Abstract
Two soluble acceptor–donor–acceptor (A–D–A) type organic small molecules, 2,2′-(5,5′-(1E,1′E)-2,2′-(benzo[c][1,2,5]thiadiazole-4,7-diyl)bis(ethene-2,1-diyl)bis(3,4-dihexylthiophene-5,2-diyl))bis(methan-1-yl-1-ylidene)dimalononitrile (BvT-DCN) and 2,2′-(3,3′-(1E,1′E)-2,2′-(5,5′-(1E,1′E)-2,2′-(benzo[c][1,2,5]thiadiazole-4,7-diyl)bis(ethene-2,1-diyl)bis(3,4-dihexylthiophene-5,2-diyl))bis(ethene-2,1-diyl)bis(5,5-dimethylcyclohex-2-ene-3-yl-1-ylidene))dimalononitrile (BT-C6), were synthesized by Knoevenagel condensation reaction based on benzothiadiazole, thiophene, and different terminal electron-withdrawing groups. The acceptor group benzothiadiazole and donor group thiophene inside the molecules are connected by all-trans double bonds, which ensures the benzothiadiazole and thiopene groups are in the same plane and makes the molecules have a relative narrow band gap and absorb sunlight in the long wavelength. The terminal electron-withdrawing groups, malononitrile and 2-(5,5-dimethylcyclohex-2-en-1-ylidene)malononitrile (DCM), are symmetrically introduced into the molecules, respectively, to tune the energy level and extend the absorption of the molecules. The UV–Vis absorption spectrum and cyclic voltammetry measurements indicated that BT-C6 has a lower energy band gap (1.60 eV) than BvT-DCN (1.71 eV), which arises from the stronger electron-withdrawing ability of DCM group in BT-C6 than that of malononitrile group in BvT-DCN. And BvT-DCN and BT-C6 have nearly the same highest occupied molecular orbital energy level, −5.74 eV for BvT-DCN and −5.72 eV for BT-C6 due to the same electron–donor group of the two compounds. Bulk heterojunction photovoltaic devices were fabricated using BvT-DCN or BT-C6 as donor and (6,6)-phenyl C61-butyric acid methyl ester as acceptor. The device based on BT-C6 has a higher (~8 times) short circuit current and power conversion efficiency than the device based on BvT-DCN, resulting from the wider solar light absorption of BT-C6 and smaller phase separation dimension of the active layer based on BT-C6.
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References
Gunes S, Neugebauer H, Sariciftci NS (2007) Conjugated polymer-based organic solar cells. Chem Rev 107:1324–1338
Brabec CJ (2004) Organic photovoltaics: technology and market. Sol Energy Mater Sol Cells 83:273–292
Scharber MC, Wuhlbacher D, Koppe M et al (2006) Design rules for donors in bulk-heterojunction solar cells-towards 10 % energy-conversion efficiency. Adv Mater 18:789–794
Zhou JY, Wan XJ, Liu YS et al (2012) Small molecules based on benzo[1,2-b:4,5-b′]dithiophene unit for high-performance solution-processed organic solar cells. J Am Chem Soc 134:16345–16351
Sun YM, Welch GC, Leong WL, Takacs CJ, Bazan GC, Heeger AJ (2012) Solution-processed small-molecule solar cells with 6.7 % efficiency. Nat Mater 11:44–48
Van der Poll TS, Love JA, Nguyen TQ, Bazan GC (2012) Non-basic high-performance molecules for solution-processed organic solar cells. Adv Mater 24:3646–3649
Kroon R, Lenes M, Hummelen JC, Blom PWM, De Boer B (2008) Small bandgap polymers for organic solar cells (polymer material development in the last 5 years). Polym Rev 48:531–582
Wu PT, Kim FS, Champion RD, Jenekhe SA (2008) Conjugated donor-acceptor copolymer semiconductors: synthesis, optical properties, electrochemistry, and field-effect carrier mobility of pyridopyrazine-based copolymers. Macromolecules 41:7021–7028
Thompson BC, Kim YG, McCarley TD, Reynolds JR (2006) Soluble narrow band gap and blue propylenedioxythiophene–cyanovinylene polymers as multifunctional materials for photovoltaic and electrochromic applications. J Am Chem Soc 128:12714–12725
Rousseau T, Cravino A, Bura T, Ulrich G, Ziessel R, Roncali J (2009) BODIPY derivatives as donor materials for bulk heterojunction solar cells. Chem Commun 13:1673–1675
Zhang J, Yang Y, He C, He YJ, Zhao GJ, Li YF (2009) Solution-processable star-shaped photovoltaic organic molecule with triphenylamine core and benzothiadiazole-thiophene arms. Macromolecules 42:7619–7622
Li ZF, Dong QF, Li YW et al (2011) Design and synthesis of solution processable small molecules towards high photovoltaic performance. J Mater Chem 21:2159–2168
Li ZF, Dong QF, Xu B et al (2011) New amorphous small molecules-synthesis, characterization and their application in bulk heterojunction solar cells. Sol Energy Mater Sol Cells 95:2272–2280
Li ZF, Dong QF, Xu B et al (2012) Novel solution processable small molecule containing new electron-withdrawing group and oligothiophene for photovoltaic applications. Sol Energy Mater Sol Cell 98:343
