Regulation of dithiafulvene-based molecular shape and aggregation on TiO2 for high efficiency dye-sensitized solar cells

Article abstract of DOI:10.1039/c8tc06109b

A well-matched relationship between the molecular shape and aggregation of donor-π-acceptor (D-π-A) organic dyes is of great significance for realizing the principle of maximizing the performance of dye-sensitized solar cells (DSCs). To this end, two dithiafulvene-based organic sensitizers with different molecular shapes were synthesized, and the influence of their aggregation on TiO₂ on the various performance parameters of DSCs was investigated. It was found that V-shaped DTF-C5, with a larger flare angle of 150.6° between the donor and acceptor units in the molecular structure, tended to form compact aggregates on the surface of TiO₂ without the loss of adsorbed dyes, thus giving a higher short-circuit density (J_sc) of 14.92 mA cm^?2 and a power conversion efficiency (PCE) of 7.39%; these values were 1.48 and 1.53 times higher than those of a DSC with a CDCA co-adsorbent, respectively. On the other hand, DTF-C6, possessing a typical V-shaped conformation with a flare angle of 120.6°, needed to co-adsorb with CDCA to fill the vacant sites between the dye aggregates on the TiO₂ surface, with the aim of reducing current loss and suppressing electron recombination. Compared to a DSC with pristine DTF-C6 aggregation, an example based on the co-adsorbed system dramatically raised the PCE from 5.50% to 9.04%, owing to the improved J_sc and open-circuit voltage values. This work presents a perspective for the rational regulation of molecular shapes and the dye aggregation of organic dyes for highly efficient DSCs.

Full text of DOI:10.1039/c8tc06109b

View Article Online
View Journal
Journal of
Materials Chemistry C
Accepted Manuscript
This article can be cited before page numbers have been issued, to do this please use: Y. Wu, Q. Zhang,
J. Li, X. Tian, D. Li, X. Lu, B. Xu, Y. Wu and K. Guo, J. Mater. Chem. C, 2019, DOI: 10.1039/C8TC06109B.
This is an Accepted Manuscript, which has been through the
Volume
4 Number 1 7 January 2016 Pages 1–224
Royal Society of Chemistry peer review process and has been
accepted for publication.
Journal of
Materials Chemistry C
Accepted Manuscripts are published online shortly after
Materials for optical, magnetic and electronic devices
www.rsc.org/MaterialsC
acceptance, before technical editing, formatting and proof reading.
Using this free service, authors can make their results available
to the community, in citable form, before we publish the edited
article. We will replace this Accepted Manuscript with the edited
and formatted Advance Article as soon as it is available.
You can find more information about Accepted Manuscripts in the
author guidelines.
Please note that technical editing may introduce minor changes
to the text and/or graphics, which may alter content. The journal’s
standard Terms & Conditions and the ethical guidelines, outlined
in our author and reviewer resource centre, still apply. In no
event shall the Royal Society of Chemistry be held responsible
for any errors or omissions in this Accepted Manuscript or any
consequences arising from the use of any information it contains.
ISSN 2050-7526
PAPER
~
Nguyên T. K. Thanh, Xiaodi Su et al.
Fine-tuning of gold nanorod dimensions and plasmonic properties using
the Hofmeister effects
rsc.li/materials-c

Please do not adjust margins
Journal of Materials Chemistry C
Page 1 of 9
View Article Online
DOI: 10.1039/C8TC06109B
Journal Name
ARTICLE
Regulation of dithiafulvene-based molecular shape and their
aggregations on TiO2 for high efficiency dye-sensitized solar cells
Yuezhen Wu,a Quande Zhang,b Jie Li,a Xia Tian,a Da Li,a Xiaoqing Lu,b Bingshe Xu,a Yucheng Wu,a
Received 00th January 20xx,
Accepted 00th January 20xx
Kunpeng Guo*a
DOI: 10.1039/x0xx00000x
A well-matched relationship between the molecular shape and the aggregations of donor-π-acceptor (D-π-A) organic dyes
is of great significance for understanding the principle of maximizing the performance of dye-sensitized solar cells (DSCs).
To this end, two dithiafulvene-based organic sensitizers with different molecular shapes were synthesized, and the influence
of their aggregations formed on TiO2 on the diversity performance of DSCs were investigated. It was found that V-shaped
DTF-C5 with a larger flare angle of 150.6o between the donor and acceptor unit in molecular sturcture tend to form compact
aggregates on the surface of TiO2 without the loss of adsorbed dyes, thus giving a higher short-circuit density (Jsc) of 14.92
mA cm-2 and a power conversion efficiency (PCE) of 7.39%, which were 1.48-fold and 1.53-fold higher than those of the DSC
with CDCA co-adsorbent, respectively. On the other hand, DTF-C6 possessing a typical V-shaped conformation with a flare
angle of 120.6o needed to co-adsorb with CDCA to fill up the vacant sites between the dye aggregates on the TiO2 surface,
aiming to reduce the current loss and suppress the electron recombination. Compared to the DSC with pristine DTF-C6
aggregation, that based on the co-adsorbed system dramatically uplifted the PCE from 5.50% to 9.04%, owing to the
improved Jsc and open-circuit voltage. This work presents a perspective of rational regulation on molecular shapes and dye
aggregations of organic dyes for highly efficient DSCs.
www.rsc.org/
was realized in Wang’s group.17 Through collaborative
sensitization by a carbazole and a triphenylamine based D-π-A
dyes, a recorded PCE of 14.3% was realized in Yano and
Hanaya’s group.18 In addition to the mostly used arylamine
derivatives sensitizing dyes, our group also found dithiafulvene
based D-π-A dyes could be effective sensitizers for high-
performance DSCs, owing to their excellent electron-donative
characteristic and more concise synthesis.19-23
To date, studies have found there are two primary means for
realizing high PCE in DSCs, one is enhancing the short-circuit
density (Jsc) and the other is improving the open-circuit voltage
(Voc).24-29 In principle, the Jsc can be enhanced by broaden the
absorption spectra of dyes via strengthening the intramolecular
charge transfer (ICT) effect with suitable molecular
engineering.30-33 Thereby, various enlarged conjugation of D-π-
A organic dyes with different shapes have been studied.
