Cost-Effective Anthryl Dyes for Dye-Sensitized Cells under One Sun

Oct 5, 2015 - Cost-Effective Anthryl Dyes for Dye-Sensitized Cells under One Sun and Dim Light. Chin-Li Wang† ... 4152; E-mail: [email protected]. Cit...
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Cost-Effective Anthryl Dyes for DyeSensitized Cells Under One Sun and Dim Light Chin-Li Wang, Pao-Tsen Lin, Yi-Fen Wang, Chiung-Wen Chang, BoZhi Lin, Hshin-Hui Kuo, Cheng-Wei Hsu, Shih-Hung Tu, and Ching-Yao Lin J. Phys. Chem. C, Just Accepted Manuscript • DOI: 10.1021/acs.jpcc.5b08101 • Publication Date (Web): 05 Oct 2015 Downloaded from http://pubs.acs.org on October 9, 2015

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Cost-effective Anthryl Dyes for Dye-sensitized Cells under One Sun and Dim Light Chin-Li Wang,a Pao-Tsen Lin,a Yi-Fen Wang,a Chiung-Wen Chang,a Bo-Zhi Lin,a Hshin-Hui Kuo,a Cheng-Wei Hsu,b Shih-Hung Tu,b Ching-Yao Lina,* a

Department of Applied Chemistry, National Chi Nan University, Puli, Nantou 54561, Taiwan.

b

Taiwan DSC PV Ltd., Taoyuan 33759, Taiwan.

KEYWORDS Dye-sensitized cell, organic dye, anthracene, dim-light. ABSTRACT: A series of anthracene-based organic dyes were prepared via cost-effective synthetic procedures for dyesensitized cell application. UV-visible and fluorescent spectra, electrochemical properties as well as photovoltaic performance of the dyes were studied. Under one sun (100 mW/cm2), the AN-3 small cell outperforms others in the series. Under a dim light condition, the AN-3 modules showed PCE comparable to that of the Z907 modules. After optimizing the synthetic procedure, we found that AN-3 can be manufactured at a fairly low price.

Dye-sensitized cell (DSC) has been drawing considerable attention in recent years owing to its lower production cost and the diversity of colorful dyes.1~3 Power conversion efficiency (PCE) of DSCs using polypyridyl Ru(II) complexes, organic molecules and porphyrin sensitizers have all exceeded 10 %.4~10As in the case of metallo-sensitizers, small organic molecules have also been under rapid development due to their environmental friendliness, low cost, ease of synthesis and structural diversity.11 Recently, a PCE of 12.5 % has been reported with an N-annulated indenoperylene dye by Wang and co-workers.10 For most photo-sensitizers, donor-π spacer-acceptor is the most effective molecular design. This has been seen in porphyrins as well as in small organic dyes.11,12 For organic dyes, conjugated aromatic compounds, such as phenyl,13 thiophene,14 fluorene,15 EDOT16 and furan,17 are often used as the π-spacers. Among the above-mentioned compounds, anthracene is especially of interest in this work because of its low price and usefulness in various applications. For example, anthracenes bearing arylamines are known for their blue-luminescing and hole-transporting properties.18,19 Anthracene derivatives can also be used in organic thin film transistors (OFET)20,21 and organic solar cells.22 For DSCs, there have been only a few examples in the literature regarding anthracene-based photo-sensitizers. In 2009, anthracence dyes bearing cyanoacrylic acid or manolic acid were studied to compare their semiconductor binding ability by Srinivas et. al.23 In 2010, an anthracene derivative bearing a triarylamine donor and a cyanoacrylc acid acceptor was reported to attained a PCE of

7.03 % by Sun and co-workers.24 In 2011, 2,6-di-tert-butyl groups were attached to anthracence to lessen molecular aggregation and to increase the solubility by Thomas and co-workers.25 In 2013, Lin, Ho and co-workers reported anthracene dyes with long alkoxyl chains at the 9 and 10 positions to prevent dye aggregation. An impressive PCE of 9.11 % was achieved with the said dye.26 To the best of our knowledge, this is perhaps the most efficient athracene-based photo- sensitizers to date. Previously, two anthracence-based dyes were briefly mentioned as co-sensitizers or co-adsorbents to improve porphyrin-based DSCs.27,28 In this work, the synthesis, fundamental properties, and photovoltaic performance of five anthracene-based dyes (denoted as AN-x) are reported in more details. The molecular structures of the AN-x dyes are shown in Chart 1. As shown in the chart, all AN-x dyes consist of an anthracence unit, a dialkylaminophenyl donor, and an anchoring acid group. Ethyne is used as the bridging unit because of its linear chemical structure and the efficient charge/electron transfer.29,30 By comparing AN-1 and AN-3, the differences between the dimethylamine and the dioctylamine donors can be observed. By comparing AN-5 or AN-7 with AN-3, the extra electro-withdrawing groups at the anchoring benzoic acid can be examined. By comparing AN-8 with AN-3, we wish to examine the effects of replacing benzoic acid with cyanoacrylic acid. For photovoltaic properties, J-V and IPCE measurements were carried out to evaluate the AN-x dyes. Because of its better performance among the dyes under investigation (vide infra), photovoltaic properties of the

