transfers. As shown in Figure 4, the dihedral angles (f) be-
tween the phenyl linkage and porphyrin (f1 =68.428) and
carbazole (f2 =36.128) units of ZnPCPA are smaller than
those of the thiophenyl linkage and porphyrin (f1 =87.748)
and carbazole (f2 =44.058) units of ZnPCTA. These findings
imply that delocalization or injection of the p electron from
the meso-substituted carbazole into the porphyrin core in
ZnPCTA would be less efficient than in ZnPCPA.
Figure 3. Structures of porphyrins ZnPPA and ZnPCTA optimized by
B3LYP/6-31G(d,p).
It is very useful to determine the electronic distribution of
the HOMO and LUMO of the dyes, as these can offer a sen-
sible qualitative indication of the charge-separated state of
sensitizers. To generate an efficient charge-separated state,
the HOMO should be localized on the donor subunit and
the LUMO on the acceptor moiety.[27] The electron-density
distributions of ZnPPA, ZnPCPA, and ZnPCTA calculated
ACHTUNGTRENNUNG
out quantum chemical calculations. The ground-state geo-
metries of these dyes were fully optimized by the B3LYP/6-
31G(d) method[26] and are displayed in Figure 3 and the
Supporting Information. In all cases, the calculated ground-
state geometries reveal that the meso-substituted aryl rings
are twisted nearly perpendicular to the planar macrocyclic
zinc–porphyrin core; the dihedral angles are in the range of
approximately 68–888. The end-capped carbazoles of
ZnPCPA and ZnPCTA are twisted from the phenyl and thi-
ophenyl rings by about 36–448 and bent out of the plane of
the porphyrin ring, thus creating bulky substituents around
the porphyrin core. This could influence the p–p stacked ag-
gregation of the dye molecules and the amount of dye load-
ing on TiO2 films, the photoelectron injection efficiency
from the dye to the TiO2 electrode, and thereby the overall
conversion efficiency. As depicted in Figure 3, ZnPCPA and
ZnPCTA have bulkier molecular structures than ZnPPA. As
at the B3LYP/6-31GACTHNUTRGNEUNG(d,p) level are illustrated in Figure 5.
The frontier molecular orbital shows that in the LUMOs of
all dyes, the excited electrons localize on the entire p-conju-
gated anchoring moiety of bithiophenyl cyanoacrylic acid.
The electron-density distribution of LUMOs around an an-
choring group is known to influence the electronic coupling
between the excited adsorbed dye and 3d orbital of TiO2.[28]
In the HOMO of ZnPPA, p electrons are mainly delocalized
on the porphyrin ring, whereas in the HOMOs of ZnPCPA
and ZnPCTA, p electrons are delocalized over the p system
of the porphyrin ring as well as the carbazole aryl meso sub-
stituents. During photoexcitation, electrons are transferred
from the donor carbazole through the bithiophene cyanoa-
crylic acid to the surface-bound carboxylate. The HOMO
Figure 4. The selected bond lengths [ꢂ] and dihedral angles [8] of the dyes calculated at the B3LYP/6-31GACTHNUTRGNEU(GN d,p) level. R=bithiophenyl cyanoacrylic acid.
5
&
&
Chem. Asian J. 2014, 00, 0 – 0
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
These are not the final page numbers! ÞÞ

www.chemasianj.org
Vinich Promarak et al.
plemented in the DMol3 program.[29] The detail of the
method is the same as in our previous work.[27,30] By using
ꢀ
the bidentate binding mode of the carboxyl group (
ꢀ
COOH) on a TiO2 anatase (101) surface, the two Ti O
bonds of the zinc–porphyrin–(TiO2)38 complexes were found
to be 2.16 ꢂ with the calculated adsorption energy (Eads) of
ꢀ12.79–ꢀ13.14 kcalmolꢀ1 (see the Supporting Information),
thus indicating strong chemical binding. The HOMO and
ꢀ
ꢀ
LUMO orbitals of ZnPPA
complexes are illustrated in Figure 7. The electron distribu-
ACHTUTNGREN(GUN TiO2)38 and ZnPCPA ACHTUNGTRENNUNG(TiO2)38
Figure 5. The electronic distribution of the frontier molecular orbitals
(HOMO and LUMO) computed at the B3LYP/6-31G(d,p) level.
AHCTUNGTRENNUNG
and LUMO of all dyes were thoroughly separated, which
favors a facile charge migration from the donor to acceptor
upon irradiation. This is confirmed by the charge-density
difference between ground and excited states as shown in
Figure 6. Yellow and blue colors symbolize the decreased
Figure 6. A contour plot of the transition density difference (1S1ꢀ1S0)
calculated with the TD-PBE0/6-31G(d) basis set in CH2Cl2, The contour
threshold is 0.004 a.u.
ꢀ
ꢀ
Figure 7. The HOMO and LUMOs of ZnPPA
AHCTUNGTRENNUNG
ACHTUGNTRNE(UNNG TiO2)38 and ZnPCPA
and increased electron contributions of the lowest-energy
excitation (1S1ꢀ1S0), respectively. The density-difference
plots of ZnPPA, ZnPCPA, and ZnPCTA exhibit an affected-
ly strong charge-separation character. Charge gained on the
acceptor group after excitation is found in all cases. On the
basis of these calculations, the dipolar structure present in
the porphyrins of this study was expected to facilitate an ef-
ficient and rapid electron injection from the porphyrin excit-
ed state into the conduction band of TiO2. Moreover, within
the present series of dyes, the charge-transfer effects were
expected to be enhanced for ZnPCPA and ZnPCTA (which
bear three carbazole aryl substituents) relative to ZnPPA.
To confirm the efficient electron injection from the por-
phyrin excited state into the CB of TiO2 in the device, the
prototype system was modeled by dyes ZnPPA and
ZnPCPA adsorbed onto the (TiO2)38 cluster. The optimiza-
tions were carried out by means of the Perdew–Burke–Ern-
zerhof (PBE)/double-numeric polarized (DNP) method im-
ꢀ
tions in the HOMO orbital of the ZnPPA ACTHNUGTRNEG(UN TiO2)38 complex
are mainly localized on the porphyrin core, whereas in the
ꢀ
HOMO of the ZnPCPA
(TiO2)38 complex, they are local-
ized on both the porphyrin core and carbazole phenyl sub-
stituents. In the LUMO orbital of both complexes the entire
excited electrons are distributed on the TiO2 cluster. The re-
sults indicate that excited electrons efficiently transfer from
the dye sensitizer to the conduction band of the TiO2 cluster
when the dye is absorbed onto the TiO2 film under illumina-
tion. This character is defined as an interfacial direct
charge-transfer injection mechanism.[27,30] This behavior of
the electron transfer is highly consistent with the charge-
transfer transition of isolated dyes, which is contributed by
67–69% (H!L). The above results imply that dyes ZnPPA
and ZnPCPA with bithiophene as the conjugated bridge and
&
&
6
Chem. Asian J. 2014, 00, 0 – 0
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ÝÝ These are not the final page numbers!

www.chemasianj.org
Vinich Promarak et al.
cyanoacrylic acid as the anchoring moiety have sufficient
potential to inject an electron from the porphyrin core into
the conduction band of TiO2 film.