However, larger conjugated frameworks are susceptible to dye-
aggregation after absorbing on the surface of TiO2, and may
lead to vacant sites between the dye aggregates. In this case,
Voc would be decreased due to the adverse electron
recombination, and even current loss was found due to the
limited charge transfer and injection.34-38 To tackle this issue,
researchers resorted to introduce coadsorbents, e.g.,
chenodeoxycholic acid (CDCA),39-41 onto the vacant sites of TiO2
surface, or design organic dyes with large steric hindrance (e.g.
star-shaped dyes).42-45 However, some organic dyes with
reduced steric hindrance, which are more prone to form
aggregates, were also
Introduction
Converting solar energy into electricity through photovoltaic
(PV) technologies has attracted huge attention to tackle the
issues of environmental pollution and the shortage of fossil
fuels supply.1-3 Among the emerging PV technologies, dye-
sensitized solar cells (DSCs) show fascinating prospects due to
their advanced features, such as handy device fabrication,
environmental friendliness, low production cost and fascinating
performance under indoor conditions with low-intensity light.4-7
To improve the performance of DSCs, enormous efforts in
sensitizing dyes innovation and devices engineering have been
made by the worldwide researches.8-12 Recently, donor-π-
acceptor (D-π-A)-type organic dyes have exhibited merits to
promote the performance of DSCs, including flexibility in
molecular designing, high molar extinction coefficient and
favourable charge injection from dyes to photonanode.13-16 For
example, employing N-annulated perylene as donative building
blocks for DSCs, a power conversion efficiency (PCE) over 12%
a. Ministry of Education Key Laboratory of Interface Science and Engineering in
Advanced Materials, Research Center of Advanced Materials Science and
Technology, Taiyuan University of Technology, Taiyuan 030024, China.
mail: guokunpeng@tyut.edu.cn
*E-
b. School of Materials Science and Engineering, China University of Petroleum,
Qingdao, Shandong 266580, China
Electronic Supplementary Information (ESI) available: 1H NMR. See DOI:
10.1039/x0xx00000x
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 1
Please do not adjust margins

Please do not adjust margins
Journal of Materials Chemistry C
Page 2 of 9
ARTICLE
Journal Name
S
C8H17
C8H17
CN
COOH
UV-Vis absorption spectra of the dye in solution and loading on
TiO2 films were measured with a HITIACH U-3900 spectrometer
S
View Article Online
DOI: 10.1039/C8TC06109B
S
S
S
at room temperature. Photoluminescent (PL) spectra were
recorded in a Horiba Fluoromax 4 spectrometer in diluted THF
solution (1×10-5 M). Cyclic voltammetry (CV) curve of dye was
recorded on a CHI600E Electrochemical Analyzer at a scan rate
of 0.1V s-1. The oxidation potential of the sensitizer was
C8H17
C8H17
S
DTF-C5
CN
COOH
S
S
S
O
measured
in
DMF
with
tetra-n-butylammonium
N
hexafluorophosphate (TBAPF6) (0.1 M) as the electrolyte, glassy
carbon as the working electrode, Ag/Ag+ as the reference
electrode, and Pt as the counter electrode. The potential of the
reference electrode was calibrated with Fc/Fc+ as an internal
C4H9
DTF-C6
Fig. 1 Chemical structures of dyes DTF-C5 and DTF-C6.
reported yielding high efficiencies in DSCs without using reference and converted to normal hydrogen electrode (NHE)
coadsorbents.46,47 These results indicate molecular shapes and by addition of 630 mV.
aggregations of organic dyes exert great influence on DSCs’ DSCs fabrication and photovoltaic measurements
performance. However, systematic studies on the relationship
The preparation of DSCs photoanode and electrolyte was
between molecular conformations and dye aggregations in one
followed the previous literature.12 In cell assembly, for the non-
dye system to maximize the performance of DSCs remain
coadsorbent devices, DTF-C5 and DTF-C6 were loaded onto the
TiO2 (~ 12 μm thick) films by immersion into their
tetrahydrofuran (THF) solutions (0.2 mM dye) without the use
of CDCA for 24 h at room temperature, respectively. For the
relatively rare.
In this research, two D-π-A dithiafulvene-based organic
sensitizers with the same electron donor and acceptor units but
differing in the flare angles induced by the π-bridges were
coadsorbent based devices, DTF-C5 and DTF-C6 were loaded
designed and synthesized (Fig. 1), respectively. DTF-C5 with
onto the TiO2 (~ 12 μm thick) film by immersion into their THF
solutions (0.5 mM dye) with CDCA (10 mM) for 24 h at room
temperature, respectively. Before drying under vacuum, the
phenyl-thiophene-phenyl π-bridge and DTF-C6 with phenyl-
phenoxazine-phenyl π-bridge showed similar absorption
spectra in solution, which were beneficial to evaluate the effect
films were rinsed with acetonitrile to remove the unabsorbed
of molecular shapes and dye aggregations on the DSCs’
sensitizers multiple times until the solution became clear. Then,
performance. The influence of their CDCA- co-adsorption-
the films were assembled into a solar cell together with a Pt–
dependent aggregations on TiO2 surface on the performance of
sputtered FTO counter electrode and acetonitrile / valeronitrile
DSCs was investigated. The DSC fabricated with pristine DTF-C5
(85:15, volume ratio) electrolyte containing 0.6 M 1, 2–
displayed a far higher PCE of 7.39% than that with CDCA co-
dimethyl–3–propylimi dazolium iodide, 0.03 M I2, 0.1 M
adsorbent due to the compact arrangement of the sensitizers.
guanidinium thiocyanate, and 0.5 M 4–tert-butylpyridine. The
Interestingly, for the typical V-shaped molecule with a reduced
active area of the photoanode film for the DSC performance test
flare angle, DTF-C6 based DSCs achieved a dramatically
was typically 0.25 cm–2.
The photocurrent density-voltage (J-V) characteristics curves
were measured by the Newport PVIV-3A system. The light
increased PCE of 9.04% with the co-adsorption of CDCA to cover
the vacant sites between the dye aggregates on the TiO2 surface.
source (Oriel solar simulator, 450 W Xe lamp, AM 1.5 global
filter) was calibrated to 1 sun (100 mW cm-2). Incident Photon
to Current Efficiency (IPCE) was measured at varying
Experimental section
Materials and reagents
wavelengths (350-750 nm) with an interval of 5 nm. Nyquist
spectroscopy was measured on the electrochemical
workstation (Zahner, Zennium) with a frequency response
analyzer under an intensity modulated (5-70W m-2) light
emitting diode (525 nm) driven by a Zahner (PP211) source
supply. The frequency range was set from 100 KHz to 0.1 Hz.
Synthetic procedures
All solvents and reagents, unless otherwise stated, were of
purist quality and used as received. Phenoxazine, 1-
bromobutane,
(triphenylphosphine)
4-formylphenylboronic
palladium (0)
acid,
(Pd(PPh3)4),
tetrakis
N-
bromosuccinimide, 2,5-dibromothiophene, and 2-cyanoacetic
acid were purchased from Energy Chemical Ltd. FTO conductive
glasses (sheet resistance of 15 Ω/sq, Nippon Sheet Glass) were
used.