Li Q, Liu ZY, Liu LJ et al (2012) Alkyl chain effect and photoelectric properties of d–a–d structural solution processable organic small molecules. Chem J Chin Univ 33:182–187
Li ZF, Peng Q, He P et al (2012) Progress of solution processable donor–acceptor organic small molecular solar cell materials. Chin J Org Chem 32:834–851
Li C, Chen YJ, Zhao Y et al (2013) Acceptor–donor–acceptor-based small molecules with varied crystallinity: processing additive-induced nanofibril in blend film for photovoltaic applications. Nanoscale 5:9536–9540
Lai YY, Yeh JM, Tsai CE, Cheng YJ (2013) Synthesis, molecular and photovoltaic properties of an indolo[3,2-b]indole-based acceptor–donor–acceptor small molecule. Eur J Org Chem 2013:5076–5084
Hirade M, Yasuda T, Adachi C (2013) Effects of intramolecular donor–acceptor interactions on bimolecular recombination in small-molecule organic photovoltaic cells. J Phys Chem C 117:4986–4991
Ye DD, Li XD, Yan L, Zhang WJ, Hu Z, Liang Y, Fang JF, Wong WY, Wang XZ (2013) Dithienosilole-bridged small molecules with different alkyl group substituents for organic solar cells exhibiting high open-circuit voltage. J Mater Chem A 1:7622–7629
Hu Z, Li XD, Zhang WJ, Liang AH, Ye DD, Liu ZT, Liu J, Liu YJ, Fang JF (2014) Synthesis and photovoltaic properties of solution processable star-shaped small molecules with triphenylamine as the core and alkyl cyanoacetate or 3-ethylrhodanine as the end-group. RSC Adv 4:5591–5597
Li ZF, Pei JN, Li YW et al (2010) Synthesis and photovoltaic properties of solution processable small molecules containing 2-pyran-4-ylidenemalononitrile and oligothiophene moieties. J Phys Chem C 114:18270–18278
Massin J, Dayoub W, Mulatier JC, Aronica C, Bretonniere Y, Andraud C (2011) Near-infrared solid-state emitters based on isophorone: synthesis, crystal structure and spectroscopic properties. Chem Mater 23:862–873
Ozyurt F, Gunbas EG, Durmus A, Toppare L (2008) Processable and multichromic polymer of bis-3-hexylthiophene substituted 4-tert-butylphenyl quinoxaline. Org Electron 9:296–302
Kawahara N, Tomita E, Ohtsuki A, Aoyagi Y (2011) Cycle-resolved residual gas concentration measurement inside a heavy-duty diesel engine using infrared laser absorption. Proc Combust Inst 33:2903–2910
Li Z, Ding JF, Song NH, Lu JP, Tao Y (2010) Development of a new s-tetrazine-based copolymer for efficient solar cells. J Am Chem Soc 132:13160–13161
Cervima R, Lz X-C, Spencer GWC, Holmes AB, Moratti SC, Friend RH (1997) Electrochemical and optical studies of PPV derivatives and poly(aromatic oxadiazoles). Synth Met 84:359–360
Blouin N, Michaud A, Leclerc M (2007) A low-bandgap poly(2,7-carbazole) derivative for use in high-performance solar cells. Adv Mater 19:2295–2300
Brabec CJ, Cravino A, Meissner D et al (2001) Origin of the open circuit voltage of plastic solar cells. Adv Funct Mater 11:374–380
Halls JJM, Pichler K, Friend RH, Moratti SC, Holmes AB (1996) Exciton diffusion and dissociation in a poly(p-phenylenevinylene)/C60 heterojunction photovoltaic cell. Appl Phys Lett 68:3120–3122
Lunt RR, Giebink NC, Belak AA, Benziger JB, Forrest SR (2009) Exciton diffusion lengths of organic semiconductor thin films measured by spectrally resolved photoluminescence quenching. J Appl Phys 105:053711
Li G, Shrotriya V, Yao Y, Yang Y (2005) Investigation of annealing effects and film thickness dependence of polymer solar cells based on poly(3-hexylthiophene). J Appl Phys 98:043704–043705
Tore N, Parlak EA, Usluer O, Egbe DAM, San SE, Aydogan P (2012) Effect of blend ratio on poly(p-phenylene-ethynylene)-alt-poly (p-phenylene-vinylene) polymer solar cell. Sol Energy Mater Sol Cells 104:39–44
Acknowledgements
This work was supported by 973 program (2014CB643506), the Project Sponsored by the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry, the Research Fund of Key Laboratory of Physics and Technology for Advanced Batteries, Ministry of Education (Grant no. 201206), and the Research Fund of State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, Jilin University (Grant no. 2011-25).
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Liu, L., Li, H., Zhang, X. et al. Synthesis, characterization, and photovoltaic properties of acceptor–donor–acceptor organic small molecules with different terminal electron-withdrawing groups. J Mater Sci 49, 5279–5288 (2014). https://doi.org/10.1007/s10853-014-8228-x
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DOI: https://doi.org/10.1007/s10853-014-8228-x