Photovoltaic Properties
To investigate the effects of the meso substituents on the
photovoltaic performances of the porphyrin dyes, the
DSSCs using the newly synthesized dyes ZnPPA, ZnPCPA,
and ZnPCTA as sensitizers were fabricated and their per-
formances were measured under AM 1.5G conditions at
100 mWcmꢀ2. The solar cells with an effective area of
0.25 cm2 were composed of TiO2 film with 14 mm (9 mm
transparent+5 mm scattering) thickness, the adsorbed dye
(from 6ꢁ10ꢀ4 m solutions), a redox electrolyte (Z960 electro-
lyte: 1.0m 1,3-dimethylimidazolium iodide (DMII), 0.1m
guanidinium thiocyanate (GuSCN), 0.03m I2, 0.05m LiI, and
0.5m tert-butypyridine (4-TBP) in the mixed solvent of ace-
tonitrile (CH3CN) and valeronitrile (VN) (85:15 v/v)), and
a platinum on fluorine-doped SnO2 (FTO) counter elec-
trode. To evaluate the photovoltaic performance, five cells
were prepared and measured under the standard conditions
for each dye. The incident monochromatic photon-to-cur-
rent conversion efficiency (IPCE) spectra and current-densi-
ty–voltage (J–V) characteristics are plotted in Figure 8. The
relevant photovoltaic parameters (average values) of the
short-circuit current (Jsc), open-circuit voltage (Voc), fill
factor (ff), and power conversion efficiency (h) are listed in
Table 2. According to these results, it is clear that the photo-
voltaic performances of the DSSCs can be clearly affected
by the modifications on the meso positions of the porphyrin
ring. Solar cells fabricated with the dyes ZnPCPA and
ZnPCTA that contain carbazole-N-yl benzene or carbazole-
N-yl thiophene as the meso substituents, respectively, show
significantly higher power conversion efficiencies than the
cell fabricated with pristine zinc–porphyrin ZnPPA. The
overall performances of the DSSCs are in the order of
ZnPCPA (h=6.25%)>ZnPCTA (h=5.09%)>ZnPPA (h=
2.51%). The ZnPCPA-based cell exhibits the best perform-
ances (highest h), clearly due to its high Jsc (13.38 mAcmꢀ2),
Voc (0.66 V), and IPCE efficiency (>70% in the range 360–
510 nm with a maximum of 94% at 442 nm), whereas the
low h value of the ZnPPA-based cell derives from its low Jsc
(6.23 mAcmꢀ2), Voc (0.57 V), and low IPCE value. The Jsc of
the ZnPPA-based DSSC is lower than ZnPCPA and
Figure 8. a) J–V characteristics and b) IPCE spectra of the DSSCs.
ZnPCTA, which can be attributed to the poor charge-injec-
tion efficiency of the dye toward the TiO2 film. The Voc
values of ZnPCPA- and ZnPCTA-based solar cells (Voc =
0.66 V) are higher than ZnPPA (Voc =0.57 V), thereby sug-
gesting that charge-recombination processes of the injected
ꢀ
electrons in TiO2 and triiodide (I3 ) in the electrolyte of
those cells are very diminished.[31] These observations could
be explained by the effect of dye aggregation and electron-
donating carbazole group attached at the meso positions of
the porphyrin core.
The analyses of the optimum dye adsorption amounts on
the TiO2 films by the desorption method[32] reveal that the
amount of dye loading on the TiO2 photoanode of the
ZnPCPA- and ZnPCTA-based DSSCs (1.33–1.50ꢁ
1017 molecule cmꢀ2) are lower than that of the ZnPPA-based
cell (2.35ꢁ1017 molcmꢀ2), thus confirming that the former
dyes possess more bulky molecular structures (Table 2). Ac-
cordingly, the DSSC fabricated with ZnPPA dye as sensitiz-
Table 2. Photophysical, physical, and electrochemical data of the zinc–porphyrin dyes.
[a]
Dye
Amount of dye adsorbed [molecule cmꢀ2
]
Jsc [mAcmꢀ2
]
Voc [V]
ff
h [%] RCT [W] at ꢀ0.65 V t [ms] at ꢀ0.65 V
ZnPPA
ZnPCPA
ZnPCTA
ZnPPA+CDCA (1:2)
ZnPCPA+CDCA (1:2)
ZnPCPA+CDCA (1:5)
N719[b]
2.35ꢁ1017
1.50ꢁ1017
1.33ꢁ1017
1.97ꢁ1017
1.02ꢁ1017
8.91ꢁ1016
6.85ꢁ1016
6.28
13.38
11.02
7.93
12.66
11.99
15.54
0.57
0.66
0.66
0.63
0.67
0.66
0.77
0.70
0.71
0.70
0.70
0.71
0.69
0.68
2.51
6.25
5.09
3.50
5.99
5.51
8.19
25.26
79.95
81.96
–
–
–
5.51
16.52
17.64
–
–
–
162.44
17.22
[a] Measured by the desorption method.[32] [b] Electrolyte: A6141 electrolyte (0.6m butylmethylimidazolium iodide (BMII), 0.03m I2, 0.5m 4-TBP, 0.1m
GuSCN in CH3CN/VN (85:15 v/v).
7
&
&
Chem. Asian J. 2014, 00, 0 – 0
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
These are not the final page numbers! ÞÞ

www.chemasianj.org
Vinich Promarak et al.
er will experience a greater tendency to form p–p-stacked
dye aggregates on the TiO2 surface than that of ZnPCPA
and ZnPCTA. It has been known that dye aggregation can
directly affect photoelectron injection efficiency of the dye
and thereby the overall conversion efficiency.[33] The break-
up of p-stacked aggregates might improve electron injection
yield and thus Jsc values. The influence of dye aggregation
on TiO2 surfaces for ZnPPA and ZnPCPA dyes was there-
fore further investigated by coadsorption of ZnPPA and
ZnPCPA with chenodeoxycholic acid (CDCA) (Table 2).
The cell performance of ZnPPA improved upon addition of
CDCA at a dye/CDCA ratio of 1:2, whereas that of
ZnPCPA decreased in the presence of CDCA. The addition
of CDCA increased both the Jsc and Voc of the ZnPPA/
CDCA-based cell. This improvement in Jsc would take place
through the coadsorbed CDCA to hinder the formation of
dye aggregates and increase the electron injection yield and
modify the TiO2 electrode surface to increase electron inter-
ception,[34] whereas the increase in Voc would be attributed
to the decrease in charge recombination. The Jsc of the
device has a maximum value at a dye/CDCA ratio of 1:2.
The existence of CDCA, however, systematically decreases
the amount of dye loading on the TiO2 surface and reduces
electron injection from dye to TiO2, thereby resulting in the
lower Jsc in the case of ZnPCPA. The coadsorption of
CDCA thus fails to improve the cell performance of
ZnPCPA, unlike for ZnPPA and other organic sensitizers.[35]
The overall performance of a porphyrin-based DSSC is thus
a subtle balance between these factors. It is noticeable that
the efficiency of the ZnPPA/CDCA-based solar cell (h=
3.50%) is still lower than that of ZnPCPA- and ZnPCTA-
based cells (h=5.09–6.24%), which suggests that the higher
efficiencies of the latter devices might not only result from
lower dye aggregations on TiO2 owing to bulky carbazole
substituents but also come from an electron-donating prop-
erty of the carbazole.
DSSCs. Moreover, the bulkiness of the molecular structures
of ZnPCPA and ZnPCTA due to the carbazole substituents
might be beneficial in retarding the electron transfer from
TiO2 to the oxidized dye or electrolyte, which would en-
hance the Voc value. The slightly larger Jsc of the ZnPCPA-
based cell than ZnPCTA can be tentatively attributed to
a better electron transfer from the carbazole phenyl group
to the acceptor moiety than that of the carbazole thiophenyl
group as described in quantum chemical calculations.
The effect of the meso substituent of carbazoles on the es-
sential interfacial charge-transfer processes in the DSSCs
was also evaluated by electrochemical impedance spectros-
copy (EIS) analyses. In general, the Voc of a DSSC is related
to the electron transport at the interfaces or the electron
lifetime in the cell.[37] The EIS was measured in the dark to
describe the correlation between Voc and the molecular
structure of a dye. The equivalent circuit is shown in
Figure 9. The Nyquist plots of the DSSCs are shown by two
semicircles (Figure 10a).
Figure 9. Equivalent circuit for the DSSCs.
The small and large semicircles, separately located in the
high- and middle-frequency regions, are assigned to the
charge transfer at the Pt counter electrode/electrolyte and
the TiO2/electrolyte interface, respectively.[38] The charge-re-
combination resistance (RCT) at the TiO2 surface can be de-
duced by fitting curves from the middle-frequency range
using ZMAN software (Figure 10c and Table 2). The value
of RCT is related to the charge-recombination rate between
The large Jsc values of ZnPCPA- and ZnPCTA-based
solar cells relative to that of the ZnPPA-based cell might
arise from the effect of the broadly covering IPCE spectra.