ODT, C1, A and B were obtained as depicted in the previous
literature.19, 48-50
Characterization
4,5-bis(octylthio)-1,3-dithiole-2-thione (ODT)
NMR spectra (1H and 13C) measurements were carried out at a
Bruker 600 spectrometer in 600 MHz for 1H NMR and 151 MHz
for 13C NMR, respectively, using d-chloroform or d-DMSO as the
solvent. Data was listed in parts per million (ppm) on the delta
scale (δ) and coupling constants were reported in Hz. The
splitting patterns were designated as follows: s (singlet); d
(doublet); t (triplet); q (quartet); m (multiplet) and br (broad).
1-Bromooctane (6.8 g, 35.0 mmol) and [Et4N]2[Zn(DMIT)2]
(5.0 g, 7.0 mmol) were dissolved in CH3CN (100 mL). Then the
reaction mixture was stirred at 80°C for 2 h. After cooling to
room temperature, the combined organic extracts were dried
over anhydrous MgSO4, filtered, and concentrated under
reduced pressure. Compound ODT was obtained as yellowish oil
by silicon gel column chromatography with petroleum ether as
2 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Page 3 of 9
Journal of Materials Chemistry C
Please do not adjust margins
Journal Name
ARTICLE
the eluent (2.7 g, yield 90%). 1H NMR (600 MHz, CDCl3) δ= 2.93– obtain D2 as yellow solid (460.0 mg, yield 28%).1VHiewNAMrticRle O(6nl0in0e
DOI: 10.1039/C8TC06109B
2.81 (m, 3H); 1.66 (dt, J= 15.0, 7.4 Hz, 3H); 1.41 (dt, J= 14.7, 7.3 MHz, CDCl3) δ = 9.98 (s, 1H); 7.86 (d, J = 7.6 Hz, 2H); 7.64 (d, J =
Hz, 4H); 1.34–1.22 (m, 16H); 0.88 (t, J= 7.0 Hz, 6H).13C-NMR (151 7.9 Hz, 2H); 7.49 (d, J = 8.4 Hz, 2H); 7.22 (d, J = 8.4 Hz, 2H); 7.07
MHz, CDCl3) δ= 213.49; 139.00; 39.67; 35.83; 34.72; 32.64; (dd, J = 25.1, 9.0 Hz, 2H); 6.91 (d, J = 20.1 Hz, 2H); 6.51 (d, J = 8.2
32.05; 31.70; 31.47; 31.15; 25.57; 16.98. MALDI-TOF: m/z [M]+ Hz, 2H); 6.44 (s, 1H), 3.49 (s, 2H); 2.82 (dd, J = 8.2, 6.6 Hz, 4H);
cacld. C19H34S5, 422.7838; found: 422.7836.
4,4'-(10-butyl-10H-phenoxazine-3,7-diyl)dibenzaldehyde (C2)
1.64 (d, J = 7.1 Hz, 5H); 1.48–1.24 (m, 24H); 1.02 (t, J = 7.4 Hz,
3H); 0.87 (q, J = 7.1 Hz, 6H). 13C-NMR (151 MHz, CDCl3) δ
Under a nitrogen atmosphere, 4-formylphenylboronic acid =194.46; 148.65; 148.10; 147.90; 139.79; 137.90; 137.64;
(2.7 g, 22.0 mmol), B (4.0 g, 10.0 mmol), Pd(PPh3)4 (0.6 g, 0.5 136.46; 135.08; 134.76; 133.19; 130.58; 130.09; 129.15; 128.89;
mmol), K2CO3 (6.9 g, 50 mmol) and 1,2-glycol dimethyl ether 127.62; 125.48; 124.70; 116.82; 116.45; 114.67; 114.48; 46.78;
(DME) (100 mL) were added into a 250 mL three-necked flask. 39.04; 34.73; 32.71; 32.07; 31.51; 30.20; 25.56; 23.10; 17.00;
The mixture was stirred at 90°C for 12 h. After cooling to room 16.82. MALDI-TOF: m/z [M]+ cacld. C49H59NO2S4, 821.3429;
temperature, the mixture was poured into H2O, extracted with found: 821.3426.
chloroform and dried over anhydrous MgSO4. After filtration (E)-3-(4-(5-(4-((4,5-bis(octylthio)-1,3-dithiol-2-
and concentration under reduced pressure, product C2 was ylidene)methyl)phenyl)thiophen-2-yl)phenyl)-2-cyanoacrylic
obtained as red solid powder using silica gel column acid (DTF-C5)
chromatography with petroleum ether:CH2Cl2 (2:1, v:v) as the
Under a nitrogen atmosphere, D1 (200.0 mg, 0.3 mmol),
eluent (2.33 g, 52%). 1H NMR (600 MHz, CDCl3) δ =10.02 (s, 2H); cyanoacetic acid (123.2 mg, 1.5 mmol) and piperidine (0.19 mL,
7.92–7.90 (m, 4H); 7.68–7.66 (m, 4H); 7.14 (dd, J = 8.3, 2.2 Hz, 1.9 mmol) were dissolved in CHCl3 (10 mL). The resulting
2H); 6.97 (d, J = 2.2 Hz, 2H); 6.59 (d, J = 8.4 Hz, 2H); 3.58–3.55 mixture was refluxed for 12 h. After cooling to room
(m, 2H); 1.71 (t, J = 7.9 Hz, 2H); 1.50 (dt, J = 14.8, 7.5 Hz, 2H); temperature, the solvents were removed under reduced
1.05 (t, J = 7.4 Hz, 3H). 13C-NMR (151 MHz, CDCl3) δ =194.53; pressure, and the residue was purified by silica gel column
148.57; 148.04; 137.73; 136.09; 135.26; 133.22; 129.26; 125.62; chromatography with CH2Cl2:CH3OH (10:1, v:v) as the eluent to
116.90; 114.71; 80.14; 79.93; 79.72; 46.81; 30.15; 23.08; 16.79. afford the dye DTF-C5 as orange yellow solid (132.1 mg, yield
MALDI-TOF: m/z [M]+ cacld. C30H25NO3, 447.1834; found: 60%). 1H NMR (600 MHz, DMSO) δ =7.89 (s, 1H); 7.87 (d, J = 4.5
447.1832.
