Structurally Simple and Easily Accessible Perylenes for Dye

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Structurally Simple and Easily Accessible Perylenes for Dye-sensitized Solar Cells Applicable to Both One Sun and Dim-light Environments Hsien-Hsin Chou, Yu-Chieh Liu, Guanjie Fang, Qiao-Kai Cao, Tzu-Chien Wei, and Chen-Yu Yeh ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.7b11784 • Publication Date (Web): 09 Oct 2017 Downloaded from http://pubs.acs.org on October 10, 2017

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ACS Applied Materials & Interfaces

Structurally Simple and Easily Accessible Perylenes for Dye-sensitized Solar Cells Applicable to Both One Sun and Dim-light Environments Hsien-Hsin Chou,†,§ Yu-Chieh Liu,‡,§ Guanjie Fang,† Qiao-Kai Cao,‡ Tzu-Chien Wei*,‡ and Chen-Yu Yeh*,† †Department of Chemistry and Research Center for Sustainable Energy & Nanotechnology, National Chung Hsing University, Taichung 402, Taiwan ‡Department of Chemical Engineering, National Tsing Hua University, Hsinchu 300, Taiwan

Keywords: charge transfer, dim light, dye, perylene, solar cells

ABSTRACT. The need for low-cost and highly efficient dyes for dye-sensitized solar cells under both the sunlight and dim light environments is growing. We have devised GJ-series push-pull organic dyes which require only four synthetic steps. These dyes feature a linear molecular structure of donor-perylene-ethynylene-arylcarboxylic acid where donor represents N,Ndiarylamino group and arylcarboxylic groups represents benzoic, thienocarboxylic, 2-cyano-3-

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phenylacrylic, 2-cyano-3-thienoacrylic and 4-benzo[c][1,2,5]thiadiazol-4-yl-benzoic groups. In this study, we demonstrated that a dye without tedious and time-consuming synthetic efforts can perform efficiently. Under the illumination of AM1.5G simulated sunlight, the benzothiadiazolebenzoic-containing GJ-BP dye shows the best power conversion efficiency (PCE) of 6.16% with VOC of 0.70 V, JSC of 11.88 mA cm-2 using liquid iodide-based electrolyte. It also shows high performance in converting light of 6,000 lux light intensity, that is, incident power of ca. 1.75 mW cm-2, to power output of 0.28 mW cm-2 which equals to PCE of 15.79%. Interestingly, the benzoic-containing dye GJ-P with a simple molecular structure has comparable performance in generating power output of 0.26 mW cm-2 (PCE of 15.01%) under the same condition and is potentially viable toward future application.

INTRODUCTION Dye-sensitized solar cells (DSCs) have attracted considerable research interest over the past two decades and have been considered an attractive alternative to conventional silicon-based photovoltaics.1-2 On the way toward practical application of DSC technology, the concept of energy recycling under dim indoor light conditions has been proposed. Unlike silicon-based photovoltaics, DSCs are weakly dependent on the angle of incident light and performs much better under low light conditions,3 making them suitable light-harvesting devices for the integration with sensors, wireless transmitters in the internet of things (IoTs) system. These features strongly indicate plausible dim light application of DSCs since the living environment of human beings is predominately surrounded by T5 fluorescent lamps and white LED lights. However, the emission spectra of commercial T5 fluorescent light, unlike panchromatic


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irradiance of sunlight, mainly covers the visible region from 400 to 640 nm including three major peaks at ca. 430, 550 and 620 nm. Thanks to the flexibility of dye design and tunable spectra response, one can fabricate a single dye-sensitized cell which exhibits high conversion efficiencies under both sunlight and artificial light environments.4-8 It should be noted that there is a huge difference on the intensity between sunlight (typically >100,000 lux outdoor at daytime) and dim lights (usually ranging between 300–6,000 lux depending on indoor environments). For example, a 10%-PCE cell will convert 600-lux light with incident power of ca. 0.176 mW cm-2 to power output of ca. 17.6 µW cm-2, and a 5%-PCE cell generates ca. 8.8 µW cm-2 of power. Both cases, with the help of voltage booster, would be satisfactory to drive common microelectronics having power consumption range at microwatt-scale. Nevertheless, a 10%-PCE cell with much higher fabrication costs than that of 5%-PCE cell would probably lose competitiveness under the circumstance that requires the dye materials to be efficient enough and of low-cost. Therefore, smart devising of highly efficient and structurally simple dyes is important since the most vital component in a DSC is the dye which sensitizes the semiconductor via absorbing incident photons and generates photoelectrons. In the past few years, a number of state-of-the-art photosensitizers with PCE of >10% under simulative AM1.5 conditions have been reported for the categories of ruthenium complexes,9-10 porphyrin-based dyes11-17 and metal-free organic dyes.18-21 Despite the fruitful results on the investigation of ruthenium- and porphyrin-based dyes, organic dyes can be accessed in large scale because of relatively low cost of raw materials and design flexibility. In general, typical high efficiency organic dyes consist of D-π-A molecular structure where D and A refer to electron-donor and acceptor, respectively,20 although some recent studies have unveiled the


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possibility to abandon usage of the strong donor and/or acceptor groups in dye structure without losing performance.22-27 As one of polycyclic aromatic hydrocarbons (PAHs), perylenes have been widely studied for its intense light-absorption at UV-vis region, strong fluorescence quantum yield, chemical stability and structural tunability which allows for promising optoelectronic applications.28-29 Therefore, dyes based on perylene anhydride (PA) or perylene monoimide (PMI) for DSCs have been reported.30-35 Solar cells sensitized by these dyes have PCEs from 0.6 V and matching of light-absorption spectrum with the emission of artificial light sources. Encouraged from these exciting results, we step forward to devise push-pull organic dyes with enhanced light-harvesting properties and remains structurally simple in order to find out the balance between cost efficiency and best spectral response under both light sources. Herein we report a series of new dyes with perylene moiety28 as the chromophore. Unlike the reported NP- and PAH-based dyes, we have devised a practical protocol to access dye synthesis within four synthetic steps while remain good performance for the corresponding DSCs under both One Sun and dim light conditions.

RESULTS AND DISCUSSION


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Synthesis and characterizations It has been reported that direct dibromination of perylene gives a mixture of 3,9- and 3,10dibromoperylene with low yields and isolation of both products requires tedious purification processes.57 We developed a stepwise route that are simple and practical for the preparation of 3,10-disubstituted push-pull perylenes. With this protocol, namely single bromination-aminationsingle bromination, the perylene can be functionalized easily at 3,10-position owing to strong directing effect of the amine group at 3-position. Based on this approach, new perylene sensitizers were designed and synthesized in good to moderate yields starting from 3bromoperylene (1), as shown in Scheme 1. The 3-diarylaminoperylene (2) is synthesized via Buckwald-Hartwig coupling of 1 with N,N-diarylamine.58-59 Bromination of perylene 2 occurs selectively at the 10-position leading to a single product as 10-bromo-3-diarylaminoperylene (3) isolated in 86% yield (Scheme 1). Perylene 3 is then reacted with triisopropylsilyl acetylene (TIPSA) under palladium-catalyzed Sonogashira coupling60 conditions to give corresponding perylene 5 in 88% yield. Structural determination of 5 via 1D and 2D NMR techniques confirmed the 3,10-disubstituted architecture of perylene which offers strong evidence that mono-bromination of 2 leads to formation of 3 instead of 4. The 1H NMR spectrum of 5 shows the doublets at 6.76 and 6.95 ppm correspond to aromatic protons of N-alkoxyphenyl groups, and the resonance peaks Ha–Hj at ca. 7.2–8.3 ppm are assigned to aromatic protons on perylene with the most up-field peak corresponding to the proton Ha α to nitrogen atom (Figure S1 in supporting information). 2D NMR 1H-1H correlation spectroscopy (COSY) shows two sets of off-diagonal cross-peaks, one containing Ha and Hg and another containing Hd and Hf, representing 3J coupling between Ha and Hg as well as that between Hd and Hf (Figure 1a). Two sets of mutually correlated cross-peaks, each set containing one triplet and two doublets