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AN-3 small-cell (area = 0.16 cm2) and larger flexible panels (area = 36 cm2) were studied under simulated AM 1.5 irradiation (100 mW/cm2) and dim-light (200, 600, and 1000 Lux) conditions. Studying photovoltaic performance under dim-light conditions is of interest because indoor applications of DSCs have potentials in decorations, biosensors and Internet of Things (IoT), etc.31,32

Chart 1. Chemical structures of the AN-x dyes.

Experimental Section Materials Air-sensitive solids were handled in a glovebox (MBraun Unilab). A vacuum line and standard Schlenk techniques were employed to process air-sensitive solutions. Solvents for the synthesis (ACS Grade) were CH2Cl2 and CHCl3 (Mallinckrodt Baker), hexanes (Haltermann, Hamburg, Germany), and THF (Merck, Darmstadt, Germany). These solvents were used as received unless otherwise stated. Other chemicals were obtained commercially (Acros Organics). THF for cross-coupling reactions was purified and dried with a solvent purification system (Asiawong SD-500, Taipei, Taiwan); about 50 ppm of H2O was found in the resulting fluid. For electrochemical measurements, THF was distilled over sodium under N2. Pd(PPh3)4 catalyst (Strem) were used as received. For chromatographic purification, we used silica gel 60 (230−400 mesh, Merck). Instruments NMR spectra (Bruker Avance II 300 MHz NMR Spectrometer at National Chi Nan University), elemental analyses (ElementarVario EL III, Precision Instrumentation Center at National Taiwan University or MOST Instrumentation Center at National Chung Hsing University), mass spectra (Microflex MALDI-TOF MS, Bruker Daltonics), electrochemical measurements (CHI Electrochemical Workstation 611A), absorption spectra (Agilent 8453 UV-Visible spectrophotometer) and fluorescence spectra (Varian Cary Eclipse fluorescence spectrometer) were recorded with the indicated instruments. Device fabrication and characterization The DSSC devices were fabricated with a titania working electrode and a Pt-coated counter electrode in a structure of sandwich type. For the working electrode, the TiO2 paste was

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coated onto a TiCl4-treated FTO glass substrate (TEC 7, Hartford, USA) to obtain a film of thickness 18 µm with repetitive screen printing. The film thickness of a scattering layer was 6 µm and the active size of the device was 0.5×0.5 cm2. The TiO2 films were then annealed according to a programmed procedure. The annealed films were treated with fresh TiCl4 aqueous solution (40 mM) at 70 °C for 30 min and sintered at 500 °C for 30 min. The dye uptake of AN-x dyes on these TiO2 films was performed in a solution (0.20 mM) a mixture of toluene and ethanol with a volume ratio 1/2 at 25 °C for 2 hours. The CDCA (1.0 mM) c0-adsorbent was added during dye uptake process to prevent dye aggregation. The dye-loadings were estimated by treating the photoanodes with a THF solution (known volume) containing 0.1M TBAOH to desorb the dye from the TiO2 surfaces. The concentrations of the solutions were determined by UV-visible spectrometry. The dye-loadings were then calculated from the known volumes and the determined concentrations. The counter electrode was made with repetitive screen printing of Pt paste onto a FTO glass substrate through a typical procedure of thermal decomposition. The two electrodes were assembled into a cell of sandwich type and sealed with a spacer of thickness 25 µm. The electrolyte injected into the device contained I2 (0.05 M), LiI (0.1 M), PMII (1.0 M), 4-t-butylpyridine (0.5 M) in a co-solvent containing acetonitrile and valeronitrile with a volume ratio 85/15. The flexible 36-cm2 panels (an opaque TiO2 film, 12 µm thick, without a scattering layer, the TiO2 nano-particle size is 200~300nm) were prepared by Taiwan DSC PV Ltd. The current-voltage (J–V) characteristics of the DSSC devices covered with a black mask (aperture area 0.4×0.4 cm2) were determined with a solar simulator (AM 1.5G, SS50 AAA-EM, PET) and a source meter (Keithley 2400). The measurement of the incident photon-to-current conversion efficiency (IPCE) was performed by the 7-SCSpec system (Sofn Instruments Co., Ltd.) with a source meter (Keithley 2000). The dim light conversion efficiency measurement system was purchased from Yu-Yi Enterprise Co., Ltd, Taiwan with a spectrophotometer (Ocean Optics USB2000+UV-VIS) and a source meter (Keithley 2401). The T5, T8 and LED fluorescent lights were manufactured by China Electric MFG. Co.. Results and Discussion Synthesis and production cost Chart 2 illustrates the preparation procedures of the AN-x dyes. More detailed information is available in the Supporting Information. As shown in the chart, Sonogashira cross-coupling method was used to synthesize the AN-x dyes.33 All starting materials, including 9,10-dibromoanthracene, 4-ethynyl-N,Ndimethylaniline, and halogenated compounds, are commercially available. For compounds 1 and 2, crosscoupling 9,10-dibromoanthracene with suitable electrondonors gave mono-substituted precursors at 51 ~ 56 % yields.28 AN-1 was obtained by further cross-coupling