Hz, 2H); 7.78 (d, J = 8.3 Hz, 2H); 7.64 (d, J = 8.4 Hz, 2H); 7.61 (d,
J = 3.8 Hz, 1H); 7.51 (d, J = 3.8 Hz, 1H); 7.19 (d, J = 8.5 Hz, 2H);
6.66 (s, 1H); 1.93–1.86 (m, 4H); 1.5–1.47 (m, 4H), 1.31–1.28 (m,
4-(5-(4-((4,5-bis(octylthio)-1,3-dithiol-2-
ylidene)methyl)phenyl)thiophen-2-yl)benzaldehyde (D1)
Under a nitrogen atmosphere, ODT (845.6 mg, 2 mmol) and 4H); 1.15 (d, J = 5.9 Hz, 17H); 0.76 (d, J = 3.6 Hz, 6H). 13C-NMR
C1 (730.0 mg, 2.5 mmol) were dissolved in boiling toluene (20 (151 MHz, THF) δ= 145.38; 143.11; 141.32; 135.04; 135.02;
mL), then P(OEt)3 (5 mL) was added. The resulting mixture was 132.07; 131.31; 130.25; 129.06; 127.12; 126.32; 125.53; 125.21;
refluxed for 3 h. After cooling and addition of dichloromethane, 125.02; 124.15; 123.27; 119.02; 113.87; 44.38; 36.73; 32.78;
the mixture was washed with brine and dried over anhydrous 30.85; 30.58; 30.11; 29.44; 28.25; 23.54; 20.86; 14.45; 14.25.
MgSO4. Solvents were removed under reduced pressure, and MALDI-TOF: m/z [M]+ cacld. C40H47NO2S5, 733.2210; found:
the residue was purified by silica gel column chromatography 733.2208.
with petroleum ether: acetic ether (20: 1, v:v) as the eluent to (E)-3-(4-(7-(4-((4,5-bis(octylthio)-1,3-dithiol-2-
obtain D1 as yellow solid (373.5 mg, yield 28%). 1H NMR (600 ylidene)methyl)phenyl)-10-butyl-10H-phenoxazin-3-yl)phenyl)-
MHz, CDCl3) δ =9.98 (s, 1H); 7.86 (d, J = 8.0 Hz, 2H); 7.74 (d, J = 2-cyanoacrylic acid (DTF-C6)
7.9 Hz, 2H); 7.60 (d, J = 8.1 Hz, 2H); 7.41 (d, J = 3.4 Hz, 1H); 7.30
Under a nitrogen atmosphere, D2 (246.0 mg, 0.3 mmol),
(d, J = 2.0 Hz, 1H); 7.22 (d, J = 7.8 Hz, 2H); 6.44 (s, 1H); 2.86–2.79 cyanoacetic acid (123.2 mg, 1.5 mmol) and piperidine (0.19
(m, 4H); 1.65 (dq, J = 14.7, 7.4 Hz, 4H); 1.46– 1.37 (m, 5H); 1.33– mL, 1.9 mmol) were dissolved in CHCl3 (10 mL). The resulting
1.25 (m, 17H); 0.88 (q, J = 7.1 Hz, 7H). 13C-NMR (151 MHz, CDCl3) mixture was refluxed for 12 h. After cooling to room
δ =194.12; 148.64; 144.38; 142.90; 139.04; 137.98; 136.40; temperature, the solvents were removed under reduced
133.87; 133.36; 130.77; 130.13; 129.05; 128.66; 128.52; 127.78; pressure, and the residue was purified by silica gel column
127.02; 116.41; 39.06; 34.69; 32.69; 32.02; 31.46; 25.52; 16.94. chromatography with CH2Cl2:CH3OH (10:1, v:v) as the eluent to
MALDI-TOF: m/z [M]+ cacld. C37H46OS5, 666.2152; found: afford the dye DTF-C6 as red solid (80.0 mg, yield 30 %). 1H
666.2149.
4-(7-(4-((4,5-bis(octylthio)-1,3-dithiol-2-ylidene)methyl)phenyl)- 7.75 (d, J = 8.2 Hz, 2H); 7.64 (d, J = 8.4 Hz, 2H); 7.24 (ddd, J =
10-butyl-10H-phenoxazin-3-yl)benzaldehyde (D2) 15.8, 10.3, 5.1 Hz, 4H); 7.05 (dd, J = 40.5, 1.8 Hz, 2H); 6.80 (t, J
NMR (600 MHz, DMSO) δ =7.98 (s, 1H); 7.93 (d, J = 7.7 Hz, 2H);
Under a nitrogen atmosphere, ODT (845.6 mg, 2 mmol) and = 8.7 Hz, 2H); 6.73 (s, 1H); 3.64 (d, J = 6.3 Hz, 2H); 2.89–2.84
C2 (1.1 g, 2.5 mmol) were dissolved in boiling toluene (20 mL), (m, 4H); 1.60–1.56 (m, 4H); 1.48–1.21 (m, 24H); 0.97 (t, J = 7.3
then P(OEt)3 (5 mL) was added. The resulting mixture was Hz, 3H); 0.84 (dt, J = 12.5, 4.9 Hz, 6H). 13C-NMR (151 MHz, THF)
refluxed for 3 h. After cooling and addition of dichloromethane,
δ
the mixture was washed with brine and dried over anhydrous =146.07; 143.66; 138.03; 135.91; 134.14; 133.95; 133.00;
MgSO4. Solvents were removed under reduced pressure, and 132.31; 132.02; 128.78; 128.07; 126.61; 125.73; 123.10; 30.89;
the residue was purified by silica gel column chromatography 30.72; 30.15; 29.47; 28.26; 23.55; 20.88; 14.46; 14.26. MALDI-
with petroleum ether: acetic ether (20: 1, v:v) as the eluent to TOF: m/z [M]+ cacld. C52H60N2O3S4, 888.3487; found: 888.3486.
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 3
Please do not adjust margins

Please do not adjust margins
Journal of Materials Chemistry C
Page 4 of 9
ARTICLE
Journal Name
S
S
S
S
C8H17
C8H17
S
LUMOs of the two sensitizers. As shown in Fig. 2b, the HOMO
electron density is mainly located at the dithiafulvenyl donor
View Article Online
DOI: 10.1039/C8TC06109B
Pd(PPh3) ,
4
ODT
S
+
(HO)2
B
CHO
CHO
Br
OHC
Br
S
K2CO3, H2O, (CH2OMe)2, N2, reflux
P(OEt)3, toluene, N2, reflux
C1
part, while the electron density of LUMO is transferred to the
cyanoarylic acid acceptor part. It has demonstrated that the
cyanoarylic acid is predominantly adsorbed onto the TiO2 by
forming a strong didentate bridging linkage with Brønsted acid
sites on the TiO2 surface. Therfore, upon photo-excition, the
HOMO-LUMO excitation can efficiently transfer electrons from
the donor part to the acceptor part anchored on TiO2, which is
desirable for the required charge separation in DSCs.
2-cyanoacetic acid, piperidine
CHO
S
S
CN
S
S
S
S
S
S
C8H17
C8H17
C8H17
C8H17
chloroform,
, refiux
COOH
N2
S
S
D1
DTF-C5
C4H9
C4H9
H
N
N
NBS
N
potassium tert-butoxide
N2
+
Br
Acetic acid, THF
O
Br
O
Br
THF,
O
B
A
C4H9
S
S
S
S
C8H17
C8H17
N
S
Pd(PPh3
)
,
4
(HO)2
B
CHO
O
ODT
UV-vis absorption and electrochemical characterization
OHC
CHO
K2CO3, H2O, (CH2OMe)2, N2, reflux
P(OEt)3, toluene, N2, reflux
C2
The UV-Vis absorption spectra of DTF-C5 and DTF-C6 in dilute
THF solution are shown in Fig. 3a and 3b. The corresponding
spectroscopic parameters extracted are summarized in Table 1.