The IPCE spectra (Figure 8b) of the DSSCs that replicate
absorption features of zinc–porphyrin are consistent with
the measured Jsc; they increase in the order of ZnPCPA
ꢀ
the injected electron and electron acceptor I3 in the elec-
trolyte, estimated by radius of the larger semicircle. The
ZnPCPA- and ZnPCTA-based DSSCs (RCT =79.26 and
81.96 W) exhibit significantly larger RCT values than the
ZnPPA DSSC (RCT =25.26 W), thus implying the slow rate
of charge recombination or minor charge recombination at
the TiO2/electrolyte interface, with a consequently high Voc
for these cells. The RCT values of these DSSCs appear to
agree with their Voc values. The decrease in RCT indicates
the high charge loss in the TiO2/electrolyte interface and
consequently a lower Voc value. The difference in Voc of
these DSSCs can also be elucidated by the electron lifetime.
Figure 10b shows the Bode plot for the DSSCs based on
these three dyes. The position of the lower frequency peaks,
which correspond to the large semicircle (Figure 10a, right)
in the Nyquist plots, can be related to the electron lifetime
(t) of the DSSCs. The electron lifetime can be extracted
from the angular frequency (wmin) at the mid-frequency
peak in the Bode phase plot using t=1/wmin (Figure 10d and
Table 2).[39] The t values of ZnPCPA- and ZnPCTA-based
(Jsc =13.38 mAcmꢀ2)>ZnPCTA
(Jsc =11.02 mAcmꢀ2)>
ZnPPA (Jsc =6.23 mAcmꢀ2). All three electron-donating car-
bazole groups attached at the meso positions of the zinc–
porphyrin core of ZnPCPA and ZnPCTA not only extend
the absorption spectrally to a region of greater wavelength
but also push the excited electrons spatially toward the TiO2
film for an enhanced charge separation, charge-injection ef-
ficiency of the dye, and thus Jsc, as observed in the DFT cal-
culations. The N-carbazole substituents in ZnPCPA and
ZnPCTA can also reduce a recombination reaction between
conduction-band electrons in TiO2 and electron-accepting
ꢀ
ꢀ
ꢀ
I3 , thus leading to the I2 radical anion, because I3 might
attach to the positively charged N atom of the carbazole
moiety far from the TiO2 surface.[36] This process manifests
itself as a dark current in limiting the photovoltage of the
&
&
8
Chem. Asian J. 2014, 00, 0 – 0
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ÝÝ These are not the final page numbers!

www.chemasianj.org
Vinich Promarak et al.
pushes the excited electrons
spatially toward the TiO2 film
for an improved charge separa-
tion, whereas the large Voc
values
in
ZnPCPA
and
ZnPCTA come from the bulky
structure of the carbazole aryl
groups that can effectively sup-
press the porphyrin aggrega-
tions on the surface of the TiO2
films to result in the increase of
the injected electrons and
modification of the TiO2 elec-
trode surface to increase elec-
tron interception, and thus di-
minish
a
recombination be-
ꢀ
tween I3 and conduction-band
electrons. Among the three syn-
thesized
dye
molecules,
ZnPCPA that contains carba-
zole phenyl as the meso sub-
stituent shows the maximum
power conversion efficiency of
6.24%
(Jsc =13.38 mAcmꢀ2,
Figure 10. a) Nyquist plots and b) Bode-phase plots of the DSSCs. Plots of c) RCT and d) t at different bias vol-
tages (Vbias) of the DSSCs.
Voc =0.66 V, ff=0.71) under si-
mulated AM 1.5G irradiation
(100 mWcmꢀ2). Our results
solar cells (t=16.52 and 17.64 ms) are higher than that of
ZnPPA (t=5.51 ms), which is consistent with the trend of
their Voc values. The high t values for ZnPCPA- and
ZnPCTA-based solar cells support more effective suppres-
thus indicate that the design of porphyrin dyes with bulky
or/and electron-donating groups to avoid dye aggregation
and improve the charge injection is effective in promoting
cell performance for future porphyrin-based DSSC.
ꢀ
sion of the recombination of the injected electrons with I3
in the electrolyte by alternation of HOMO of the sensitizer,
which leads to the enlargement of the photocurrent and
photovoltage and to considerable improvement of the cell
efficiency.
Experimental Section
Materials and Methods
All chemicals were purchased from Aldrich, Acros, or Thai companies
and used as received. THF and CH2Cl2 for CV measurements were dis-
tilled according to the standard methods. 1H and 13C NMR spectra were
recorded with a Bruker AVANCE 300 MHz spectrometer. IR spectra
were measured with a Perkin–Elmer FTIR spectrum RXI spectrometer.
UV/Vis spectra were recorded in CH2Cl2 with a Perkin–Elmer UV
Lambda 25 spectrometer. Diffuse reflectance spectra of dye adsorbed on
TiO2 were measured at room temperature with a Shimadzu UV-3101
spectrophotometer. BaSO4 was used as a standard. The measured reflec-
tance spectra were then converted into absorption spectra by the Kubel-
ka–Munk method. Thermogravimetric analysis (TGA) was performed
with a Rigaku TG-DTA 8120 thermal analyzer with heating rate of
108Cminꢀ1 under an N2 atmosphere. CV measurements were performed
with an Autolab potentiostat PGSTAT 12 with a three-electrode system
(platinum counter electrode, glassy carbon working electrode, and Ag/
AgCl reference electrode) in CH2Cl2 under an Ar atmosphere with
nBu4NPF6 as a supporting electrolyte at scan rate of 50 mVsꢀ1. The con-
centration of analytical materials and the electrolyte were 10–3m and
0.1m, respectively. Melting points were measured with an Electrothermal
IA 9100 series digital melting-point instrument and are uncorrected.
Conclusion
In summary, we have demonstrated the design strategy and
synthesis of novel meso-substituted zinc–porphyrin dyes that
contain arylenes (benzene, phenyl carbazole, and thiophenyl
carbazole) as donor and bithiophenyl cyanoacrylic acid as
a p-linkage acceptor. The influence of the arylene substitu-
ents is clearly observed by the redshift in UV/Vis absorption
spectra (both Soret and Q bands) and the shift of the redox
potentials of the dyes. The DSSCs made of porphyrins with
electron-donating carbazole substituents (ZnPCPA and
ZnPCTA) show better performance than the ZnPPA refer-
ence cell. The superlative power conversion efficiencies of
the ZnPCPA and ZnPCTA solar cells are due to their large
Jsc and Voc values. The large Jsc values in ZnPCPA and
ZnPCTA arise from their much broader and redshifted
IPCE spectra because of the effective electronic coupling
between the carbazole aryl groups and the porphyrin core.
The electron-donating properties of the carbazole also
MALDI-TOF mass spectra were recorded with
(Bremen, Germany) Autoflex II matrix-assisted laser desorption/ioniza-
tion/time-of-flight mass spectrometer (BIFEX).
a Bruker Daltonics
9
&
&
Chem. Asian J. 2014, 00, 0 – 0
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
These are not the final page numbers! ÞÞ

www.chemasianj.org
Vinich Promarak et al.
Synthesis of Zinc–Porphyrins 3, 8, and 9
132.67, 134.62, 135.75, 137.37, 138.08, 183.21, 139.38, 141.06, 141.09,
141.65, 143.30, 145.84, 147.22, 150.27, 150.46, 150.69, 151.03, 182.37 ppm;
IR (KBr): n˜ =2955, 1702, 1585, 1512, 1489, 1473, 1364, 1262, 999,
Aryl aldehydes 1, 6, or 7 (15.70 mmol), 5-bromothiophene-2-carbalde-
hyde (2) (5.23 mmol), and pyrrole (20.93 mmol) were places in a dry
round-bottomed flask and dissolved in CH2Cl2 (600 mL). The solution
was degassed with N2. TFA (5.23 mmol) was added, and the reaction mix-
ture stirred in the dark under an N2 atmosphere for 3 h. DDQ
(7.851 mmol) was added, and the mixture was stirred for 1 h. Na2CO3
(2.0 g) was added, and the mixture was filtered through a plug of silica
808 cmꢀ1
;
HRMS (ESI-TOF): m/z calcd for C107H97N7OS2Zn [M]+:
1623.6487; found: 1623.8261.