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(resonances Hb, He and Hh; resonances Hc, Hi and Hj) were also found, as shown in Figure S2. Excitation of the resonance peak Hg at 8.05 ppm in one-dimensional rotating-frame nuclear Overhauser effect (1D ROESY) experiment leads to spin-spin relaxation to nearby protons in space, that is, the resonance peak Ha at 7.15 ppm and peak Hf at 7.97 ppm (see Figure 1b). Since resonance peaks Hg and Ha refer to protons at perylene 1- and 2-position, respectively, the peak Hf is thus identified as proton at 12-position of perylene. In the opposite, according to the molecular structure of 6, Hk would couple to a triplet Hl, which was not observed in 2D NMR spectra. The results clearly suggest a molecular structure of 5 instead of 6 (Figure 1b). Therefore, the bromination of 3 was confirmed to selectively occur at 10-position. We then functionalized 5 with a series of arylcarboxylic acid as the anchor for TiO2 semiconductor. The TIPS group on 5 was removed by fluoride to provide the corresponding terminal alkyne which underwent palladium catalyzed Sonogashira coupling with the corresponding iodide to give dyes GJ-x (x = P, T, PC, TC or BP representing benzoic, thieno carboxylic, 2-cyano-3-phenylacrylic, 2-cyano3- thienoacrylic or 4-benzo[c][1,2,5]thiadiazol-4-yl-benzoic groups, respectively) in 18–65% (Scheme 2).

Photophysical and electrochemical properties Compound 5 is soluble in most organic solvents due to the presence of branched aliphatic chains. It exhibits non-localized π-π* transition at 495 nm (ε = 3.26 × 104 M-1 cm-1) upon photoexcitation (gray line in Figure 2a). The absorption of GJ dyes shows broad peaks covering the UV-vis region from 400 nm to ca. 650 nm with extinction coefficient ranging at 3.54–4.75 × 104 M-1 cm-1 (see Table 1, Table S1 in Supporting Informaiton and Figure 2a, thick lines with open circle). It is worth noting that the emitting profile of T5 fluorescent light has three major peaks


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at ca. 430, 540 and 610 nm (shaded yellow lines in Figure 2c), quite matching the absorption spectra of GJ/TiO2 films (Figure 2b). The absorption maxima (λabs) for GJ-series dyes either in solution or as thin film were characterized with significant charge-transfer behavior and were correlated with electron-withdrawing ability of the attached acceptor groups. The benzothiadiazole and 2-cyanoacrylic entities cause red-shift absorption λmax of GJ-BP/GJPC/GJ-TC relative to the other dyes, and the 2,5-bridged thieno group better facilitates the electronic communication of GJ-T/GJ-TC compared to the 1,4-bridged phenyl moiety in GJP/GJ-PC.61 Consequently, the λmax of dyes in THF solution with a trend of GJ-TC (545 nm) ~ GJ-BP (541 nm) > GJ-PC (528 nm) ~ GJ-T (525 nm) > GJ-P (520 nm) > 5 (495 nm) is observed (Table 1). The improvement of light-harvesting for perylene-based dyes is observed when comparing GJ-BP (541 nm) with cyclopentadithiophene (SC-1,44 525 nm) and anthracene (TY4,4 532 nm) analogues. Similar behavior is also observed when comparing GJ-P (520 nm) and TY34 (504 nm). Note the N-annulated perylene dye C289 has red-shifted λmax at 550 nm in a relative nonpolar solvent compared to GP-BP.45 The absorption for GJ-series dyes is broadened after adsorbed on TiO2 thin film, which becomes significant if the acceptor is benzoic (GJ-P) or 4-benzo[c][1,2,5]thiadiazol-4-yl-benzoic group (GJ-BP) (Figure 2b). It is found that the excitedstate potentials (E0-0*) calculated from oxidation potential and optical gandgap can be tuned with terminal electron-withdrawing groups: GJ-BP (-1.25 V) ~ GJ-TC (-1.25 V) < GJ-PC (-1.31 V) ~ GJ-T (-1.33 V) ~ GJ-P (-1.34 V) (Table 1 and Figure S3 in Supporting Information). Although this energy level alteration can influence charge injection, it is believed that the kinetically slower recombination processes appear to influence the overall efficiency,10, 62 which can be controlled by dye molecular design, as illustrated in the following section. On the other hand, the oxidation potential of the dyes that occurs primarily at electron-donating 3-(N,N-


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diarylamino)perylene group are around 0.18 V cathodically shifted compared to the anthracenebased TY-series analogues4 and are essentially not affected by electron-withdrawing groups at a distance away. After calibrated with Fc/Fc+ as the reference, GJ-BP has higher oxidation potential (+0.15 V) compared to that of N-annulated derivative C28945 (+0.02 V) and PAH analogue R163 (+0.09 V). Nevertheless, the E1/2ox in our system ensures more than 0.2 V of free energy for charge regeneration mediated by higher lying I–/I3– electrolytes.64 Apart from this, it is considered that the spectral coverage of absorption and intermolecular interactions caused by implanted π-conjugating aryl groups will dominate the performance of perylene-sensitized solar cells.

Photovoltaic performances These perylene dyes were used as photosensitizers for TiO2 DSC employing I–/I3– electrolytes in the presence of CDCA co-adsorbent. The J-V plots and incident photon-to-current conversion efficiency (IPCE) spectra are shown in Figure 3 and Figure S4; Table 2 displays the corresponding averaged J-V parameters. Note that for all cells the TiO2 active area is 0.16 cm2 (0.4 cm × 0.4 cm in dimension), this is covered by shading mask with area of either 0.14 cm2 (0.38 cm × 0.38 cm in dimension) or 0.36 cm2 (0.6 cm × 0.6 cm in dimension) upon I-V measurements. No shading mask is used for IPCE measurement where the irradiation spot of 0.3 cm in diameter of light source is employed (detailed in Supporting Information). As a result, a ca. 30 mV higher open-circuit voltage (VOC) were observed for GJ-P and GJ-BP devices with VOC = 0.66–0.68 V compared to those with other acid terminals, e.g., GJ-T, GJ-PC and GJ-TC with 0.63–0.65 V (Figure 3a). The measured short-circuit currents (JSC) shows a trend of GJ-BP (12.46 ± 0.55 mA cm-2) > GJ-TC (11.20 ± 0.13 mA cm-2) ~ GJ-P (10.55 ± 0.47 mA cm-2) > GJ-