The two sensitizers exhibit strong absorption band in the range
of 400-450 nm, which can be attributed to the intramolecular
charge transfer effect between the donor and acceptor. The
absorption maximum (λmax) was observed at 429 nm (molar
extinction coefficient ε = 3.90×104 M-1 cm-1) for DTF-C5 and 431
nm (ε = 3.10×104 M-1 cm-1) for DTF-C6. The little bathochromic
shift of λmax and absorption onset of DTF-C6 can be attributed
to the more electron-rich character of phenoxazinemoiety than
that of thiophene.
In comparison with their absorption spectra in THF solution,
the profiles of the absorption spectra of TiO2 films (4μm) with
these sensitizers loading show dramatically broaden and red-
shift absorption, as shown in Fig. 3c. These observations can
be related to the formation of aggregates of these sensitizers
on the TiO2 surfaces, such as J-aggregates. It was also found
that the broadened absorption band and the red-shifted
absorption onsets by about 100 nm on the thin film should
afford increased light harvesting.
C4H9
N
C4H9
N
2-cyanoacetic acid, piperidine
chloroform,
O
S
CN
S
S
C8H17
C8H17
O
, refiux
N2
S
S
S
S
C8H17
C8H17
COOH
S
CHO
DTF-C6
D2
Scheme 1. Synthetic routes to DTF-C5 and DTF-C6.
Results and discussion
Synthesis
The synthesis of DTF-C5 and DTF-C6 follow the previously
reported stragety.35 Bromination of compound A with NBS
produced the brominated phenoxazine derivative B. Compound
C2 was obtained by Suzuki reaction of 4-formylphenylboronic
acid with B. Compounds C1 and C2 were then subjected to a
phosphite-induced Horner-Wittig condensation with ODT to
produce the key intermediates D1 and D2. Finally, the π-extend
DTF-bearing aldehydes D1 and D2 were, respectively, reacted
with cyanoacetic acid in the presence of piperidine via the
Knoevenagel reaction to give the target sensitizer compounds
DTF-C5 and DTF-C6. The chemical structures of DTF-C5 and DTF-
C6 were fully characterized by H NMR, 13C NMR and mass
1
The molecular orbital energy levels of DTF-C5 and DTF-C6
were derived from CV (Fig. 3d) in combination with the
spectrometry. Both DTF-C5 and DTF-C6 showed good solubility
in common organic solvents such as dichoromethane,
tetrahydrofuran (THF) and toluene.
Theoretical calculations
To understand the shapes of the two sensitizers, molecular
geometries were first evaluate by density functional theory
(DFT) calculations at the B3LYP/6-31G* level using methyl-
substituted molecule as the model compound. It was found that
DTF-C5 and DTF-C6 adopted distinct shapes from each other
due to the different π-bridges, as shown in Fig. 2a. Molecule
DTF-C5, whose π-bridge incorporated two phenyls substitueted
at the 2- and 5- positions of the thiophene unit respectively,
possessed a larger flare angle of 150.6o between the donor and
acceptore units. On the other hand, molecule DTF-C6, whose π-
bridge incorporated two phenyls substitueted at the 3- and 7-
positions of the phenoxazine unit, possessed a typical V-shaped
conformation with a smaller flare angle of 120.6o. These results
indicate that DTF-C5 molecules may trend to form more
ordered and compact dye aggregates in the solid state
compared to DTF-C6 molecules.
In ordered to understand the photo-induced charge
separation of DTF-C5 and DTF-C6, the DFT calculations were
performed on electron-density distribution of the HOMOs and
Fig. 2 (a) Optimized molecular geometry of DTF-C5 and DTF-C6 based on B3LYP/6-
31G* level and (b) Electron-density distributions for the HOMOs and LUMOs of
the DTF-C5 and DTF-C6.
4 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Page 5 of 9
Journal of Materials Chemistry C
Please do not adjust margins
Journal Name
ARTICLE
View Article Online
(b)
(a)
with CDCA (10 mM) based DSCs presDeOnIt:e1d0.10a39d/Cra8mTCa0t6ic1a09llBy
decreased PCE of 4.8%, which can be mainly contributed to the
decreased Jsc and FF values (Jsc= 10.04 mA/cm2, and FF = 0.61).
From Table 2, it could be found that the absorbed amounts of
pristine DTF-C5 in the non-coadsorbent device are higher than
those in the CDCA co-adsorbed cells. This result indicates DTF-
C5, which adopts a large flare angle and looks like a nearly-linear
molecule to some extent, tend to form more ordered and
compact aggregates by pristine dye molecules on TiO2 films.
Therefore, comparing to pristine DTF-C5 based DSCs, the DSCs
based on DTF-C5 co-adsorbed with CDCA exhibited lower Jsc and
PCE due to the competive adsorbing of CDCA. However, such
results were quite different from the case of DSCs based on DTF-
C6 which possessed a reduced flare angle. As illustrated in Fig.
4b, the DSCs based on pristine DTF-C6 provide a moderate PCE
of 5.5%, with a Jsc of 12.44 mA/cm2, a Voc of 710 mV and a FF of
0.62. In comparison with pristine DTF-C5 based DSCs, such a
decreased Jsc and Voc of pristine DTF-C6 based DSCs is counter
to their absorption in Fig. 3. However, after co-adsorbing CDCA
(10 mM) with DTF-C6 onto TiO2 surface, the resulted DSCs
dramatically uplift the PCE to 9.04%, accompanied with higher
Jsc and Voc values (Jsc= 15.76 mA/cm2, and Voc = 790 mV).
Considering the absorbed amounts of DTF-C6 co-adsorbed with
CDCA based cells are lower than those in pristine DTF-C6 based
cells (Table 2), it can suggest that the dye-aggregated motifs of
pristine DTF-C5 and DTF-C6 are different from each other on the
TiO2 surface. There may be more vacant sites on the TiO2
surface between the DTF-C6 aggregates. This is because DTF-C6
adopts a relative smaller flare angle and more twisted
DTF-C6
DTF-C5
1.0
0.8
0.6
0.4
0.2
0.0
1.0
0.8
0.6
0.4
0.2
0.0
300
400
500
600
700
800
300
400
500
600
700
800
Wavelength (nm)
Wavelength (nm)
(c)
(d)
DTF-C5
DTF-C6
1.0
0.8
0.6
0.4
0.2
0.0
DTF-C5
DTF-C6
400
500
600
700
-2
-1
0
1
2
+
Wavelength (nm)
Potential / V vs Fc / Fc
Fig. 3 UV-Vis absorption and PL spectra of (a) DTF-C5 and (b) DTF-C6 in dilute THF
solution (1×10−5 mol L −1), (c) normalized UV-vis spectra of DTF-C5 and DTF-C6 on
TiO2 films, and (d) Cyclic voltammograms of DTF-C5 and DTF-C6 in DMF.
excitation transition energies (E0-0
) determined by the
intersection of absorption and photoluminescence spectra (Fig.
