Effects of end-capped acceptors subject to subtle structural changes on solution-processable small molecules for organic solar cells. Issue 14 (6th March 2015)

• Record Type: Journal Article
• Authors: Deng, Dan; Zhang, Yajie; Zhu, Lingyun; Zhang, Jianqi; Lu, Kun; Wei, Zhixiang
• Is Part Of: Physical chemistry chemical physics. Volume 17:Issue 14(2015)
• Page Start: 8894
• Page End: 8900
• Publication Date: 2015-03-06
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.3
• DOI: 10.1039/c5cp00042d
• Languages: English
• ISSNs: 1463-9076

Abstract

Abstract : Three subtle structural changed end-capped acceptors with increased electron withdrawing ability were synthesized and introduced into a planar conjugated backbone. The relationship between molecules bearing the three end-capped acceptors and their photovoltaic properties was studied. Abstract : Self-assembly is crucial for small molecular organic solar cells, which are extremely sensitive to the molecular structure. In this work, three subtle structural changed end-capped acceptors with increased electron withdrawing ability, named octyl 2-cyanoacetate (CNCOOC8 H17 ), 3-oxoundecanenitrile (CNCOC8 H17 ), and 2-(octylsulfonyl) acetonitrile (CNSOOC8 H17 ), were synthesized and introduced into a planar conjugated backbone using ethylhexyl-thiophene substituted benzodithiophene (TBDT) as a core and trithiophene as a π-bridge (labelledM1, M2 andM3, respectively). Their effects on absorption, thermal properties, and morphologies were studied and compared. In particular, the molecular packing of the three materials varied significantly, and the hole mobilities differed by orders of magnitude. As a result, the fill factors of devices varied from 52% to 72%. Combining the effects of electron-withdrawing capability and molecular packing, the power conversion efficiencies of the optimized devices increased from 3.0% forM3 to 6.4% forM1 andM2 . The relationship between end-capped acceptors and photovoltaic properties would generate valuable insights into further producing more efficient solution-processable organic solar cells.