Compound 11 was yielded as
a purple solid (62%). M.p.>2508C;
1H NMR (300 MHz, CDCl3): d=1.56 (s, 54H), 7.39 (s, 1H), 7.64–7.76 (m,
11H), 7.89–7.93 (m, 6H), 8.00–8.04 (m, 4H), 8.24 (s, 6H), 9.35 (d, J=
4.6 Hz, 2H), 9.43 (d, J=4.6 Hz, 2H), 9.49 (s, 4H), 9.65 ppm (s, 1H);
13C NMR (75 MHz, CDCl3): d=29.74, 32.10, 32.31, 34.90, 109.94, 112.16,
113.25, 113.35, 116.47, 123.19, 123.27, 123.86, 124.19, 125.26, 132.23,
132.31, 132.54, 134.72, 137.40, 138.28, 140.40, 140.44, 140.87, 141.42,
141.59, 143.95, 145.40, 147.15, 151.07, 151.53, 151.60, 151.62, 182.26 ppm;
by eluting with CH2Cl2. The solvent was reduced, and ZnACHTNUGTRNEUNG(OAc)2·2H2O
(7.851 mmol) and MeOH (50 mL) were added. The reaction mixture was
heated under reflux conditions for 1 h. The solvents were removed to
dryness, and the crude product was purified by column chromatography
over silica gel by eluting with a mixture of CH2Cl2/hexane (20:80) and re-
crystallization from CH2Cl2/MeOH to give 3 as a purple solid (8%).
IR (KBr): n˜ =2946, 1633, 1558, 1488, 1365, 1286, 1166, 973, 788 cmꢀ1
;
HRMS (ESI-TOF): m/z calcd for C101H91N7OS5Zn [M]+: 1641.5180;
1
M.p.>2508C; H NMR (300 MHz, CDCl3): d=1.54 (s, 54H), 7.48 (d, J=
found: 1641.5194.
3.6 Hz, 1H), 7.68 (d, J=3.6 Hz, 1H), 7.81–7.82 (m, 3H), 8.10 (d, J=
1.6 Hz, 6H), 9.02 (s, 4H), 9.03 (d, J=4.7 Hz, 2H), 9.21 ppm (d, J=
4.7 Hz, 2H); 13C NMR (75 MHz, CDCl3): d=31.45, 31.50, 31.76, 35.06,
109.79, 113.46, 120.91, 123.01, 123.72, 129.08, 129.56, 129.69, 131.16,
132.15, 132.82, 133.13, 141.64, 141.68, 145.82, 148.58, 148.64, 150.26,
150.51, 150.79, 150.92 ppm; IR (KBr): n˜ =2963, 1592, 1475, 1363, 1248,
801, 713 cmꢀ1; HRMS (ESI-TOF): m/z calcd for C66H73BrN4SZn [M]+:
1096.4031; found: 1096.4064.
Synthesis of Zinc–Porphyrin Dyes ZnPPA, ZnPCPA, and ZnPCTA
A mixture of 4, 10, or 11 (0.25 mmol), 2-cyanoacetic acid (5.03 mmol),
and piperidine (0.25 mmol) in MeOH (20 mL) was heated under reflux
conditions for 3 h. After cooling, the mixture was added to water
(50 mL), extracted with CH2Cl2 (2ꢁ50 mL), washed with water (50 mL),
brine solution (50 mL), dried over anhydrous Na2SO4, and filtered. The
solvent was removed to dryness, and the crude product was purified by
column chromatography over silica gel by eluting with a mixture of
CH2Cl2/MeOH and recrystallization from CH2Cl2/MeOH to give ZnPPA
as a purple solid (70%). M.p.>2508C; 1H NMR (300 MHz, CDCl3): d=
1.59 (s, 54H), 6.07 (s, 1H), 7.06 (d, J=2.9 Hz, 1H), 7.53 (d, J=2.9 Hz,
1H), 7.84 (s, 3H), 8.17 (d, J=7.2 Hz, 6H), 9.04 (s, 6H), 9.27 ppm (d, J=
4.4 Hz, 2H); 13C NMR (75 MHz, CDCl3): d=29.76, 31.83, 31.84, 35.11,
110.05, 120.71, 122.59, 122.63, 122.76, 13.30, 123.68, 129.47, 129.72, 129.88,
131.14, 132.02, 132.35, 132.63, 133.16, 133.99, 138.19, 140.83, 142.16,
144.76, 148.45, 148.50, 150.19, 150.46, 150.63, 150.82, 161.62 ppm; IR
(KBr): n˜ =3425, 2962, 2220, 1592, 1462, 1362, 1247, 1218, 1132, 1002,
798 cmꢀ1; HRMS (ESI-TOF): m/z calcd for C74H78N5O2S2Zn [M+H]+:
1196.4888; found: 1196.4882.
1
Compound 8 was yielded as a purple solid (6%). M.p.>2508C; H NMR
(300 MHz, CDCl3): d=1.56 (s, 54H), 7.52 (s, d, J=3.6 Hz, 1H), 7.64 (d,
J=8.7 Hz, 6H), 7.73 (d, J=3.6 Hz, 1H), 7.81 (d, J=8.4 Hz, 6H), 8.01 (d,
J=8.1 Hz, 6H), 8.28 (s, 6H), 8.45–8.49 (m, 6H), 9.17–9.23 (m, 6H),
9.32 ppm (d, J=4.8 Hz, 2H); 13C NMR (75 MHz, CDCl3): d=32.09,
34.85, 109.50, 116.47, 121.04, 123.75, 123.86, 124.63, 129.28, 131.93, 132.26,
132.48, 133.47, 135.71, 138.00, 139.34, 141.03, 141.17, 143.25, 150.18,
150.44, 150.64, 151.26 ppm; IR (KBr): n˜ =2961, 1592, 1477, 1360, 1249,
807 cmꢀ1
;
HRMS (ESI-TOF): m/z calcd for C102H94BrN7SZn [M]+:
1591.5766; found: 1592.1220.
1
Compound 9 was yielded as a purple solid (5%). M.p.>2508C; H NMR
(300 MHz, CDCl3): d=1.54 (s, 54H), 7.52–7.57 (m, 2H), 7.62–7.72 (m,
9H), 7.87 (d, J=9.0 Hz, 6H), 8.00 (t, J=3.9 Hz, 3H), 8.22 (s, 6H), 9.25
(d, J=4.5 Hz, 1H), 9.29 (d, J=4.8 Hz, 1H), 9.40 (t, J=5.1 Hz, 2H), 9.46–
9.47 ppm (m, 4H); 13C NMR (75 MHz, CDCl3): d=29.71, 32.06, 34.87,
109.89, 116.42, 123.17, 123.79, 124.15, 132.27, 140.38, 140.72, 143.89,
151.56 ppm; IR (KBr): n˜ =2961, 1591, 1478, 1362, 1251, 802 cmꢀ1; HRMS
(ESI-TOF): m/z calcd for C96H88BrN7S4Zn [M]+: 1609.4459; found:
1609.4583.
Compound ZnPCPA was yielded as a purple solid (68%). M.p.>2508C;
1H NMR (300 MHz, CDCl3): d=1.54 (s, 54H), 7.43 (brs, 1H), 7.63 (d,
J=7.8 Hz, 7H), 7.80 (d, J=8.1 Hz, 7H), 7.99–8.04 (m, 8H), 8.28 (s, 6H),
8.43–8.51 (m, 6H), 9.17 (d, J=6.6 Hz, 6H), 9.35 ppm (d, J=3.9 Hz, 2H);
13C NMR (75 MHz, CDCl3): d=29.72, 32.08, 34.84, 109.51, 110.56, 116.47,
121.09, 121.64, 123.76, 123.85, 124.60, 125.81, 131.78, 132.24, 132.50,
132.66, 134.91, 135.73, 137.96, 138.02, 139.31, 140.94, 141.03, 143.25,
150.20, 150.36, 150.61, 150.87, 166.45 ppm; IR (KBr): n˜ =3450, 2955,
2221, 1702, 1585, 1512, 1489, 1473, 1364, 1262, 999, 808 cmꢀ1; HRMS
(ESI-TOF): m/z calcd for C110H99N8O2S2Zn [M+H]+: 1691.6624; found:
1691.6512.