3a and 3b), and are presented in Table 1. The first oxidation
potentials (Eox) of the ground state of DTF-C5 and DTF-C6 are
corresponding to their highest occupied molecular orbital
(HOMO) levels. The Eox of DTF-C5 and DTF-C6 was 0.86V and
0.93V, corresponding to HOMO level of -5.26 eV and -5.73 eV,
respectively. Obviously, the HOMO levels of the two sensitizers
are more positive than the iodide/triiodide couple (0.4 V vs.
NHE), indicating a thermodynamically downhill regeneration of
the photo oxidized sensitizers by accepting electrons from the
surrounding I- ions. The lowest unoccupied orbital (LUMO)
energy levels of DTF-C5 (-1.63 V) and DTF-C6 (-1.49 V),
calculated as Eox-E0-0, are sufficiently negative relative to the
conduction-band edge of TiO2 (-0.5 V vs. NHE), ensuring an
efficient thermodynamic driving force for the electron injection.
Photovoltaic performance
molecular strucuture, which supresses
compact dye-
aggregates forming. To this end, the maximum performance of
DTF-C6 based DSCs can not be presented. Therefore, co-
adsorbance with CDCA is necessary for DTF-C6 to maximize the
DSCs‘ performance as the ingomogeneous distribution of the
dye aggregates throughtout the TiO2 surface would lead to
current loss and adverse electron recombination. It was noted
that the absorbed amounts of the dye was in the order of
pristine dye absorption > with CDCA co-adsorption. However,
the Jsc values of the DSCs decrease in the order of DTF-C6 co-
adsorbed with CDCA > pristine DTF-C5 > pristine DTF-C6 > DTF-
C5 co-adsorbed with CDCA. This result clearly indicates that
reasonable regulation of molecular shapes and aggregations on
TiO2 is an important issue to maximum the performance of
DSCs.
In order to evaluate the strategy to maximize the performance
of DSCs based on organic dyes with different molecular shapes.
The devices based the DTF-C5 and DTF-C6 absorbedon TiO2
films with and without CDCA were investigated. The cells were
measured under an irradiance of 100 mW cm-2, simulated AM
1.5G sunlight, relevant photovoltaic parameters are collected in
Table 2. As shown in Fig. 4a, the champion DSCs based on
pristine DTF-C5 exhibited a Jsc and Voc of 14.92 mA cm-2 and 759
mV, respectively, combining with a fill factor (FF) of 0.65,
leading to a high PCE of 7.39%. In contrast, DTF-C5 co-adsorbed
The incident photon-to-current conversion efficiency (IPCE)
spectra shown in Fig. 4 have confirmed the trend of Jsc variation.
Table 1 Absorption and electrochemical properties of DTF-C5 and DTF-C6.
λabs
ε
Eox
E0-0
Eox-E0-0
HOMO
(ev)
LUMO
(ev)
max
Sensitizer
(nm)
(M-1 cm-1)
(V vs NHE)
(ev)
(V vs NHE)
DTF-C5
DTF-C6
429
431
3.90×104
3.10×104
0.86
0.93
2.49
2.42
-1.63
-1.49
-5.26
-5.73
-2.77
-3.31
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 5
Please do not adjust margins

Please do not adjust margins
Journal of Materials Chemistry C
Page 6 of 9
View Article Online
DOI: 10.1039/C8TC06109B
Journal Name
ARTICLE
-12
(a)
(a)
15
(b)
(b)
-12
-10
-8
15
12
9
-10
-8
12
9
-6
-6
6
6
DTF-C6 with CDCA
pristine DTF-C6
-4
-2
0
pristine DTF-C5
DTF-C5 with CDCA
pristine DTF-C5
DTF-C5 with CDCA
DTF-C6 with CDCA
pristine DTF-C6
-4
3
3
-2
0
0.0
0
0.0
0
0.2
0.4
0.6
0.8
1.0
0.2
0.4
0.6
0.8
1.0
0
5
10
15
20
25
0
5
10
15
20
25
Voltage (V)
Voltage (V)
Z'' (ohm)
Z'' (ohm)
Fig. 5 The Nyquist plots of (a) DTF-C5 and (b) DTF-C6 based DSCs.
100
100
80
60
40
20
0
(c)
(d)
80
60
40
20
0
charge recombination, thus giving a higher Voc. The Nyquist
plots for the DSCs based on the sensitizers with or without
CDCA co-adsorbent are displayed in Fig. 5. In the case of DTF-
C5, the Rrec values trend in the order of pristine DTF-C5 > DTF-
C5 co-adsorbed with CDCA, while the trend for DTF-C6 is turned
toDTF-C6 co-adsorbed with CDCA > DTF-C6. These results are in
good consistent with the Voc values of the DSCs according to
Table 2. Based on these, it can be suggested that compact dye-
aggregates of DTF-C5 form a thick dye layer, thus preventing
redox electron acceptors from approaching the TiO2 efficiently;
however, the vacant sites between dye-aggregates of DTF-C6
need CDCA attendance to eliminate the adverse charge
recombination.
pristine DTF-C5
DTF-C5 with CDCA
DTF-C6 with CDCA
pristine DTF-C6
400
450
500
550
600
650
700
400 450 500 550 600 650 700 750
Wavelength (nm)
Wavelength (nm)
Fig. 4 J-V curves of (a) DTF-C5 and (b) DTF-C6 based DSCs. Incident photon to
current efficiency (IPCE) spectra of (c) DTF-C5 and (d) DTF-C6 based DSCs.
Comparing to the DSC based on DTF-C5 co-adsorbed with CDCA
that exhibits a narrow and relatively low IPCE values (slightly
higher than 60%), the DSC based on pristine DTF-C5 exhibits
remarkably broadened and increased IPCE (magnitude with
values reach 90%) action spectra that covers the visible region.
In the case of DTF-C6, however, the DSC based on DTF-C6 co-
adsorbed with CDCA gives broader and higher IPCE value
(magnitude with values over 95%) than that of pristine DTF-C6
based DSC. Taken the dye absorbed amounts and molecular
shape into together, this difference in IPCE shows that the
pristine compact dye aggregates of the DTF-C5 that with a large
flare angle on TiO2 films lead to enhanced light absorption
capabilities and charge carrier injection, thus raising the Jsc. On
the other hand, the typical V-shaped DTF-C6 that possesses a
reduced flare angle needs the addition of CDCA to fill up the
vacant sites between the dye aggregates on the surface of TiO2,
and reduce the current loss.