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T (10.08 ± 0.39 mA cm-2) ~ GJ-PC (9.96 ± 0.34 mA cm-2), leading to efficiencies (η) of GJ-BP (6.00 ± 0.10%) > GJ-TC (5.21 ± 0.23%) ~ GJ-P (5.19 ± 0.06%) > GJ-T (4.76 ± 0.12%) ~ GJPC (4.48 ± 0.12%), when shading mask of 0.14 cm2 area is employed. The same trend is observed for those using larger shelding mask of 0.36 cm2, indicating the independence of given measuring condition (Table S3 in Supporting Information). The relative large variation in JSC reflects on IPCE where GJ-T and GJ-PC have the smallest coverage in the UV-vis region (Figure 3b). In comparison, devices with GJ-TC and GJ-P exhibit improved performances in terms of either broadened IPCE spectra or higher EQE. Eventually, the GJ-BP-based cell has both higher IPCE values and broader spectrum coverage which are responsible for the best cell performance. It is obvious that the IPCE coverage of perylene-based devices is closely related to the dye absorption on TiO2 thin-film (Figure 2b). In addition to photocurrents, the VOC is also responsible for the conversion efficiency, which is closely related to the conduction band edge of surface of TiO2 and can be easily evaluated by trapped continuum model.65 Accordingly, we proceeded to scrutinize the internal characteristics of devices employing the electrochemical impedance spectroscopy (EIS). The devices were probed with bias voltage in the range 0.475– 0.575 V in the dark, and the deducible data were fitted with transmission-lined model.66 The fitted results were given in Figure 4 demonstrating linear relationships of interfacial charge recombination resistances (Rct), chemical capacitances (Cµ) and electron lifetimes (τ0) plotted on a logarithmic scale versus applied bias voltage. The results gave us a clearer picture of structureproperty relationship between terminal functional group of the dye molecule and device performances. In Figure 4a and 4b, it is seen that the GJ-BP-based device has the largest Rct and smallest Cµ than all the others. Calculated electron lifetimes76,77 (τ0) for these dyes according to the formula τ0 = Rct·Cµ are at the magnitude of 10-1 sec and has a trend of GJ-BP ~ GJ-P > GJ-


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TC ~ GJ-PC > GJ-T (Figure 4c), indicating a similar trend of TiO2 conduction band edge from higher lying GJ-BP/GJ-P to intermediate and lower lying GJ-TC/GJ-PC/GJ-T. In Figure 4b, the significant distribution of chemical capacitance over three separate lines is consistent with charge density in the order of GJ-PC > GJ-T ~ GJ-P ~ GJ-TC > GJ-BP. This phenomenon in some extent correlates to the JSC of corresponding devices in the trend: GJ-PC ~ GJ-T < GJ-P ~ GJ-TC < GJ-BP (Figure 3a). In addition, the ca. 20–25 mV difference in voltage between GJBP and others devices might also contribute to the higher VOC of the former. Interestingly, dyes GJ-BP and GJ-P with benzoic acid terminal end up with larger τ0 for the corresponding DSC devices, despite of their dramatic difference in intramolecular electronic influences and charge transfer characteristics (Figure 2a). The higher alignment of energy level at the interface in the cases of GJ-BP/GJ-P are presumably altered by larger surface dipole potential67 because of the linear and rigid molecular geometry (Figure 5). Moreover, we speculate that the geometry will cause larger τ0 of GJ-BP/GJ-P which enhances ordered molecular layer and optimized CDCA coverage on TiO2 surface. This is beneficial to more suppressed charge recombination on TiO2/electrolyte interfaces and is evident in Figure 4a showing relatively higher Rct of GJBP/GJ-P cells. Both of the factors in combination eventually contribute to higher VOC. On the other hand, dyes with terminal cyanoacrylic acid group have more geometrical flexibility which would be difficult to form an ordered molecular layer on TiO2 surface. This is considered to increase the possibility for iodide-based electrolytes to penetrate through dye monolayer and to approach TiO2 surface, as illustrated in Figure 5. Eventually, DSC fabricated with GJ-BP dye has best conversion efficiency of 6.16% under the illumination of AM1.5G simulated sunlight, owing to higher VOC (0.70 V) and JSC (11.88 mA cm-2) that compensate for slightly lower fill factor (0.74) (see also Table S2 in Supporting Information). Compared to the similar


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performance of reported C289 having N-annulated perylene backbone (VOC = 0.74 V; JSC = 12.8 mA cm-2; FF = 0.74; PCE = 7.0%),45 our dye GJ-BP would probably be more cost-efficient because of its facile synthesis and comparable device performance.

DSC performance under dim light conditions We further studied the photovoltaic performance application of perylene-sensitized solar cells under dim light environments. Both T5 fluorescent lamp and white LED light were chosen to illuminate the DSCs with controlled intensity of 300–6,000 lux. Selected results for the two best performing devices GJ-BP and GJ-P are illustrated in Figure 6 and summarized in Table S4, the detailed are given in Figure S5-S7. Figure 6a demonstrates a huge boost of conversion efficiency for GJ-BP devices when replacing simulated One-Sun light (ca. 6%) with T5 and LED artificial lights (ca. 9–16%). This is rationalized with different emission profile between sunlight and artificial lights,4-5 where the light harvesting properties of dyes better match the latter. As shown in Figure 6b, both the JSC, VOC and output power (Pmax) for these devices increased in a linear relationship with the light intensity. Among these perylene dyes, GJ-BP shows the best performance under varied dim light intensities. The best performing device of GJ-BP under 6,000-lux light (1.75 mW cm-2) using T5 fluorescent lamp exhibits JSC of 6.40 mA cm-2, VOC of 0.57 V, FF of 0.76 and Pmax of 0.28 mW, giving a PCE of 15.79%. Interestingly, the GJ-P cells also exhibit promising performance with JSC of 5.94 mA cm-2, VOC of 0.60V and Pmax of 0.26 mW, giving to a conversion efficiency of 15.01%. The efficiency ratio of 1.05 for GJ-BP/GJ-P is substantially reduced compared to that under 1 Sun condition (ratio = 1.16). Considering the additional synthetic complexity and cost68 for benzothiadiazole-containing dye GJ-BP, the more


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rigid, robust and inexpensive GJ-P dye would probably be the most viable dye for mass production for future indoor application. It is noted that solar cells sensitized with GJ-series dyes possess reasonable stability under dim light conditions. As shown in Figure 7 and Figure S9, after aging test for 6,000 hours at programmed temperature range from ca. 25 to 40 oC, the best performing GJ-BP device has PCE decays from 6.30% to 4.96% using AN-based liquid electrolyte. This considerable efficiency loss of >20% comes from high volatility of AN which causes higher concentration of I3– and favors charge recombination. However, only an 8% efficiency loss is obtained if low-volatile MPN-based electrolyte is used, and the PCE decreases from 5.60% to 5.14%.