Synthesis of Zinc–Porphyrin Aldehydes 4, 10, and 11
A mixture of 3, 8, or 9 (0.090 mmol), 5-formyl-2-thiopheneboronic acid
(0.091 mmol), [PdACHTUNGTRENNUNG(PPh3)4] (4.50 mmol), and 2m Na2CO3 (aqueous, 5 mL)
in THF (15 mL) was degassed with N2 for 5 min. The mixture was stirred
under reflux conditions for 18 h. After cooling, the mixture was extracted
with CH2Cl2 (2ꢁ50 mL), washed with water (50 mL) and brine solution
(50 mL), dried over Na2SO4 anhydrous, and filtered. The solvent was re-
moved to dryness, and the crude product was purified by column chroma-
tography over silica gel by eluting with a mixture of CH2Cl2/hexane
(30:70) and recrystallization from CH2Cl2/MeOH to give 4 as a purple
solid (65%). M.p.>2508C; 1H NMR (300 MHz, CDCl3): d=1.54 (s,
54H), 7.44 (d, J=5.6 Hz, 1H), 7.73 (d, J=3.9 Hz, 1H), 7.76 (d, J=
3.5 Hz, 1H), 7.81 (s, 3H), 7.87 (brs, 1H), 8.10 (s, 6H), 9.02 (s, 4H), 9.05
(d, J=4.8 Hz, 2H), 9.26 (d, J=4.7 Hz, 2H), 9.87 ppm (s, 1H); 13C NMR
(75 MHz, CDCl3): d=31.75, 35.06, 120.95, 124.25, 125.14, 129.66, 131.07,
132.20, 132.56, 132.89, 137.50, 141.71, 147.47, 148.65, 150.57, 182.53 ppm;
IR (KBr): n˜ =2963, 1647, 1460, 1220, 1004, 796 cmꢀ1; HRMS (ESI-TOF):
m/z calcd for C71H76N4OS2Zn [M]+: 1128.4752; found: 1128.4786.
Compound ZnPCTA was yielded as a purple solid (59%). M.p.>2508C;
1H NMR (300 MHz, CDCl3/[D5]pyridine): d=1.49 (s, 54H), 7.44–7.82 (m,
23H), 8.14 (d, J=10.2 Hz, 6H), 9.24–9.31 ppm (m, 8H); 13C NMR
(75 MHz, CDCl3): d=29.72, 32.03, 34.75, 109.86, 116.28, 123.77, 124.10,
132.21, 140.14, 141.41, 143.71, 150.84, 162.00 ppm; IR (KBr): n˜ =3411,
2952, 2222, 1619, 1555, 1482, 1362, 1258, 1116, 973, 791 cmꢀ1; HRMS
(ESI-TOF): m/z calcd for C104H93N8O2S5Zn [M+H]+: 1709.5316; found:
1709.5298.
Quantum Chemical Calculations
All calculations were performed by the Gaussian 09 software in CH2Cl2
solvent by the conductor-like polarizable continuum model (C-PCM).[26]
The energy or geometry optimizations were carried out by the B3LYP/6-
31G
ACHTUNGERTN(NUNG d,p) method. The ground- to excited-state excitation energies were
calculated at the TD-B3LYP/6-31GACTHUNGTRNE(UNG d,p) level in CH2Cl2. The orbitals of
Compound 10 was yielded as
a purple solid (58%). M.p.>2508C;
the dye-(TiO2)[38] complex were calculated by PBE0 with the 6-31G(d)
basis set for C, O, S, Ti, N, and H atoms and LANL2DZ for the Zn atom
using DMol3.[29]
1H NMR (300 MHz, CDCl3): d=1.56 (s, 54H), 7.49 (d, J=3.9 Hz, 1H),
7.64 (d, J=8.7 Hz, 6H), 7.76 (d, J=3.9 Hz, 1H), 7.81–7.84 (m, 7H), 7.96
(d, J=3.6 Hz, 1H), 8.01 (d, J=8.1 Hz, 6H), 8.28 (s, 6H), 8.47–8.51 (m,
6H), 9.20–9.22 (m, 6H), 9.37 (d, J=4.8 Hz, 2H), 9.90 ppm (s, 1H);
13C NMR (75 MHz, CDCl3): d=29.73, 32.12, 34.88, 109.53, 110.72, 116.50,
121.11, 121.66, 123.82, 123.88, 124.22, 124.66, 125.26, 131.87, 132.29,
&
&
10
Chem. Asian J. 2014, 00, 0 – 0
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ÝÝ These are not the final page numbers!

www.chemasianj.org
Vinich Promarak et al.
Fabrication and Testing of DSSC Devices
The TiO2 photoanodes were prepared by using a previously reported pro-
Acknowledgements
This work was supported by the National Science and Technology Devel-
opment Agency (SPA A5: Solar Cell (10ISRA05)), the Thailand Re-
search Fund (DBG 5580001), and the Center for Innovation in Chemistry
(PERCH-CIC).
cedure.[40] Fluorine-doped SnO2 (FTO) conducting glasses (15 Wsqꢀ1
,
TEC15, Pilkington) were used for transparent conducting electrodes. The
double nanostructured thick films (ꢁ9+5 mm thickness) that consisted
of a transparent (PST-18NR, JGC Catalysts and Chemical Ltd.) and scat-
tering (PST-400C, JGC Catalysts and Chemical Ltd.) TiO2 layers were
screen-printed on TiCl4-treated FTO. The thickness of the TiO2 film was
controlled by selection of screen mesh size and repetition of printing.
Prior to dye sensitization, the TiO2 electrode with cell geometry of 0.5ꢁ
0.5 cm2 were treated with an aqueous solution of 4ꢁ10ꢀ2 m TiCl4 at 708C
in a water saturation atmosphere, heated to 4508C for 30 min, and then
cooled to 808C. The TiO2 electrodes were immersed in the dye solution (
ꢁ6ꢁ10ꢀ4 m in EtOH) in the dark at room temperature for 24 to 48 h to
stain the dye onto the TiO2 surfaces. Excess amounts of dye were re-
moved by rinsing with an appropriate solvent. To ensure maximum dye
adsorption on TiO2 film, higher dye concentrations (>10-fold) than that
used for the dye adsorption experiments were used. The Pt counter elec-
trode was prepared on a predrilled 8 Wsqꢀ1, TEC8, FTO glass (Pilking-
ton) by means of the thermal decomposition of 7ꢁ10ꢀ3 m H2PtCl6 in iso-
propanol solution at 3858C. The dye-adsorbed TiO2 photoanode and Pt
counter electrode were assembled into a sealed cell by heating a Meltonix
1170-25 film (25 mm thickness, Solaronix) gasket as a spacer between the
electrodes. An electrolyte solution of Z960 electrolyte that comprised
1.0m 1,3-dimethylimidazolium iodide (DMII), 0.1m guanidinium thiocya-
nate (GuSCN), 0.03m I2, 0.05m LiI, and 0.5m tert-butypyridine (4-TBP)
in a mixed solvent of acetonitrile (CH3CN) and valeronitrile (VN) (85:15
v/v) was filled through the predrilled hole by a vacuum backfilling
method. The hole was capped by using hot-melt sealing film (Meltonix
1170-25, 25 mm thickness, Solaronix) and a thin glass cover. Finally, con-
ducting tape (Scotch 3M) and silver paint (SPI supplies) were coated on
the electrodes to enhance the electric contact. The reference cell with
N719 dye as the sensitizer was prepared for comparison. For each dye,
five devices were fabricated and measured for consistency, and the aver-
aged cell data was reported. The J–V of the DSSCs was measured with
a Keithley 2400 source meter unit in a four-terminal sense configuration.