Conclusion
In summary, two dithiafulvene-based sensitizers DTF-C5 and
DTF-C6 differing in molecular shapes have been developed to
study the relationship between molecular shapes and dye
aggregations in one dye system to maximize the performance
of DSCs. Our results demonstrate that sensitizer DTF-C5 with a
larger angle between the donor and acceptor units tends to
form compact dye-aggregates on the TiO2 surface without
losing the amount of absorbed dyes, passivating the surface to
reduce the electron recombination and ensuring optimized Jsc
and Voc values. For typical V-shaped sensitizer DTF-C6 with a
reduced flare angle, it is necessary to introduce CDCA co-
adsorbent to fill up the vacant sites between their dye-
aggregates to reduce the current loss and electron
recombination. As a result, a DSC with a PCE of 7.39% was
obtained in the pristine DTF-C5 based devices. With a little
bathochromic absorption, an impressive PCE of 9.04% was
realized in DTF-C6 co-adsorbed with CDCA based DSCs. The
primary findings give insights to maximum DSCs performance
based on different shape of organic sensitizers.
Electrochemical impedance spectroscopy analysis
To further elucidate the photovoltaic results and display more
dynamic information of the interfacial charge transfer process
in DSCs sensitized by DTF-C5 and DTF-C6 absorbed on TiO2
films with and without CDCA, electrochemical impedance
spectroscopy (EIS) was performed in dark under a forward bias
of 0.6 V with a frequency range of 0.1Hz - 100 kHz. Generally,
the Rrec corresponding to the larger semicircle is related to the
charge recombination rate between the TiO2 film and the
electrolyte. In principle, a larger Rrec value indicates a slower
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 6
Please do not adjust margins

Please do not adjust margins
Journal of Materials Chemistry C
Page 7 of 9
View Article Online
DOI: 10.1039/C8TC06109B
Journal Name
ARTICLE
Table 2 Photovoltaic performance of DSCs based on DTF-C5 and DTF-C6.
Conc of
CDCA
Jsc
Voc
[mV]
FF
η
[%]
Dye absorbed amounts
Sensitizer
[mA cm-2]
[mol cm-2]
10.04±0.15
760±1.4
0.61±0.01
4.80±0.06
(1.95±0.1) ×10-7
DTF-C5
DTF-C5
DTF-C6
DTF-C6
10mM
--
14.92±0.21
15.76±0.17
12.44±0.57
759±2.2
790±1.1
0.65±0.004 7.39±0.03
0.72±0.006 9.04±0.04
(2.68±0.1) ×10-7
(2.13±0.1) ×10-7
(2.86±0.1) ×10-7
10mM
--
710±0.63 0.62±0.008 5.50±0.02
12 J. Gao, A. M. El-Zohry, H. Trilaksana, E. Gabrielsson, V. Leandri,
H. Ellis, L. D’Amario, M. Safdari, J. M. Gardner, G. Andersson
and L. Kloo, ACS Appl. Mater. Interfaces, 2018, 10, 26241-
26247.
13 P. Liu, B. Xu, K. M. Karlsson, J. Zhang, N. Vlachopoulos, G.
Boschloo, L. Sun and L. Kloo, J. Mater. Chem. A, 2015, 3, 4420-
4427.
Conflicts of interest
There are no conflicts to declare.
14 Y. Huang, W.-C. Chen, R. Ghadari, X.-P. Liu, X.-Q. Fang, T. Yu
and F.-T. Kong, J. Power Sources, 2018, 396, 559-565.
15 I. Chung, B. Lee, J. He, R. P. H. Chang and M. G. Kanatzidis,
Nature, 2012, 485, 486-489.
16 M. J. Ju, I.-Y. Jeon, K. Lim, J. C. Kim, H.-J. Choi, I. T. Choi, Y. K.
Eom, Y. J. Kwon, J. Ko, J.-J. Lee, J.-B. Baek and H. K. Kim, Energy
Environ. Sci., 2014, 7, 1044-1052.
Acknowledgements
This work was supported by the National Natural Scientific
Foundation of China (NO. 21303117, 61605138), the Natural
Science Foundation of Shanxi Province (201601D011031,
201601D202030), the Shandong Provincial Natural Science
Foundation of China (ZR2017MA024), and the Fundamental
Research Funds for the Central Universities (18CX05011A).
17 Z. Yao, M. Zhang, H. Wu, L. Yang, R. Li and P. Wang, J. Am.
Chem. Soc., 2015, 137, 3799-3802.
18 K. Kakiage, Y. Aoyama, T. Yano, K. Oya, J. Fujisawa and M.
Hanaya, Chem. Commun., 2015, 51, 15894-15897.
19 K. Guo, K. Yan, X. Lu, Y. Qiu, Z. Liu, J. Sun, F. Yan, W. Guo and
S. Yang, Org. Lett., 2012, 14, 2214-2217.
References
1
2
3
4
5
6
7
8
9
I.-P. Liu, W.-H. Lin, C.-M. Tseng-Shan and Y.-L. Lee, ACS Appl. 20 J. Cheng, Y. Cao, X. Liang, J. Zheng, F. Zhang, S. Wei, X. Lu, K.
Mater. Interfaces, 2018, 10, 38900-38905.
Guo and S. Yang, Mater. Chem. Phys., 2017, 192, 349-355.
H. He, C. Zhang, T. Liu, Y. Cao, N. Wang and Z. Guo, J. Mater. 21 J. Cheng, F. Zhang, K. Li, J. Li, X. Lu, J. Zheng, K. Guo, S. Yang
Chem. A, 2016, 4, 9362-9369.
and Q. Dong, Dyes Pigm., 2017, 136, 97-103.
K. Xie, M. Guo and H. Huang, J. Mater. Chem. C, 2015, 3, 22 J. Cheng, X. Liang, Y. Cao, K. Guo and W.-Y. Wong,
10665-10686.
Tetrahedron, 2015, 71, 5634-5639.
X. Zhang, T. Peng and S. Song, J. Mater. Chem. A, 2016, 4, 23 Y. Cao, J. Cheng, F. Zhang, X. Liang, J. Li, K. Guo and S. Yang,
2365-2402.
Sci. China-Mater., 2016, 59, 797-806.
M. Pastore, T. Etienne and F. De Angelis, J. Mater. Chem. C, 24 C.-C. P. Chiang, C.-Y. Hung, S.-W. Chou, J.-J. Shyue, K.-Y. Cheng,
2016, 4, 4346-4373.
X. Zhang, F. Gou, D. Zhao, J. Shi, H. Gao, Z. Zhu and H. Jing, J.
Power Sources, 2016, 324, 484-491.
