Terminal moiety-driven electrical performance of asymmetric small-molecule-based organic solar cells. Issue 40 (26th September 2016)

• Record Type: Journal Article
• Authors: Huang, Jianhua; Zhang, Shanlin; Jiang, Bo; Chen, Yuxia; Zhang, Xinliang; Fan, Zhuxin; Yu, Donghong; Lin, Zhiyong; Yao, Jiannian; Zhan, Chuanlang
• Is Part Of: Journal of materials chemistry. Volume 4:Issue 40(2016)
• Page Start: 15688
• Page End: 15697
• Publication Date: 2016-09-26
• Subjects: Materials -- Research -- Periodicals; Chemistry, Analytic -- Periodicals; Environmental sciences -- Research -- Periodicals; 543.0284
• DOI: 10.1039/c6ta07450b
• Languages: English
• ISSNs: 2050-7488

Abstract

Abstract : With respect to the successes from symmetric small molecules, asymmetric ones have recently emerged as an alternative choice. Abstract : With respect to the successes from symmetric small molecules, asymmetric ones have recently emerged as an alternative choice. In this paper, we present the synthesis and photovoltaic properties of four asymmetric small molecule donors. The benzo[1, 2- b :4, 5- b ′]dithiophene (BDT) end in the asymmetric push–pull CNR–DPP–BDT (CNR = octyl-2-cyano-3-(thiophen-2-yl)acrylate, DPP = diketopyrrolopyrrole) was tailored from hydrogen (H) to thiophene (T), 2-hexylbithiophene (HTT), and CNR, respectively, obtainingM1, M2, M3, andM4 . In this order, the donor–donor interactions are enhanced with an increase of intermolecular forces, such as π–π-stacking and van de Waals forces, which enhances aggregation of the donor molecules. In parallel, the molecular dipolarity (| μ |) increases in this order from 5.39 D to 6.26 D, 6.34 D, and 6.92 D, respectively, gradually deviating from the value of PC71 BM (5.01 D). The increase in the donor-to-PC71 BM doplarity difference acts as another factor for enhancing the donor-to-PC71 BM phase-separation. The donor/acceptor domain sizes increase fromM1 (10 nm) toM2 (20 nm) andM3 (50 nm), and even formation of island-like mesostructured PC71 BM aggregates (200 nm) forM4, corresponding to declined short-circuit current density ( J sc ) and fill factor (FF) as well as hole mobility ( μ h ) fromM1 toM4 . This work reveals that control over the terminal moieties of asymmetric small molecules can be an important factor in tailoring photovoltaic performance.