The data were averaged from forward and backward scans with a bias
step and a delay time of 10 mV and 40 ms, respectively, according to the
method of Koide and Han.[41] Simulation of sunlight was provided by
a Newport sun simulator 96000 equipped with an AM 1.5G filter. To
minimize the error of measurements, the irradiation intensity of
100 mWcmꢀ2 was approximated with a calibrated BS-520 Si photodiode
(Bunnkoukeiki Co., Ltd., Japan); its spectral response was very similar
to that of the DSSCs. The spectral output of the lamp was also matched
to the standard AM 1.5G solar spectrum in the region of 350–750 nm
with the aid of a KG-5 filter with a spectral mismatch less than 2% as re-
ported by Ito et al.[42] IPCE of the device under short-circuit conditions
were performed with an Oriel 150 W Xe lamp fitted with a Cornerstone
TM 130 1/8m monochromator as a monochromatic light source, a New-
port 818-UV silicon photodiode as power density calibrator, and a Keith-
ley 6485 picoammeter. All measurements were performed using a black
plastic mask with an aperture area of 0.25 cm2 and no mismatch correc-
tion for the efficiency conversion data. Electrochemical impedance spec-
tra (EIS) were analyzed with an EA163 eDAQ potentiostat integrated
with an ERZ100 eDAQ Z100 electrochemical impedance analyzer at
a bias potential of ꢀ0.65 V in the dark. Nyquist plots of all DSSCs were
recorded over a frequency range of 50 mHz–100 kHz with an amplitude
of 10 mV and fitted using ZMAN software (WonTech Co. Ltd.) and an
equivalent circuit RsꢀRPt j jQPtꢀRCT j jQCT. The Rs denotes the ohmic
series resistance of the cell, RPt stands for charge resistance at the Pt/elec-
trolyte electrode, and RCT represents the charge-recombination resistance
at the TiO2/electrolyte interface. The Q parameters are the constant
phase elements.
[1] B. O’Regan, M. Grꢃtzel, Nature 1991, 353, 737–740; I. Chung, B.
Lee, J. He, R. P. H. Chang, M. G. Kanatzidis, Nature 2012, 485, 486–
489.
[2] a) S.-Y. Ho, C. Su, C.-Y. Li, K. Prabakaran, M.-T. Shen, Y.-F. Chen,
W.-C. Chang, Y. S. Tingare, S. Akula, S.-H. Tsai, W.-R. Li, Chem.
Asian J. 2013, 8, 2196–2203; b) Y. Qin, Q. Peng, Int. J. Photoenergy
2012, 291579; c) M. K. Nazeeruddin, P. Pꢄchy, T. Renouard, S. M.
Zakeeruddin, R. Humphry-Baker, P. Comte, P. Liska, L. Cevey, E.
Costa, V. Shklover, L. Spiccia, G. B. Deacon, C. A. Bignozzi, M.
Grꢃtzel, J. Am. Chem. Soc. 2001, 123, 1613–1624; d) F.-R. Dai, Y.-
C. Chen, L.-F. Lai, W.-J. Wu, C.-H. Cui, G.-P. Tan, X.-Z. Wang, J.-T.
Lin, H. Tian, W.-Y. Wong, Chem. Asian J. 2012, 7, 1426–1434.
[3] a) R. Deshpande, B. Wang, L. Dai, L. Jiang, C. S. Hartley, S. Zou,
H. Wang, L. Kerr, Chem. Asian J. 2012, 7, 2662–2669; b) Y.-C.
Chang, C.-L. Wang, T.-Y. Pan, S.-H. Hong, C.-M. Lan, H.-H. Kuo,
C.-F. Lo, H.-Y. Hsu, C.-Y. Lin, E. W.-G. Diau, Chem. Commun.
2011, 47, 8910–8912; c) A. Yella, H.-W. Lee, H. N. Tsao, C. Yi,
A. K. Chiran, Md. K. Nazeeruddin, E. W.-G. Diau, C.-Y. Yeh, S. M.
Zakeeruddin, M. Grꢃtzel, Science 2011, 334, 629–634; d) H. Ima-
hori, T. Umeyama, S. Ito, Acc. Chem. Res. 2009, 42, 1809–1818;
e) R. B. Ambre, G.-F. Chang, M. R. Zanwar, C.-F. Yao, E. W.-G.
Diau, C.-H. Hung, Chem. Asian J. 2013, 8, 2144–2153.
[4] a) M. Liang, J. Chen, Chem. Soc. Rev. 2013, 42, 3453–3488; b) Y.-S.
Yen, C.-T. Lee, C.-Y. Hsu, H.-H. Chou, Y.-C. Chen, J. T. Lin, Chem.
Asian J. 2013, 8, 809–816; c) G. Zhang, H. Bala, Y. Cheng, D. Shi,
X. Lv, Q. Yu, P. Wang, Chem. Commun. 2009, 2198–2200; d) T. Su-
dyoadsuk, S. Pansay, S. Morada, R. Rattanawan, S. Namuangruk, T.
Keawin, S. Jungsuttiwong, V. Promarak, Eur. J. Org. Chem. 2013,
5051–5063; e) W.-I. Hung, Y.-Y. Liao, C.-Y. Hsu, H.-H. Chou, T.-H.
Lee, W.-S. Kao, J. T. Lin, Chem. Asian J. 2014, 9, 357–366;
f) K. R. J. Thomas, N. Kapoor, C.-P. Lee, K.-C. Ho, Chem. Asian J.
2012, 7, 738–750.
[5] Y. Ooyama, Y. Harima, Eur. J. Org. Chem. 2009, 2903–2934.
[6] a) S. Rai, M. Ravikan, Tetrahedron 2007, 63, 2455–2465; b) 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, J. Mater. Chem. A 2014, 2, 991–999;
c) M. J. Griffith, A. J. Mozer, Porphyrin Based Dye Sensitized Solar
Cells, Solar Cells-Dye-Sensitized Devices (Ed.: L. A. Kosyachenko),
2011, InTech, Available from: http://www.intechopen.com/books/
solar-cells-dye-sensitized-devices/porphyrin-based-dye-sensitized-so-
larcells.
[7] S. Mathew, A. Yella, P. Gao, R. Humphry-Baker, B. F. E. Curchod,
N. Ashari-Astani, I. Tavernelli, U. Rothlisberger, Md. K. Nazeerud-
din, M. Grꢃtzel, Nat. Chem. 2014, 6, 242–247.
[8] a) N. J. Jeon, H. G. Lee, Y. C. Kim, J. Seo, J. H. Noh, J. Lee, S. I.
Seok, J. Am. Chem. Soc. 2014, 136, 7837–7840; b) P. Qin, S. Paek,
M. I. Dar, N. Pellet, J. Ko, M. Grꢃtzel, M. K. Nazeeruddin, J. Am.
Chem. Soc. 2014, 136, 8516–8519.
[9] W. M. Campbell, A. K. Burrell, D. L. Officer, K. W. Jolley, Coord.
Chem. Rev. 2004, 248, 1363–1379.
[10] a) J. Rochford, D. Chu, A. Hagfeldt, E. Galoppini, J. Am. Chem.
Soc. 2007, 129, 4655–4665; b) M. Gervaldo, F. Fungo, E. N. Duranti-
ni, J. J. Silber, L. Sereno, L. Otero, J. Phys. Chem. B 2005, 109,
20953–20962; c) K. D. Seo, M. J. Lee, H. M. Song, H. S. Kang, H. K.
Kim, Dyes Pigm. 2012, 94, 143–149; d) N. R. de Tacconi, W. Chan-
manee, K. Rajeshwar, J. Rochford, E. Galoppini, J. Phys. Chem. C
2009, 113, 2996–3006; e) R. Ambre, K. B. Chen, C.-F. Yao, L. Luo,
E. W.-G. Diau, C.-H. Hung, J. Phys. Chem. C 2012, 116, 11907–
11916.
[11] a) A. J. Mozer, P. Wagner, D. L. Officer, G. G. Wallace, W. M.
Campbell, M. Miyashita, K. Sunahara, S. Mori, Chem. Commun.
11
&
&
Chem. Asian J. 2014, 00, 0 – 0
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
These are not the final page numbers! ÞÞ

www.chemasianj.org
Vinich Promarak et al.