M. Pazoki, U. B. Cappel, E. M. J. Johansson, A. Hagfeldt and G.
Boschloo, Energy Environ. Sci., 2017, 10, 672-709.
P.-J. Chang, Y.-Y. Yang, C.-Y. Lin, T.-K. Chang, Y. Chi, H.-L. Chou
and P.-T. Chou, Adv. Funct. Mater., 2018, 28, 1703282.
25 L. Favereau, Y. Pellegrin, L. Hirsch, A. Renaud, A. Planchat, E.
Blart, G. Louarn, L. Cario, S. Jobic, M. Boujtita and F. Odobel,
Adv. Energy. Mater., 2017, 7, 1601776.
W.-C. Yu, L.-Y. Lin, W.-C. Chang, S.-H. Zhong and C.-C. Su, J. 26 Y. P. Fu, H. W. Wu, S. Y. Ye, X. Cai, X. Yu, S. C. Hou, H. Kafafy
Power Sources, 2018, 403, 157-166.
and D. C. Zou, Energy Environ. Sci., 2013, 6, 805-812.
M. Janani, P. Srikrishnarka, S. V. Nair and A. S. Nair, J. Mater. 27 Y. Yang, H. Zhang, Z.-H. Lin, Y. Liu, J. Chen, Z. Lin, Y. Zhou, C. P.
Chem. A, 2015, 3, 17914-17938.
Wong and Z. L. Wang, Energy Environ. Sci., 2013, 6, 2429-
2434.
28 Z. Yao, M. Zhang, H. Wu, L. Yang, R. Li and P. Wang, J. Am.
Chem. Soc., 2015, 137, 3799-3802.
29 D. Moia, T. Leijtens, N. Noel, H. J. Snaith, J. Nelson, P. R. F.
Barnes, Adv. Mater., 2015, 27, 5889-5894.
10 P. Chal, A. Shit and A. K. Nandi, J. Mater. Chem. C, 2016, 4,
272-285.
11 K. Li, J. Xu, W. Shi, Y. Wang and T. Peng, J. Mater. Chem. A,
2014, 2, 1886-1896.
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 7
Please do not adjust margins

Please do not adjust margins
Journal of Materials Chemistry C
Page 8 of 9
ARTICLE
Journal Name
30 J. M. Cole, M. A. Blood-Forsythe, T.-C. Lin, P. Pattison, Y. Gong,
Á. Vázquez-Mayagoitia, P. G. Waddell, L. Zhang, N. Koumura
and S. Mori, ACS Appl. Mater. Interfaces, 2017, 9, 25952-
25961.
View Article Online
DOI: 10.1039/C8TC06109B
31 X. Lu, Y. Shao, S. Wei, Z. Zhao, K. Li, C. Guo, W. Wang and W.
Guo, J. Mater. Chem. C, 2015, 3, 10129-10139.
32 J. Cong, X. Yang, L. Kloo and L. Sun, Energy Environ. Sci., 2012,
5, 9180-9194.
33 G. A. Sewvandi, Z. Tao, T. Kusunose, Y. Tanaka, S. Nakanishi
and Q. Feng, ACS Appl. Mater. Interfaces, 2014, 6, 5818-5826.
34 Y. Li, X. Zhang and M. J. Ko, ACS Sustainable Chem. Eng., 2018,
6, 7193-7198.
35 P. Brogdon, H. Cheema and J. H. Delcamp, ChemSusChem,
2017, 10, 3624-3631.
36 Z. Yang, J. Deng, H. Sun, J. Ren, S. Pan and H. Peng, Adv.
Mater., 2014, 26, 7038-7042.
37 Z. Zhang, X. Chen, P. Chen, G. Guan, L. Qiu, H. Lin, Z. Yang, W.
Bai, Y. Luo and H. Peng, Adv. Mater., 2014, 26, 466-470.
38 T. Chen, L. Qiu, Z. Yang and H. Peng, Chem. Soc. Rev., 2013, 42,
5031-5041.
39 H. Zhang, Z. Iqbal, Z.-E. Chen and Y. Hong, Electrochim. Acta,
2018, 290, 303-311.
40 W. Ying, F. Guo , J. Li , Q. Zhang, W. Wu, H. Tian, J. Hua, ACS
ACS Appl. Mater. Interfaces, 2012, 4, 4215-4224.
41 R. Lin, H. Lin, Y. Yen, C. Chang, H. Chou, P. Chen, C. Hsu, Y.
Chen, J. T. Lin, K. Ho, Energy Environ. Sci., 2013, 6, 2477-2486.
42 A. Michaleviciute, M. Degbia, A. Tomkeviciene, B. Schmaltz, E.
Gurskyte, J. V. Grazulevicius, J. Bouclé and F. Tran-Van, J.
Power Sources, 2014, 253, 230-238.
43 H. Shahroosvand, P.
Abbasi, B. Nemati Bideh,
ChemistrySelect, 2018, 3, 6821-6829.
44 M. Urbani, E. M. Barea, R. Trevisan, A. Aljarilla, P. de la Cruz,
J. Bisquert, F. Langa, Tetrahedron Lett., 2013, 54, 431-435.
45 A. Michaleviciute, M. Degbia, A. Tomkeviciene, B. Schmaltz, E.
Gurskyte, J. Vidas Grazulevicius, J. Bouclé, F. Tran-Van, J.
Power Sources, 2014, 253, 230-238.
46 Y. Ooyama, S. Inoue, T. Nagano, K. Kushimoto, J. Ohshita, I.
Imae, K. Komaguchi and Y. Harima, Angew. Chem. Int. Ed.,
2011, 50, 7429-7433.
47 J.-M. Ji, H. Zhou and H. K. Kim, J. Mater. Chem. A, 2018, 6,
14518-14545.
48 W. Lee, J. Choi, J. W. Namgoong, S. H. Kim, K. C. Sun, S. H.
Jeong, K. Yoo, M. J. Ko and J. P. Kim, Dyes Pigm., 2014, 104,
185-193.
49 D. Sipaviciute, D. Tavgeniene, G. Krucaite, D. Volyniuk, J. V.
Grazulevicius, B. Yao, Z. Xie, B. Zhang and S. Grigalevicius, Dyes
Pigm., 2017, 137, 208-213.
50 W. Lee, S. B. Yuk, J. Choi, H. J. Kim, H. W. Kim, S. H. Kim, B. Kim,
M. J. Ko and J. P. Kim, Dyes Pigm., 2014, 102, 13-21.
8 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Page 9 of 9
Journal of Materials Chemistry C
View Article Online
DOI: 10.1039/C8TC06109B
Graphical Abstract
Dithiafulvene-based sensitizers with different flare angles need to coordinate different
dye aggregations to maximize the performance of dye-sensitized solar cells.