CONCLUSIONS In summary, we have demonstrated facile functionalization of perylenes at 10-position using the directing effect of diarylamino group at 3-position. This easy approach has allowed us to prepare push-pull organic dyes GJ-x (x = P, T, PC, TC or BP). The dye synthesis simply involves four steps using Buchwald-Hartwig C-N coupling, Sonogashira cross-coupling and bromination reaction starting from 3-bromoperylene. The GJ-series dyes adopt a donorperylene-ethynylene-acceptor type of linear molecular structure where donor and acceptor represent N,N-diarylamine and arylcarboxylic acid, respectively. These perylene-based dyes exhibit good light-harvesting and suitable spectra that match well with LED and T5 lights. The structurally simpler benzoic derivative GJ-P has smaller PCE of 5.29% under the same condition. However, when T5 fluorescent lamp with light intensity of 6,000 lux (ca. 1.75 mW cm-2) is used as light source, both GJ-BP and GJ-P performs as high as 15.79% (power output of 276 µW cm-2) and 15.01% (power output of 263 µW cm-2), respectively. These results


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strongly indicate potential indoor applications of DSCs using perylene dyes, especially for the more cost-efficient benzothiadiazole-free dye (GJ-P). It should be noted that the structurally similar perylene dyes such as C272,41 HW-343 and C28846 appear to have better cell performance. However, the tedious synthetic procedures would limit the practical application of these dyes. On other hand, our work on simple functionalized perylene dyes has undoubtedly provided an example for practical application in promising performances for corresponding dyesensitized solar cells both under simulated One Sun or dim light environment. Among these dyes, the dye GJ-BP implanted with benzothiadiazole π-linker adjacent to benzoic acid acceptor/anchor shows best conversion efficiency of 6.16% with JSC of 11.88 mA cm-2 and VOC of 0.697 V under One Sun condition, ascribed to its superior light-harvesting property, suitable HOMO level and presumably ordered dye molecular the future.

EXPERIMENTAL General information All reagents and solvents were obtained from commercial sources and used without further purification unless otherwise noted. CH2Cl2 was dried over CaH2 and freshly distilled before use. THF was dried over sodium/benzophenone ketyl and freshly distilled prior to use. Tetra(nbutyl)ammonium hexafluorophosphate ([(n-Bu)4N]PF6) was recrystallized twice from absolute ethanol and further dried for two days under vacuum. Column chromatography was performed on silica gel (Merck, 70-230 Mesh ASTM). 1H NMR spectra were acquired on Varian spectrometer operating at 400 MHz.

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C NMR spectra were acquired on Varian spectrometer

operating at 101 MHz or 151 MHz. The UV-visible absorption and emission spectra were measured at Varian Cary 50 spectrophotometer and JASCO FP-6000 spectrofluorometer,


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respectively. FAB-MS mass spectra were recorded on Bruker APEX II spectrometer operating in the positive ion detection mode). Electrochemical tests were performed on CH Instruments 750A potentiostat using deoxygenated THF as solvent. A standard cyclic voltammetric (CV) experiments based on three-electrode system is conducted. The working electrode uses BAS glassy carbon (0.07 cm2) disk, while the reference and auxiliary electrodes used Ag/AgCl (saturated) and platinum wire, respectively. Potentials are reported with reference to ferrocene/ferrocenium (Fc/Fc+) couple at E1/2 = +0.44 V at 23 oC in CH2Cl2. The working electrode was polished with 0.03 µm aluminium on felt pads (Buehler) and treated ultrasonically for 1 min before each experiment. The reproducibility of individual potential values was within ±5 mV.

Synthesis N,N-bis(4-((2-butyloctyl)oxy)phenyl)perylen-3-amine

(2).

At

nitrogen

atmosphere

3-

bromoperylene (1) (0.60 g, 1.81 mmol), bis(dibenzylideneacetone)palladium(0) (0.083 g, 0.09 mmol), NaO(t-Bu) (0.52 g, 5.43 mmol) were weighted into Schleck flask. A 80 mL toluene solution containing P(t-Bu)3 (0.09 g, 0.45 mmol) and bis(4-((2-butyloctyl)oxy)phenyl)amine (1.46 g, 2.71 mmol) was syringed into the flask. The resulting solution was subsequently heated at 125 oC for 12 hours. After that, volatiles were removed under reduced pressure. The resulting residues were purified by column chromatography using silica gel (hexanes/CH2Cl2: 8/1 v/v as eluent) to give 2 as red oily product (0.84 g, 58%). ESI-MS (m/z) calcd for C56H69O2N: 787.53; Found: 788.5 [M+H]+. 1H NMR (CDCl3, 400 MHz): δ 8.18–8.10 (m, 4H), 7.86 (d, J = 8.4 Hz, 1H), 7.67 (t, J = 8.5 Hz, 2H), 7.47 (td, J = 7.8, 2.7 Hz, 2H), 7.34 (t, J = 8.0 Hz, 1H), 7.21 (d, J = 8.0 Hz, 1H), 6.97 (d, J = 8.8 Hz, 4H), 6.78 (d, J = 8.8 Hz, 4H), 3.79 (d, J = 5.6 Hz, 4H), 1.79–


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1.71 (m, 2H), 1.50–1.30 (m, 32H), 0.93–0.88 (m, 12H). 13C NMR (CDCl3, 100 MHz): δ 154.6, 144.6, 142.4, 134.7, 131.6, 131.3, 131.2, 130.3, 128.4, 128.1, 127.8, 127.3, 126.6, 126.6, 126.5, 126.2, 124.6, 123.6, 120.9, 120.5, 120.1, 119.8, 115.1, 71.2, 38.0, 31.9, 31.4, 31.1, 29.7, 29.1, 26.8, 23.1, 22.7, 14.1. N,N-bis(4-((2-butyloctyl)oxy)phenyl)-10-((triisopropylsilyl)ethynyl)perylen-3-amine

(5).

At

nitrogen atmosphere, a CH2Cl2 solution (50 mL) containing N-bromosuccinimide (0.20 g, 1.12 mmol) was added dropwise into a CH2Cl2 solution (190 mL) of compound 2 (0.80 g, 1.02 mmol) at 0 oC. The reaction was monitored by TLC. After that, acetone was added to the solution to terminate the reaction. Volatiles were removed and the resulting residues were purified by column chromatography using silica gel (hexanes/CH2Cl2: 9/1 v/v as eluent) to give red oily product 3 (0.76 g, 86%). ESI-MS (m/z) calcd for C56H68O2NBr: 865.44; Found: 867.6 [M+2H]+. 1

H NMR (CDCl3, 400 MHz): δ 8.21 (d, J = 7.4 Hz, 1H), 8.16 (d, J = 7.2 Hz, 1H), 8.09 (d, J = 8.2

Hz, 1H), 8.07 (d, J = 8.0 Hz, 1H),7.91 (d, J = 8.3 Hz, 1H), 7.86 (d, J = 8.4 Hz, 1H), 7.74 (d, J = 8.2 Hz, 1H), 7.57 (t, J = 8.0 Hz, 1H), 7.34 (t, J = 8.0 Hz ,1H), 7.18 (d, J = 8.1 Hz, 1H), 6.95 (d, J = 9.0 Hz, 4H), 6.77 (d, J = 9.0 Hz, 4H), 3.77 (d, J = 5.6 Hz, 4H), 1.78–1.70 (m, 2H), 1.48–1.28 (m, 32H), 0.91–0.86 (m, J = 6.8 Hz, 12H). 13C NMR (CDCl3, 100 MHz): δ 154.7, 145.1, 142.4, 133.0, 131.7, 131.3, 131.2, 131.1, 130.7, 129.9, 129.6, 127.7, 127.2, 126.8, 126.5, 126.1, 125.0, 123.8, 121.7, 121.2, 121.0, 120.9, 120.0, 115.2, 71.2, 38.0, 31.9, 31.4, 31.1, 29.7, 29.1, 26.9, 23.1, 22.7, 14.1. Compound 3 (1.71 g, 1.97 mmol), copper(I) iodide (0.04 g, 0.20 mmol) and bis(triphenylphosphine)palladium(II) dichloride (0.14 g, 0.20 mmol) were weighted into round bottom flask under nitrogen. A mixture of Et3N (19.8 mL) and THF (30 mL) containing (triisopropylsilyl) acetylene (0.66 mL) were purged with nitrogen for 15 minutes before synringed into the flask. The resulting solution was heated at 110 oC for 5.5 hours. After that,