2008, 4741–4743; b) J. K. Park, H. R. Lee, J. Chen, H. Shinokubo,
A. Osuka, D. Kim, J. Phys. Chem. C 2008, 112, 16691–16699;
c) A. W. I. Stephenson, P. Wagner, A. C. Partridge, K. W. Jolley,
V. V. Filichev, D. L. Officer, Tetrahedron Lett. 2008, 49, 5632–5635;
d) W. Zhou, B. Zhao, P. Shen, S. Jiang, H. Huang, L. Deng, S. Tan,
Dyes Pigm. 2011, 91, 404–412; e) W. Zhou, Z. Cao, S. Jiang, H.
Huang, L. Deng, Y. Liu, P. Shen, B. Zhao, S. Tan, X. Zhang, Org.
Electron. 2012, 13, 560–569; f) H.-Y. Hsu, H.-C. Chiang, J.-Y. Hu,
K. Awasthi, C.-L. Mai, C.-Y. Yeh, N. Ohta, E. W.-G. Diau, J. Phys.
Chem. C 2013, 117, 24761–24766.
[26] Gaussian 09, Revision A.1, M. J. Frisch, G. W. Trucks, H. B. Schlegel,
G. E. Scuseria, M. A. Robb, J. R. Cheeseman, G. Scalmani, V.
Barone, B. Mennucci, G. A. Petersson, H. Nakatsuji, M. Caricato, X.
Li, H. P. Hratchian, A. F. Izmaylov, J. Bloino, G. Zheng, J. L. Son-
nenberg, M. Hada, M. Ehara, K. Toyota, R. Fukuda, J. Hasegawa,
M. Ishida, T. Nakajima, Y. Honda, O. Kitao, H. Nakai, T. Vreven,
J. A. Montgomery, J. E. Peralta, F. Ogliaro, M. Bearpark, J. J. Heyd,
E. Brothers, K. N. Kudin, V. N. Staroverov, R. Kobayashi, J. Norm„
K. Raghavachari, A. Rendell, J. C. Burant, S. S. Iyengar, J. Tomasi,
M. Cossi, N. Rega, J. M. Millam, M. Klene, J. E. Knox, J. B. Cross,
V. Bakken, C. Adamo, J. Jaramillo, R. Gomperts, R. E. Stratmann,
O. Yazyev, A. J. Austin, R. Cammi, C. Pomelli, J. W. Ochterski,
R. L. Martin, K. Morokuma, V. G. Zakrzewski, G. A. Voth, P. Salva-
dor, J. J. Dannenberg, S. Dapprich, A. D. Daniels, Farkas, J. B. Fores-
man, J. V. Ortiz, J. Cioslowski, D. J. Fox, Gaussian, Inc., Wallingford,
CT, 2009.
[27] a) G. Marotta, M. A. Reddy, S. P. Singh, A. Islam, L. Han, F. D. An-
gelis, M. Pastore, M. Chrasekharam, ACS Appl. Mater. Interfaces
2013, 5, 9635–9647; b) S. Karthikeyan, J. Y. Lee, J. Phys. Chem. A
2013, 117, 10973–10979; c) S. Jungsuttiwong, R. Tarsang, T. Su-
dyoadsuk, V. Promarak, P. Khongpracha, S. Namuangruk, Org. Elec-
tron. 2013, 14, 711–722.
[28] a) C. Y. Lee, C. She, N. C. Jeong, J. T. Hupp, Chem. Commun. 2010,
46, 6090–6092; b) C. I. Oprea, P. Panait, F. Cimpoesu, M. Ferbintea-
nu, M. A. Gꢅrt¸u, Materials 2013, 6, 2372–2392.
[12] S. Eu, S. Hayashi, T. Umeyama, Y. Matano, Y. Araki, H. Imahori, J.
Phys. Chem. C 2008, 112, 4396–4405.
[13] a) J. K. Park, J. Chen, H. R. Lee, S. W. Park, H. Shinokubo, A.
Osuka, D. Kim, J. Phys. Chem. C 2009, 113, 21956–21963; b) A. J.
Mozer, M. J. Griffith, G. Tsekouras, P. Wagner, G. G. Wallace, S.
Mori, K. Sunahara, M. Miyashita, J. C. Earles, K. C. Gordon, L. Du,
R. Katoh, A. Furube, D. L. Officer, J. Am. Chem. Soc. 2009, 131,
15621–15623; c) K. Sunahara, M. J. Griffith, T. Uchiyama, P.
Wagner, D. L. Officer, G. G. Wallace, A. J. Mozer, S. Mori, ACS
Appl. Mater. Interfaces 2013, 5, 10824–10829.
[14] a) X.-F. Wang, O. Kitao, H. Zhou, H. Tamiaki, S. Sasaki, J. Phys.
Chem. C 2009, 113, 7954–7961; b) X.-F. Wang, O. Kitao, H. Zhou,
H. Tamiaki, S. Sasaki, Chem. Commun. 2009, 1523–1525; c) X.-F.
Wang, Y. Koyama, H. Nagae, Y. Wada, S. Sasaki, H. Tamiaki, J.
Phys. Chem. C 2008, 112, 4418–4426.
[15] a) W. M. Campbell, K. W. Jolley, P. Wagner, K. Wagner, P. J. Walsh,
K. C. Gordon, L. Schmidt-Mende, M. K. Nazeeruddin, Q. Wang, M.
Grꢃtzel, D. L. Officer, J. Phys. Chem. C 2007, 111, 11760–11762;
b) R. A. Jensen, H. V. Ryswyk, C. She, J. M. Szarko, L. X. Chen,
J. T. Hupp, Langmuir 2010, 26, 1401–1404; c) M. Ishida, S. W. Park,
D. Hwang, Y. B. Koo, J. L. Sessler, D. Y. Kim, D. Kim, J. Phys.
Chem. C 2011, 115, 19343–19354.
[16] a) C.-Y. Lin, C.-F. Lo, L. Luo, H.-P. Lu, C.-S. Hung, E. W.-G. Diau,
J. Phys. Chem. C 2009, 113, 755–764; b) C.-W. Chang, L. Luo, C.-K.
Chou, C.-F. Lo, C.-Y. Lin, C.-S. Hung, Y.-P. Lee, E. W.-G. Diau, J.
Phys. Chem. C 2009, 113, 11524–11531; c) C.-F. Lo, S.-J. Hsu, C.-L.
Wang, Y.-H. Cheng, H.-P. Lu, E. W.-G. Diau, C.-Y. Lin, J. Phys.
Chem. C 2010, 114, 12018–12023.
[29] B. Delley, J. Chem. Phys. 2000, 113, 7756–7764.
[30] a) S. Namuangruk, R. Fukuda, M. Ehara, J. Meeprasert, T. Khanasa,
S. Morada, T. Kaewin, S. Jungsuttiwong, T. Sudyoadsuk, V. Promar-
ak, J. Phys. Chem. C 2012, 116, 25653–25663; b) S. Namuangruk, K.
Sirithip, R. Rattanawan, T. Keawin, T. Sudyoadsuk, V. Promarak, N.
Kungwan, S. Jungsuttiwong, Dalton Trans. 2014, 43, 9166–9176;
c) R. Tarsang, V. Promarak, T. Sudyoadsuk, S. Namuangruk, S. Jung-
suttiwong, J. Photochem. Photobiol. A 2014, 273, 8–16; d) S. Jung-
suttiwong, T. Yakhanthip, Y. Surakhot, J. Khunchalee, T. Sudyoad-
suk, V. Promarak, N. Kungwan, S. Namuangruk, J. Comput. Chem.
2012, 33, 1517–1523.
[31] a) N. Koumura, Z.-S. Wang, S. Mori, M. Miyashita, E. Suzuki, K.
Hara, J. Am. Chem. Soc. 2006, 128, 14256–14257; b) D. Kim, M.-S.
Kang, K. Song, S. O. Kang, J. Ko, Tetrahedron 2008, 64, 10417–
10422; c) Z.-S. Wang, N. Koumura, Y. Cui, M. Takahashi, H. Sekigu-
chi, A. Mori, T. Kubo, A. Furube, K. Hara, Chem. Mater. 2008, 20,
3993–4003; d) J. Liu, R. Li, X. Si, D. Zhou, Y. Shi, Y. Wang, X.
Jing, P. Wang, Energy Environ. Sci. 2010, 3, 1924–1928.