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compound 1 with 4-ethynyl benzoic acid at 60.1 % yield. For other dyes, compound 2 was reacted with suitable halogenated reagents to give 93.5 % of AN-3, 81.1 % of AN5, 77.5 % of AN-7 and 73.8 % of compound 3. According to the Knoevenagel reaction,34 reacting compound 3 with cyanoacrylic acid gave AN-8 at 42.o % yield. Because of AN-3's higher yield and better photovoltaic performance, its synthetic procedure was optimized in order to lower the production cost. The gram-scale production of AN-3 (including the consumables, labor, electricity, and waste disposal fee, etc.) is estimated to be less than US$ 65/g.

of AN-1, AN-3, AN-5, AN-7 and AN-8 are located at 600, 603, 613, 613 and 615 nm, respectively, consistent with the UV-visible absorption spectra. Interestingly, the fluorescence intensities of AN-8 and AN-7 are noticeably lower than those of other AN dyes in the series.

O N OH Br

Br

N

Br

O N OH

1 (56.7 %)

AN-1 (60.1 %)

O I OH

C 8H17 N C 8H17

O OH

AN-3 (93.5 %) F O F

Br OH

C 8H17 N C 8H17

O

Figure 1. Absorption spectra of AN-x in THF.

OH

AN-5 (81.1 %) C 8H 17 N C 8H 17

NO 2 O Br OH

2

C 8H17 N C 8H17

NO2 O OH

AN-7 (77.5 %) O I

C 8H 17 N C 8H 17

O

3 (73.8 %) N

NC C8H17 N C8H17

O C

OH

OH O

AN-8 (42.0 %)

Chart 2. Preparation of AN-x. Spectral and electrochemical properties The UVvisible absorption spectra of AN-x in THF are compared in Figure 1. The wavelengths and absorption coefficients are collected in Table 1. All AN-x dyes absorb light around 500 nm. The molar extinction coefficients (ε) of the AN-x dyes are roughly 3 times greater than that of the N719 dye (ε = 14100 M-1cm-1).35 Comparing AN-3 with AN-1, it is obvious that the absorption band of AN-3 is red-shifted and intensified from that of AN-1. This phenomenon may be attributed to the two octyl chains of AN-3 and is consistent with the literature report.36 With additional electron-withdrawing groups at the anchoring groups, AN-5 (-F) and AN-7 (-NO2) display further red-shifted absorption bands from that of AN-3. With a different anchoring group, AN-8 gives rise to the most red-shifted absorption band in the series, consistent with the literature reports.13 Upon adsorbing onto TiO2 films, the absorption bands of AN-x are blue-shifted and broadened (Figure S1). This phenomenon may be attributed to dye aggregation or/and de-protonation of the anchoring groups.37-39 Fluorescence spectra of AN-x are compared in Figure 2, with the maximum wavelengths listed in Table 1. As shown in the figure and table, the fluorescence emissions

-6

Figure 2. Fluorescence spectra of AN-x in THF (2x10 M).