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volatiles were removed and the resulting residues were purified by column chromatography using silica gel (hexanes/CH2Cl2: 9/1 v/v as eluent) to give red oily product 5 (1.69 g, 88%). M. p.: 112–113 oC; ATR-IR: v 3039, 2968, 2933, 2869, 2140, 1585, 1563, 1509, 1465, 1462, 1379, 1263, 1232, 1055, 1018, 1001, 1006, 883, 843, 812, 771, 766, 694 cm-1; ESI-MS (m/z) calcd for C67H89O2NSi: 967.67; Found: 967.8 [M]+. 1H NMR (CDCl3, 400 MHz): δ 8.25 (d, J = 8.3 Hz, 1H), 8.20 (d, J = 7.6 Hz, 1H), 8.17 (d, J = 7.6 Hz, 1H), 8.11 (d, J = 8.3 Hz, 1H), 8.01 (d, J = 8.0 Hz, 1H), 7.85 (d, J = 8.4 Hz, 1H), 7.68 (d, J = 7.9 Hz, 1H), 7.57 (t, J = 7.9 Hz, 1H), 7.34 (t, J = 8.0 Hz, 1H), 7.19 (d, J = 8.1 Hz, 1H), 6.96 (d, J = 8.9 Hz, 4H), 6.77 (d, J = 9.0 Hz, 4H), 3.77 (d, J = 5.6 Hz, 4H), 1.77 – 1.70 (m, 2H), 1.48 – 1.21 (m, 53H), 0.92 – 0.87 (m, J = 6.8 Hz, 12H). 13C NMR (CDCl3, 100 MHz): δ 154.7, 145.2, 142.4, 136.9, 134.8, 131.8, 131.5, 131.4, 131.3, 130.0, 128.1, 127.4, 127.3, 126.5, 126.1, 126.1, 124.8, 123.8, 121.6, 120.8, 120.5, 119.8, 119.0, 115.1, 105.5, 96.8, 71.11, 38.0, 31.9, 31.4, 31.1, 29.7, 29.1, 26.8, 23.1, 22.7, 18.8, 14.1, 11.5. 4-((10-(bis(4-((2-butyloctyl)oxy)phenyl)amino)perylen-3-yl)ethynyl)benzoic acid (GJ-P). At nitrogen atmosphere a THF solution (80 mL) containing compound 5 (1.69 g, 1.74 mmol) was added 5 equivalent of tetra(n-butyl)ammonium fluoride (1M in THF, 8.7 mL) all at once. The reaction was monitored by TLC until the reaction completed. After that, the mixtures were poured into CH2Cl2 followed by washed with water, dried over anhydrous MgSO4 and evaporated the volatiles under reduced pressure. The resulting red residues were directly used for further reaction. A two-necked round-bottom flask equipped with condenser was charged with the

red

intermediates,

bis(dibenzylideneacetone)palladium(0)

(0.16

g,

0.02

mmol),

triphenylarsine (0.52 g, 0.17 mmol) and 4-iodobenzoic acid (1.27 g, 5.13 mmol) under nitrogen. A mixture of Et3N (60 mL) and THF (130 mL) were purged with nitrogen for 15 minutes before syringed into the flask and the resulting solution was heated at 100 oC for 12 h. After that,


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solvent was removed and the resulting residues were purified by column chromatography using silica gel (CH2Cl2/MeOH: 30/1 v/v as eluent) followed by recrystallization from CH2Cl2/MeOH to gave GJ-P as red powder (1.05 g, yield 65%). M. p.: 186–187 oC; ATR-IR: v 3035, 2950, 2921, 2850, 2185, 1689, 1602, 1585, 1510, 1469, 1458, 1413, 1394, 1315, 1273, 1236, 1174, 1024, 1014, 858, 816, 812, 800, 748, 723, 694 cm-1; ESI-HRMS (m/z) calcd for C65H73O4N: 931.5534; Found: 931.5516 [M]+. 1H NMR (acetone-d6, 400 MHz): δ 8.39 (d, J = 7.6 Hz, 1H), 8.33 (d, J = 8.2 Hz, 2H), 8.29 (d, J = 8.3 Hz, 1H), 8.23 (d, J = 8.0 Hz, 1H), 8.12 (d, J = 8.2 Hz, 2H), 7.87 (d, J = 8.4 Hz, 1H), 7.81 (d, J = 8.2 Hz, 2H), 7.78 (d, J = 7.9 Hz, 1H), 7.66 (t, J = 7.9 Hz, 1H), 7.37 (t, J = 7.9 Hz, 1H), 7.16 (d, J = 8.2 Hz, 1H), 6.92 (d, J = 8.9 Hz, 4H), 6.82 (d, J = 8.9 Hz, 4H), 3.82 (d, J = 5.5 Hz, 4H), 1.77–1.70 (m, 2H), 1.50–1.28 (m, 32H), 0.90–0.85 (m, 12H).

13

C NMR (acetone-d6, 101 MHz): δ 166.87, 155.79, 146.52, 143.17, 132.49, 132.40,

132.25, 131.99, 131.97, 130.58, 128.62, 128.53, 127.40, 126.78, 124.75, 123.09, 122.13, 121.92, 120.30, 119.47, 115.96, 95.29, 91.47, 71.49, 32.47, 31.73, 30.31, 27.42, 23.61, 23.21. The syntheses of compounds GJ-T, GJ-PC, GJ-TC and GJ-BP follow similar route as that of GJ-P. GJ-T: Black powder (Yield 18%). M. p.: 107–108 oC; ATR-IR: v 3033, 2950, 2920, 2850, 2186, 1668, 1583, 1566, 1504, 1464, 1456, 1431, 1394, 1286, 1265, 1240, 1172, 1093, 1022, 810, 808, 762, cm-1; 1H NMR (acetone-d6, 400 MHz): δ 8.45 (d, J = 7.4 Hz, 1H), 8.38 (d, J = 7.2 Hz, 1H), 8.37 (d, J = 8.3 Hz, 1H), 8.30 (d, J = 8.1 Hz, 1H), 8.25 (d, J = 8.3 Hz, 1H), 7.91 (d, J = 8.5 Hz, 1H), 7.82 (d, J = 8.0 Hz, 1H), 7.79 (d, J = 3.9 Hz, 1H), 7.73 – 7.68 (m, 1H), 7.52 (d, J = 3.9 Hz, 1H), 7.42 (d, J = 8.3 Hz, 1H), 7.21 (d, J = 8.2 Hz, 1H), 6.95 (d, J = 9.0 Hz, 4H), 6.86 (d, J = 9.1 Hz, 4H), 3.85 (d, J = 5.6 Hz, 4H), 1.76 (m, 2H), 1.38 (m, 32H), 0.88 (m, J = 7.0 Hz, 12H). 13

C NMR (acetone-d6, 101 MHz): δ 162.29, 155.88, 146.74, 143.23, 134.40, 133.63, 132.50,