[17] a) T. Bessho, S. M. Zakeeruddin, C.-Y. Yeh, E. W.-G. Diau, M. Grꢃt-
zel, Angew. Chem. Int. Ed. 2010, 49, 6646–6649; Angew. Chem.
2010, 122, 6796–6799; b) H. Imahori, Y. Matsubara, H. Iijima, T.
Umeyama, Y. Matano, S. Ito, M. Niemi, N. V. Tkachenko, H. Lem-
metyinen, J. Phys. Chem. C 2010, 114, 10656–10665.
[18] G. Di Carlo, A. O. Biroli, F. Tessore, M. Pizzotti, P. R. Mussini, A.
Amat, F. D. Angelis, A. Abbotto, V. Trifiletti, R. Ruffo, J. Phys.
Chem. C 2014, 118, 7307–7320.
[32] M. K. Nazeeruddin, F. D. Angelis, S. Fantacci, A. Selloni, G. Viscar-
di, P. Liska, S. Ito, B. Takeru, M. Grꢃtzel, J. Am. Chem. Soc. 2005,
127, 16835–18647.
[19] C. Y. Lin, Y.-C. Wang, S.-J. Hsu, C.-F. Lo, E. W.-G. Diau, J. Phys.
Chem. C 2010, 114, 687–693.
[33] a) L. Luo, C.-J. Lin, C.-Y. Tsai, H.-P. Wu, L.-L. Li, C.-F. Lo, C.-Y.
Lin, E. W.-G. Diau, Phys. Chem. Chem. Phys. 2010, 12, 1064–1071;
b) M. Pastore, F. D. Angelis, J. Phys. Chem. Lett. 2013, 4, 956–974;
c) R. Scholin, M. Quintana, E. M. J. Johansson, M. Hahlin, T. Mari-
nado, A. Hagfeldt, H. Rensmo, J. Phys. Chem. C 2011, 115, 19274–
19279.
[20] a) K. Hara, M. Kurashige, Y. Dan-oh, C. Kasada, A. Shinpo, S.
Suga, K. Sayama, H. Arakawa, New J. Chem. 2003, 27, 783–785;
b) P. Thongkasee, A. Thangthong, N. Janthasing, T. Sudyoadsuk, S.
Namuangruk, T. Keawin, S. Jungsuttiwong, V. Promarak, ACS Appl.
Mater. Interfaces 2014, 6, 8212–8222.
[34] a) Z.-S. Wang, Y. Cui, Y. Dan-oh, C. Kasada, A. Shinpo, K. Hara, J.
[21] V. Promarak, P. L. Burn, J. Chem. Soc. Perkin Trans. 1 2001, 14–20.
[22] a) S. M. LeCours, S. G. DiMagno, M. J. Therien, J. Am. Chem. Soc.
1996, 118, 11854–11864; b) S. M. LeCours, H. W. Guan, S. G. Di-
Magno, C. H. Wang, M. J. Therien, J. Am. Chem. Soc. 1996, 118,
1497–1503; c) S. M. LeCours, C. M. Philips, J. C. D. Paula, M. J.
Therien, J. Am. Chem. Soc. 1997, 119, 12578–12589.
[23] T. Khanasa, N. Jantasing, S. Morada, N. Leesakul, R. Tarsang, S. Na-
muangruk, T. Keawin, S. Jungsuttiwong, T. Sudyoadsuk, V. Promar-
ak, Eur. J. Org. Chem. 2013, 2608–2620.
Phys. Chem. C 2007, 111, 7224–7230; b) T. W. Hamann, R. A.
Jensen, A. B. F. Martinson, H. V. Ryswyk, J. T. Hupp, Energy Envi-
ron. Sci. 2008, 1, 66–78; c) Q. Wang, W. M. Campbell, E. E. Bonfan-
tani, K. W. Jolley, D. L. Officer, P. J. Walsh, K. Gordon, R. Humph-
ry-Baker, M. K. Nazeeruddin, M. Grꢃtzel, J. Phys. Chem. B 2005,
109, 15397–15409; d) C.-W. Lee, H.-P. Lu, C.-M. Lan, Y.-L. Huang,
Y.-R. Liang, W.-N. Yen, Y.-C. Liu, Y.-S. Lin, E. W.-G. Diau, C.-Y.
Yeh, Chem. Eur. J. 2009, 15, 1403–1412.
[35] a) S. Mathew, H. Iijima, Y. Toude, T. Umeyama, Y. Matano, S. Ito,
N. V. Tkachenko, H. Lemmetyinen, H. Imahori, J. Phys. Chem. C
2011, 115, 14415–14424; b) L. Jing, W. Wenjun, Y. Jiabao, T. Jin, L.
Yitao, H. Jianli, Sci. China Chem. 2011, 54, 699–706.
[24] S. Haid, M. Marszalek, A. Mishra, M. Wielopolski, J. Teuscher, J.-E.
Moser, R. Humphry-Baker, S. M. Zakeeruddin, M. Grꢃtzel, P.
Bꢃuerle, Adv. Funct. Mater. 2012, 22, 1291–1302.
[25] a) H. Choi, C. Baik, S. O. Kang, J. Ko, M.-S. Kang, M. K. Nazeerud-
din, M. Grꢃtzel, Angew. Chem. Int. Ed. 2008, 47, 327–330; Angew.
Chem. 2008, 120, 333–336; b) M.-S. Tsai, Y.-C. Hsu, J. T. Lin, H.-C.
Chen, C.-P. Hsu, J. Phys. Chem. C 2007, 111, 18785–18793.
[36] H.-P. Lu, C.-Y. Tsai, W.-N. Yen, C.-P. Hsieh, C.-W. Lee, C.-Y. Yeh,
E. W.-G. Diau, J. Phys. Chem. C 2009, 113, 20990–20997.
[37] X.-H. Zhang, Y. Cui, R. Katoh, N. Koumura, K. Hara, J. Phys.
Chem. C 2010, 114, 18283–18290.
&
&
12
Chem. Asian J. 2014, 00, 0 – 0
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ÝÝ These are not the final page numbers!

www.chemasianj.org
Vinich Promarak et al.
[38] P. Shen, X. Liu, S. Jiang, L. Wang, L. Yi, D. Ye, B. Zhao, S. Tan,
Dyes Pigm. 2012, 92, 1042–1051.
[41] N. Koide, L. Han, Rev. Sci. Instrum. 2004, 75, 2828–2831.
[42] S. Ito, H. Matsui, K. Okada, S. Kusano, T. Kitamura, Y. Wada, S. Ya-
[39] J. Van de Lagemaat, N.-G. Park, A. J. Frank, J. Phys. Chem. B 2000,
104, 2044–2052.
nagida, Sol. Energy Mater. Sol. Cells 2004, 82, 421–429.
[40] D. P. Hagberg, J.-H. Yum, H. Lee, F. De Angelis, T. Marinado, K. M.
Karlsson, R. Humphry-Baker, L. Sun, A. Hagfeldt, M. Grꢃtzel,
M. K. Nazeeruddin, J. Am. Chem. Soc. 2008, 130, 6259–6266.
Received: July 2, 2014
Published online: && &&, 0000
13
&
&
Chem. Asian J. 2014, 00, 0 – 0
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
These are not the final page numbers! ÞÞ

FULL PAPER
Solar Cells
To dye for: A series of new zinc–por-
phyrin dyes that contain different
meso substituents (phenyl, carbazole
phenyl, and carbazole thiophenyl
groups) and bithiophenyl cyanoacrylic
acid as the p-conjugated anchoring
moiety were designed, synthesized,
and characterized as sensitizers for
dye-sensitized solar cells (see scheme).
Kanokkorn Sirithip,
Narid Prachumrak,
Rattanawalee Rattanawan,
Tinnagon Keawin,
Taweesak Sudyoadsuk,
Supawadee Namuangruk,
iporn Jungsuttiwong,
Vinich Promarak*
&&&& — &&&&
Zinc–Porphyrin Dyes with Different
meso-Aryl Substituents for Dye-Sensi-
tized Solar Cells: Experimental and
Theoretical Studies
&
&
14
Chem. Asian J. 2014, 00, 0 – 0
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ÝÝ These are not the final page numbers!