For electrochemistry, cyclic voltammograms of AN-x dyes are compared in Figure 3 and the redox potentials are gathered in Table 1. For the oxidations (Figure 3a), all AN-x dyes demonstrate less reversible reactions. Therefore, differential pulsed voltammetry (DPV) was employed to estimate the oxidation potentials of AN-x dyes. The oxidation potentials were estimated to be +0.86, +0.86, +0.88, +0.89 and +0.88 V vs. SCE for AN-1, AN-3, AN-5, AN-7 and AN-8, respectively. For the reductions (Figure 3b), the ill-shaped redox couples found around 0.70 V vs. SCE are consistent with the reduction of the anchoring group.40 Further into the more negativepotential region, all AN-x dyes exhibited a quasireversible reactions at -1.42, -1.43, -1.38, -1.33 and -1.33 V vs. SCE for AN-1, AN-3, AN-5, AN-7 and AN-8, respectively. As expected, the reduction potential of AN-3 is very similar to that of AN-1. For AN-5, AN-7 and AN-8, the reduction potentials are positively shifted from those of AN-1 or

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a

Table 1. Spectral and Electrochemical properties of the AN-x dyes. Absorption/nm Dye

-1

-1

Emission/nm

(log, M cm )

E/V vs. SCE

b

Ox

c

Red

d

o

+

S /S (eV)

e

E0-0

S*(eV)

AN-1

491 (4.61)

600

+0.86

-1.42

-5.60

2.31

-3.29

AN-3

499 (4.69)

603

+0.86

-1.43

-5.60

2.28

-3.32

AN-5

500 (4.63)

613

+0.88

-1.38

-5.62

2.25

-3.37

AN-7

503 (4.57)

613

+0.89

-1.33

-5.63

2.25

-3.38

AN-8

509 (4.64)

615

+0.88

-1.33

-5.62

2.21

-3.46

a

Electrochemical measurements were carried out at 25 °C with each sample (0.5 mM) in THF/0.1 M b TBAP/N2, Pt working and counter electrodes, an SCE reference electrode, scan rate = 100 mV/s. [AN-x] = c 2×10−6 M in THF. Excitation wavelength/nm: AN-1, 491; AN-3, 499; AN-5, 500; AN-7, 503; AN-8, 509. Pod tentials estimated by differential pulse voltammetry due to less reversible oxidation waves. Potentials e o + o + obtained by cyclic voltammetry. S /S values were estimated from the first oxidation potentials, S* = S /S + E0−0. E0−0 values were determined by the intersection of normalized UV−visible and fluorescent spectra.

Figure 4. Energy levels of AN-x , TiO2 conduction bands, and the electrolyte.

AN-3 likely due to the additional electron-withdrawing groups. Unlike other AN-x dyes, however, an additional and irreversible reduction can be observed for AN-7 around -1.55 V vs. SCE.

Figure 3. Cyclic voltammograms of 0.5 mM of AN-x in THF/0.1 M TBAP (a) oxidations and (b) reductions.

Energy levels and MOs Figure 4 compares the energy levels of the ground to oxidized state (So/S+), the first singlet excited state (S*) of each AN-x, the conduction bands (CB) of TiO2 and the redox potential of the electrolyte (I/I3-). The So/S+ levels of AN-x were estimated from their first oxidation potentials. The zero-zero excitation energies (E0-0) of the AN-x dyes were obtained from the interceptions of the corresponding normalized absorption and emission spectra record in THF. The energy levels of the

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S* states were generated by subtracting E0-0 from So/S+. As shown in the diagram, the So/S+ states of AN-x are all considerably lower than the electrolyte level, whereas the S* states of AN-x are all much higher than the conduction band of TiO2. This suggests that the AN-x dyes should all be capable of injecting electrons to the TiO2 upon excitation and be regenerated by the electrolyte. To assist our qualitative understanding to the frontier molecular orbitals of the AN-x dyes, we performed DFT calculations at the B3LYP/6-31G(d,p) level of theory.41 As shown in Figure 5, the electron densities of all AN-x at the HOMO levels reside mainly at the donor and the anthryl parts. In contrast, the electron probabilities at the LUMOs fairly localize at the anchoring and the anthryl units. As such, the frontier MO patterns suggest a good pushpull tendency for AN-x upon excitation, a merit for n-type DSC applications.