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132.03, 128.83, 127.46, 126.82, 126.37, 124.83, 123.29, 122.27, 122.04, 120.35, 118.85, 116.03, 94.82, 88.43, 71.59, 38.77, 32.52, 32.07, 31.78, 27.47, 23.66, 23.26, 14.31. GJ-PC: Black powder (Yield 49%). M. p.: 194–195 oC; ATR-IR: v 3033, 2948, 2918, 2862, 2850, 2198, 2186, 1699, 1695, 1585, 1566, 1541, 1514, 1469, 1462, 1392, 1288, 1259, 1238, 1172, 1091, 1016, 827, 806, 760, 719 cm-1; ESI-HRMS (m/z) calcd for C68H74O4N2: 982.5643; Found: 982.5629 [M]+. 1H NMR (acetone-d6, 400 MHz): δ 8.45 (d, J = 7.6 Hz, 1H), 8.39 – 8.35 (m, 4H), 8.31 (d, J = 8.1 Hz, 1H), 8.20 (d, J = 8.3 Hz, 2H), 7.91 (d, J = 8.4 Hz, 3H), 7.84 (d, J = 7.9 Hz, 1H), 7.71 (t, J = 8.0 Hz, 1H), 7.41 (t, J = 8.0 Hz, 1H), 7.21 (d, J = 8.1 Hz, 1H), 6.95 (d, J = 8.9 Hz, 4H), 6.86 (d, J = 9.0 Hz, 4H), 3.85 (d, J = 5.5 Hz, 4H), 1.79–1.72 (m, 2H), 1.55–1.23 (m, 32H), 0.91–0.86 (m, 12H).

13

C NMR (acetone-d6, 101 MHz): δ 163.33, 155.79, 153.99,

146.60, 143.15, 135.24, 133.37, 132.78, 132.64, 132.41, 131.92, 131.80, 128.69, 127.39, 126.76, 126.53, 124.72, 123.17, 122.17, 121.95, 120.31, 115.96, 95.48, 92.54, 71.48, 38.67, 32.42, 31.97, 31.68, 27.36, 23.55, 23.15, 14.19. GJ-TC: Black powder (Yield 52%). M. p.: 250–251 oC; ATR-IR: v 3037, 2954, 2921, 2850, 2210, 2175, 1695, 1610, 1577, 1585, 1490, 1467, 1460, 1435, 1390, 1363, 1354, 1219, 1043, 1024, 825, 796, 750, 719 cm-1; ESI-MS (m/z) calcd for C63H71O3NS: 921.52; Found: 932.6 [M]+. 1

H NMR (acetone-d6, 400 MHz): δ 8.50 (s, 1H), 8.47 (d, J = 7.4 Hz, 1H), 8.40 (d, J = 8.0, 1H),

8.40 (d, J = 8.0, 1H), 8.33 (d, J = 8.1 Hz, 1H), 8.27 (d, J = 8.5 Hz, 1H), 8.02 (d, J = 4.2 Hz, 1H), 7.92 (d, J = 8.6 Hz, 1H), 7.88 (d, J = 7.9 Hz, 1H), 7.75–7.70 (m, 1H), 7.67 (d, J = 4.0 Hz, 1H), 7.45–7.40 (m, 1H), 7.23 (d, J = 8.2 Hz, 1H), 6.96 (d, J = 9.0 Hz, 4H), 6.87 (d, J = 9.1 Hz, 4H), 3.86 (d, J = 5.6 Hz, 4H), 1.80–1.74 (m, 2H), 1.53–1.29 (m, 32H), 0.91–0.86 (m, 12H). 13C NMR (acetone-d6, 101 MHz): δ 163.62, 155.93, 146.85, 146.66, 143.28, 139.97, 137.92, 135.05, 133.87, 132.85, 132.61, 132.55, 131.96, 130.77, 128.90, 128.79, 127.67, 127.49, 126.77, 126.35,


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125.95, 124.95, 123.46, 122.35, 122.08, 120.37, 118.59, 116.77, 116.08, 100.86, 98.34, 88.77, 71.62, 38.84, 32.60, 32.14, 31.85, 27.55, 23.73, 23.34, 14.39. GJ-BP: Black powder (Yield 65%). M. p.: 284–285 oC; ATR-IR: v 3049, 2956, 2927, 2852, 2189, 1689, 1604, 1575, 1568, 1537, 1502, 1469, 1462, 1419, 1396, 1284, 1248, 1232, 1022, 827, 808, 766, 729, 694 cm-1; ESI-HRMS (m/z) calcd for C71H75O4N3S: 1065.5473; Found: 1065.5470 [M]+. 1H NMR (acetone-d6, 400 MHz): δ 8.70 (d, J = 8.4 Hz, 1H), 8.50 (d, J = 7.8 Hz, 1H), 8.42 (d, J = 8.0 Hz, 2H), 8.36 (d, J = 8.3 Hz, 1H), 8.25 (s, 3H), 8.17 (d, J = 7.5 Hz, 1H), 8.07 (d, J = 7.3 Hz, 1H), 7.92 (d, J = 7.7 Hz, 2H), 7.79 (t, J = 8.0 Hz, 1H), 7.44 (t, J = 8.0 Hz, 1H), 7.24 (d, J = 8.1 Hz, 1H), 6.97 (d, J = 9.0 Hz, 4H), 6.88 (d, J = 9.0 Hz, 4H), 3.87 (d, J = 5.4 Hz, 4H), 1.79- 1.75 (m, 2H), 1.53 – 1.30 (m, 32H), 0.92 – 0.87 (m, 12H). 13C NMR (CDCl3, 151 MHz) δ 156.51, 155.47, 154.81, 152.98, 150.48, 145.61, 142.36, 142.04, 134.87, 132.78, 132.13, 131.73, 131.33, 130.48, 130.08, 129.32, 128.79, 128.37, 128.25, 127.72, 127.27, 126.54, 126.25, 126.01, 125.06, 123.90, 121.97, 121.03, 120.79, 119.12, 118.75, 117.36, 115.18, 96.07, 92.26, 91.40, 71.21, 38.04, 31.85, 31.38, 31.07, 29.69, 29.09, 26.84, 23.06, 22.67, 14.10.

Device fabrication In the DSCs fabrication process, all reagents were purchased in commercially and nearly 99% purified. Also, all fabricating materials and equipment were executed the clean process by supersonication with detergent, DI water, and acetone sequentially. The complete sandwich-typed cell was composed of dye-sensitized photoanode and platinum-deposited counter electrode sealed together by hot melt film (Surlyn, 30 µm) at 120 oC. For each detailed preparation, the photoanode was obtained by using a cleaned fluorine doped tin oxide (FTO) glass (3.1 mm thick, 13 Ω/square, 8% haze) as substrate and then screen-printing the transparent layer with a TiO2


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particle size of 20 nm (Eternal Materials Co., ltd. R.O.C Taiwan) and scattering layer with a TiO2 particle size of 400 nm (CCIC, Japan). The dimension of TiO2 film is 0.4 cm × 0.4 cm (active area of 0.16 cm2). The TiO2 film was subsequently sintered at progressive steps until 500 o