Photovoltaic properties Figures 6a and 6b show the corresponding current-voltage characteristics and the IPCE action spectra of small-cell DSCs using AN-x. The photovoltaic parameters are summarized in Table 2. As shown in these results, the AN-3 cell outperforms others in the series with a PCE of 5.90 %. This should be attributed to the stronger Jsc, the highest Voc, and the best FF values. For Jsc, the AN-x small cells showed a trend of AN-8 > AN-5 > AN-3 > AN-1 > AN-7. This trend is consistent with the IPCE spectra (Figure 6b and JscEQE in Table 2). The greater Jsc value of the AN-8 cell is consistent with the broadened UV-visible and IPCE spectra of the dye. In addition, the Jsc values of the AN-3 and AN-5 cells are greater than that of the AN-1 device, consistent with their slightly stronger and red-shifted IPCE responses. For AN7, the much lower Jsc may be related to the instability of the DSCs. During the photovoltaic measurements, we noticed that the AN-7 cell ceased to convert solar energy upon excitation in a matter of minutes. For Voc, the AN-x cells show a trend of AN-3 > AN-5 > AN-1 > AN-8 > AN-7. The higher Voc value of the AN-3 device than that of the AN-1 cell may be attributed to the hydrophobic octyl chains. For the AN-5, AN-7 and AN-8 devices, the lower Voc values may be related to the additional electron-withdrawing groups at the anchors. For the AN-8 device, the Voc value is considerably lower than that of the AN-3 cell, showing the difference in the anchoring groups (i.e. cyanoacrylic acid vs. benzoic acid). For AN-7, the Voc value of the DSC is the lowest in the series. This behavior is different from those of other nitrobearing organic dyes reported in the literature by Sun's42 and Han's43 groups.

Figure 5. HOMO and LUMO patterns of AN-x by DFT at B3LYP/6-31G (d,p). 2 a

Table 2. Photovoltaic properties of AN-x under simulated AM 1.5 irradiation (100 mW/cm ).

Dye

EQE

Jsc

2 b

(mA/cm )

Dye-loading

2

Jsc(mA/cm )

Voc (V)

FF

η(%)

2

(nmol/cm ) AN-1

9.23

10.10±0.40

0.71±0.02

0.75±0.01

5.36±0.05

238.02

AN-3

9.49

10.66±0.20

0.73±0.01

0.76±0.01

5.90±0.06

196.43

AN-5

9.99

10.77±0.02

0.72±0.00

0.75±0.01

5.78±0.04

214.49

AN-7

2.47

1.80±0.12

0.56±0.00

0.73±0.01

0.74±0.05

243.10

AN-8

12.19

13.04±0.02

0.61±0.00

0.71±0.00

5.59±0.00

193.99.

a

2

All TiO2 working electrodes were fabricated under the same experimental conditions. The active area was 0.25 cm with a 2 b black mask of area 0.16 cm . The values of each parameter are the averaged number of four independent devices. To compare EQE with the JSC obtained from the J-V measurements, JSC is derived via wavelength integration of the IPCE spectra.

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Figure 7. Photovoltaic parameters of AN-3 under the ambient conditions for 2000 hours.

Because of its better performance, we monitored the long-term stability of the AN-3 devices under ambient conditions (at room temperature and under in-door lights). As shown in Figure 7, the overall efficiency of the AN-3 cell dropped only 3% after 2000 hours, showcasing the potentials of AN-3 for indoor applications. To further our studies, we measured the photovoltaic properties of the AN-3 modules with a larger area under indoor conditions.

Figure 6. (a) J-V curves and (b) IPCE spectra of the AN-x devices.

AN-3- and Z707-sensitized DSC modules were fabricated by Taiwan DSC PV Ltd. (or TDP, see Figure S2 for the picture). The active area of the modules were 36 cm2, and a iodide-based gel was used as the electrolyte. In addition to AM 1.5 (100 mW/cm2), three artificial light sources, including the T5, T8 and LED fluorescent lights at 200, 600, and 100 Lux, were used to study the AN-3 2

Table 3. Photovoltaic properties of AN-3 and Z907 modules under simulated AM 1.5 (100 mW/cm ) and various artificial light a sources at 1000 Lux. Light source

Light intensity (mW/cm2)

Simulated AM 1.5 G

100

T5

0.336

T8

LED

0.338

0.313

2

Dye

Jsc(mA/cm )

Voc (V)

FF

Pmax (mW)

η (%)