C under the air flow and the thickness of the sintered one was on average of 13 + 3 µm

measured by the portable roughness tester (SURFCOM FLEX, ACCRETECH in Japan). After the thermal post-treatment with 40 mM TiCl4 at 70 °C for 30 minutes and annealing process at 450 °C for 1 hour, the TiO2 electrode were immersed into 0.15 mM perylene dye solution and twofold concentration of chenodeoxycholic acid (CDCA) as additive in equal volumetric ratio of THF and ethanol (v/v, 1:1) for eight-hour dye-loading. For the photocathode, the platinum (Pt) counter electrode was prepared by operating the two-step dip-coating process interpreted that the cleaned FTO glass (2.2 mm thick, 8 Ω/square) immersing into the surfactant agent and poly-Nvinyl-2-pyrrolidone-capped-platinum (PVP-Pt) nano-clustered solution subsequently. After rinsed with deionized water and kept in dry, the PVP-Pt counter was sintered at 325 °C for one hour. The prerequisite work for preparing the PVP-Pt solution was reported in previous study.6970

In succession of the aforementioned the sealing process with two photo-electrode, the device

was then injected with the formulated electrolyte through the hole-drill on the cathode side. Concerning the leakage problem and durability, the viable encapsulation method was implemented by sealing the injection hole with the surlyn sheet and thin cover glass at 120 °C. The shielding mask of 0.36 cm2 was attached on the illuminating side of the device for precisely photovoltaic measurement. The components of electrolyte comprised 0.07 M LiI, 1 M PMII, 0.05 M I2, 0.05 M tBP in acetonitrile/valeronitrile (85:15, v/v).

Characterizations


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Dye loading measurement. The dye loading amount data were determined by executing the desorption process and calculating with the employment of Beer-Lambert Law. The photoanode consisted of transparent TiO2 layer (20 nm) at the average of 12 µm thickness and the active area of 0.16 cm2 (0.4 cm × 0.4 cm in dimension). The dye solution with concentration of 0.15 mM was formulated by dissolving perylenes into THF/EtOH mixture (v/v, 1:1) and the twofold excess of chenodeoxycholic acid (CDCA) as additives. After sensitizing at 25 oC for 14 hrs, the photoanode were rinsed by ethanol and then immersed into 5 mL desorption agent derived from THF and [(n-Bu)4N]OH (0.1 M pre-dissolved in equal volume of H2O and ethanol) at the volumetric ratio of 49:1. Measurement of device performance under artificial sun simulator. In this study, the currentvoltage characteristics at an intensity of 100 mW cm-2 under AM 1.5 G were measured for all perylene-sensitized devices by employing 700W short-arc Xenon lamp equipped in the solar simulator machine (PEC-L15, Peccell Technologies, Inc. Yokohama, Japan) as illuminance source associating with the computer-controlled digital source meter (Keithley 2400C). The light-intensity calibration was executed by using a Si-KG3 filtered solar cell as reference cell. The incident photon-to-current efficiency (IPCE) measurement was performed by using monochromatic light illumination from 150 W Xenon lamp equipped in IPCE machine (PECS20, Peccell Technologies, Inc. Yokohama, Japan). The Si photodiode cell (S1337-1010BQ) was used for spectral calibration reference. Two shading masks with dimensions of 0.38 cm × 0.38 cm (0.14 cm2 area size) and 0.6 cm × 0.6 cm (0.36 cm2 area size) were used in this study. No shaded mask was used for IPCE measurements. The irradiation spot area of IPCE monochromic light source is 0.07 cm2 (0.3 cm in diameter). The "contact irradiation" approach, where the light


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source gently touches the mask-free cell surface, is employed to calculate current density without considering actual cell area (see Supporting Information). EIS Measurement of device performance. The EIS measurements were functioned by using a computer-controlled electrochemical interface workstation (Schlumberger SI-1286) collaborated with a HF frequency response analyzer (Schlumberger SI-1255). The frequency range was from 100 kHz to 0.1 Hz and an AC amplitude was 10 mV. The impedance measurements were carried out under the dark environment and simultaneously the impedance data were recorded as the function of applied DC bias ranged from 0V to xV which is equivalent to the open-circuit voltage of DSCs. The data were then conducted fitting task by Z-View software in employment with a relevant equivalent circuit. Measurement of device performance under dim light. The perylene-based DSCs were operated the J-V characterization under indoor light illumination. The measuring instrument was a mobile cage-lifter wrapped around the black shade curtain. The enclosed facilities equipped inside the lifter are a height-controllable stage where the lightning are loaded and a calibrated spectroradiometer embedded at the bottom platform (ISM-Lux, Isuzu Optics, Japan). The indoor lightning resource are T5 fluorescent lamp (FH14D-EX/T, China Electric Mfg Corporation, Taiwan) and LED-planar (FOP/A/40W/757/U/ 2x2, EVERLIGHT). Prior to the I-V measurement, the calibration process by using the spectroradiometer has already conducted for the precise detection in term of the light intensity. The request for the specific light intensities is achieved by tuning the height of lightning-embedded stage to the moderate position. Subsequently, the DSC sample was put near the calibrated spectroradiometer and then I-V curve was measured by the digital source meter (Keithley 2400C) connected to the program-installed


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PC as function of various indoor-light illumination. The shading mask with dimension of 0.38 cm × 0.38 cm (0.14 cm2 area size) was used for I-V measurement.

ASSOCIATED CONTENT Supporting Information The Supporting Information is available free of charge on the ACS Publications website. Experimental details; electrochemical measurements; device measurement data; IR and 1

H and 13C NMR spectra (PDF)

AUTHOR INFORMATION Corresponding Author *C.-Y.Y.: [email protected] *T.-C.W.: [email protected] Author Contributions §

H.-H.C. and Y.-C.L. contributed equally to this work.

ACKNOWLEDGMENT


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The authors acknowledge the financial support for this work from the Ministry of Science and Technology (MOST) in Taiwan with Grants MOST 104-2119-M-005-005-MY3 and MOST 1052628-E-007-012-MY3.

REFERENCES (1) Hagfeldt, A.; Boschloo, G.; Sun, L.; Kloo, L.; Pettersson, H. Dye-Sensitized Solar Cells. Chem. Rev. 2010, 110, 6595-6663. (2) Hagfeldt, A.; Grätzel, M. Molecular Photovoltaics. Acc. Chem. Res. 2000, 33, 269277. (3) Fakharuddin, A.; Jose, R.; Brown, T. M.; Fabregat-Santiago, F.; Bisquert, J. A Perspective on the Production of Dye-sensitized Solar Modules. Energy Environ. Sci. 2014, 7, 3952-3981. (4) Tingare, Y. S.; Vinh, N. S. n.; Chou, H.-H.; Liu, Y.-C.; Long, Y.-S.; Wu, T.-C.; Wei, T.C.; Yeh, C.-Y. New Acetylene-Bridged 9,10-Conjugated Anthracene Sensitizers: Application in Outdoor and Indoor Dye-Sensitized Solar Cells. Adv. Energy Mater. 2017, 7 (18), 1700032. (5) Liu, Y.-C.; Chou, H.-H.; Ho, F.-Y.; Wei, H.-J.; Wei, T.-C.; Yeh, C.-Y. A Feasible Scalable Porphyrin Dye for Dye-Sensitized Solar Cells under One Sun and Dim Light Environments. J. Mater. Chem. A 2016, 4 (30), 11878-11887. (6) Wang, C.-L.; Lin, P.-T.; Wang, Y.-F.; Chang, C.-W.; Lin, B.-Z.; Kuo, H.-H.; Hsu, C.W.; Tu, S.-H.; Lin, C.-Y. Cost-Effective Anthryl Dyes for Dye-Sensitized Cells under One Sun and Dim Light. J. Phys. Chem. C 2015, 119 (43), 24282-24289. (7) Chen, C.-Y.; Chang, J.-H.; Chiang, K.-M.; Lin, H.-L.; Hsiao, S.-Y.; Lin, H.-W.


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Chart 1. Molecular structures of perylene derivatives

Ar

N Ar

= phenyl, thienyl

N Ar

perylene (P)

N-fused perylene (NP)

polycyclic aromatic hydrocarbons (PAH)

Scheme 1. Synthesis of compound 5 RO Br

OR

RO

OR

N H cat. Pd2(dba)3, P(t-Bu)3 NaO(t-Bu)

N

toluene (58%) 1

2 NBS CH2Cl2 (86%)

RO

OR

X

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


RO

OR

N

N 3

3

10

9

Br

Br 4

3 TIPSA cat. Pd(PPh3)2Cl2, CuI Et3N, THF (88%) RO

OR N C4H9 R=

C6H13

Si

5


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Page 36 of 43

Scheme 2. Synthetic protocol of perylene dyes RO

RO

OR

OR N

N 1) (n-Bu)4NF, THF 2)

Ac

I ,

cat. Pd2(dba)3, AsPh3 Et3N, THF Si Ac

5

CO2H Ac

=

S

GJ-P (65%)

CO2H GJ-T (18%)

N

S

N CO2H

NC

NC CO2H GJ-PC (49%)

S

CO2H

GJ-BP (65%)

GJ-TC (52%)

Figure 1. (a) 2D NMR COSY and (b) 1D NMR 1H and ROESY spectra of compound 5.


36

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4 2

5 GJ-P GJ-T GJ-PC GJ-TC GJ-BP

1.0 0.5

4

0.0

3x10

(c) 4

2x10

4

1x10

Photon Flux -1 (µW cm )

(b)

6

Absorption Intensity (a.u.)

(a)

0 400

500

600

700

Wavelength (nm)

Figure 2. UV-vis absorption spectra of perylenes (a) in THF and (b) as thin films absorbed on TiO2; (c) the emitting profiles of T5 and LED lights.

(a)

(b) 80

12 -2

Current Density (mA cm )

60

8

GJ-P GJ-T GJ-PC GJ-TC GJ-BP

4

0 0.0

IPCE (%)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


40 GJ-P GJ-T GJ-PC GJ-TC GJ-BP

20

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

400

Voltage (V)

500

600

700

800

Wavelength (nm)

Figure 3. (a) J-V plots and (b) IPCE spectra of devices fabricated with GJ-series dyes.


37

10

3

10

2

10

1

(b)

GJ-P GJ-T GJ-PC GJ-TC GJ-BP

3

10

2

10

(c) 10

-2

2

Rct (Ω cm )

(a)

τe (sec)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 38 of 43

Cµ (µF cm )


-1

0.46

0.48

0.50

0.52

0.54

0.56

0.58

Voltage (V)

Figure 4. Plots of (a) recombination resistances (Rrec), (b) chemical capacitances (Cµ), and (c) electron lifetimes (τe) for perylene dye devices versus applied bias voltage ranging between 0.475 and 0.575 V in the dark.

= surface dipole N S N

Ar NC

O

O

O O

NC

Ar

O O

S O O

TiO2 surface

= electrolytes

TiO2 surface

Figure 5. Schematic representation of dye molecular arrangements and electrolyte penetration behavior on TiO2 surface.


38

0.8 -2

30 25

Sun T5 LED

20

0.6

GJ-P GJ-BP

0.4 0.2 0.0

0.8

15 0.6

10

0.4

1

10

100

Pmax (mW)

0.06

5

VOC (V)

(b)

(a)

PCE (%)

0.03

0.00 0

-2

2,000

Input Power (mW cm )

4,000

6,000

Illuminance (lux)

Figure 6. (a) PCE of GJ-BP cell as the function of light intensities under sun, T5 and LED. (b) Short-circuit current, open-circuit voltage and power output for GJ-BP and GJ-P cells as a function of T5 dim light illuminance.

o

o

o

30 C

~ 25 C

40 C

6

PCE (%)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


JSC (mA cm )

Page 39 of 43

4 GJ-P GJ-T GJ-PC GJ-TC GJ-BP GJ-BP (MPN-based electrolyte)

2

0 0

500

1000

1500

2000

2500

3000

3500

Time (hr)

Figure 7. Stability test of perylene DSCs with liquid (for all dyes) or ionic liquid electrolyte (for GJ-BP). The programmed temperature is given as following: 25 oC for 1877 hr, 30 oC for 800 hr and 40 oC for 800 hr.


39


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Table 1. Photophysical and electrochemical data for perylene dyes λabs (ε),a

E0-0,b

E1/2ox/E1/2red,c

HOMO,d

E0-0*,e

nm (104 M-1 cm-1)

V

V vs Fc/Fc+

V vs NHE

V vs NHE

GJ-P

427sh (1.72), 520 (4.04)

2.14

+0.17 / NA

0.80

-1.34

GJ-T

434sh (1.75), 525 (3.69)

2.13

+0.17, +0.61 / -1.89

0.80

-1.33

GJ-PC

428sh (1.55), 528 (3.84)

2.11

+0.18, +0.59 / -1.97

0.81

-1.31

2.05

+0.17, +0.60 / -1.78

0.80

-1.25

2.03

+0.15, +0.59 / -1.77

0.78

-1.25

GJ-TC GJ-BP

375 (2.05), 448sh (2.25), 545 (4.75) 449sh (1.63), 541 (3.54)

a

Absorption is measured in THF at 25 oC. bOptical bandgap. cRedox potentials are measured in CH2Cl2 containing 0.1 M [(n-Bu)4N]PF6 as supporting electrolyte. Potentials are reported vs ferrocene/ferrocenium (Fc/Fc+). dHighest-occupied molecular orbitals (HOMO) are calculated from E1/2ox converted to that vs normal hydrogen electrode (NHE) by addition of +0.63 V. e Excitated state energy (E0-0*) is obtained from HOMO and optical bandgap (E0-0) using the formula: E0-0* = HOMO – E0-0.


40

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Table 2. Averaged photovoltaic performance of DSCs sensitized with perylene dyes under AM1.5G conditiona JSC, mA cm

VOC, -2

FF

V

η,

Dye Loading,

%

10-7 mol cm-2

GJ-P

10.554 ± 0.465

0.681 ± 0.003

0.724 ± 0.030

5.194 ± 0.063

1.036

GJ-T

10.080 ± 0.385

0.654 ± 0.006

0.724 ± 0.020

4.763 ± 0.123

1.124

GJ-PC

9.960 ± 0.343

0.633 ± 0.008

0.711 ± 0.017

4.483 ± 0.119

1.144

GJ-TC

11.199 ± 0.129

0.637 ± 0.016

0.730 ± 0.009

5.209 ± 0.230

1.134

GJ-BP

12.460 ± 0.547

0.657 ± 0.029

0.734 ± 0.007

6.000 ± 0.095

1.556

a

2

The active area of TiO2 film is 0.16 cm (0.4 cm × 0.4 cm in dimension); The area of shading mask used is 0.14 cm2 (0.38 cm × 0.38 cm in dimension); Data are represented as averaged values with s.d. each calculated from four devices.


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SYNOPSIS


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Structurally Simple and Easily Accessible Perylenes for Dye

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