AN-3

7.03±0.12

0.64±0.00

0.49±0.12

77.2±3.40

2.25±0.05

Z907

10.76±0.21

0.61±0.00

0.63±0.00

145.4±7.17

4.11±0.01

AN-3

0.06±0.00

0.46±0.00

0.67±0.00

0.66±0.01

5.45±0.09

Z907

0.06±0.00

0.46±0.00

0.69±0.03

0.69±0.05

5.67±0.20

AN-3

0.06±0.00

0.43±0.00

0.63±0.00

0.59±0.01

4.85±0.09

Z907

0.05±0.00

0.46±0.00

0.68±0.04

0.61±0.06

4.99±0.50

AN-3

0.05±0.00

0.45±0.00

0.66±0.00

0.56±0.01

4.94±0.11

Z907

0.05±0.00

0.46±0.00

0.68±0.01

0.57±0.04

5.05±0.33

a

2

All modules were fabricated under the same experimental conditions by TDP. Active area is 36 cm . Each and every parameter is the averaged values of four different modules.

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The AN-3 small cell also exhibited good long-term stability under ambient conditions. Under T5 fluorescent light at 1000 Lux, the AN-3 module (area: 36 cm2) exhibit PCE of 5.45 %, which is comparable with that of the Z907 module under the same condition. We also optimized the synthetic procedures of AN-3 to achieve gram-scale production cost of U.S. 65/g.

AUTHOR INFORMATION Corresponding Author

Figure 8. The UV-Visible absorption spectrum of AN-3 and the emission spectra of T5, T8 and LED fluorescent lights.

modules. Photovoltaic parameters of the AN-3 modules under simulated AM 1.5 and T5 fluorescent light (1000 Lux) irradiation are collected in Table 3. The parameters of Z907 modules are also tabulated for comparison. Photovoltaic characters of AN-3 modules under various light sources at 600 and 200 Lux are collected in Table S2 and S3, respectively. Figure 8 compares the absorption spectrum of AN-3 with the emission wavelengths of T5, T8 and LED fluorescent lights. Under simulated AM 1.5 irradiation (100 mW/cm2), the AN-3 and Z907 modules gave rise to PCE of 2.25 % and 4.11 %, respectively. The Z907 module obviously outperforms the AN-3 module. The better efficiency of the Z907 reference cell should result from superior Jsc and FF values. Although the AN-3 module exhibits slightly lower Jsc and considerably higher Voc, the FF value is much poorer than that of the Z907 cell, resulting in a poorer overall efficiency. Under the dim-light conditions, however, the overall efficiencies of the AN-3 and Z907 modules are very similar. As expected, the Jsc and Voc values of both modules largely decreased under the dim-light conditions. Importantly, the photovoltaic performance of the AN-3 module is comparable to that of the Z907 module under dim-light conditions. Impressively, the AN-3 module achieves PCE of 5.45 % under T5 fluorescent light at 1000 Lux. Interestingly, both the AN-3 and Z907 modules perform better under the T5 irradiation. This might be related to the different emission spectra of the artificial light sources (Figure 8).

* To whom correspondence should be addressed. a Department of Applied Chemistry, National Chi Nan University, No. 302 University Road, Puli, Nantou Hsien 54561, Taiwan (R.O.C.). Fax: +886-49-2917956; Tel: +886-492910960 ext. 4152; E-mail: [email protected] b Taiwan DSC PV Ltd., No. 7, Minquan Rd., Dayuan Dist., Taoyuan City 33759, Taiwan (R.O.C.). Fax:+886-3-3869207; Tel:+886-3-3861646; E-mail: [email protected]

ACKNOWLEDGMENT This work is supported by the Ministry of Science and Technology, Taiwan (MOST 103-2119-M-260-001 and NSC 102-2113M-260-003-MY3).

ASSOCIATED CONTENT Supporting Information. Dye synthesis & characterization, normalized absorption spectra of AN dyes in THF and on TiO2 films, pictures of a small DSC cell and the larger modules, and photovoltaic properties of AN-3 and Z907 modules under various fluorescent lights at 600 Lux. This information is available free of charge via the Internet at http://pubs.acs.org

ABBREVIATIONS DSC, dye-sensitized cell; PCE, power conversion efficiency; IPCE, incident photon-to-electron conversion efficiency.

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Conclusion

In this work, a series of anthrance-based organic dyes were prepared to evaluate the photovoltaic performance of the DSCs under one sun and dim-light conditions. Under one sun irradiation, the AN-3 small cell (area: 0.16 cm2) outperforms other AN-x DSCs with a PCE of 5.90 %.

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SYNOPSIS TOC

A cost-effective anthryl dye shows efficient photovoltaic performance under dim-light conditions.

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