Regulating Bulk‐Heterojunction Molecular Orientations through Surface Free Energy Control of Hole‐Transporting Layers for High‐Performance Organic Solar Cells

• DOI: 10.1002/adma.201806921
• Publication Date: 2019-03-11T18:38:14Z
• Authors: Jianqiu Wang; Zhong Zheng; Dongyang Zhang; Jianqi Zhang; Jiyu Zhou; Jingchong Liu; Shenkun Xie; Yong Zhao; Yuan Zhang; Zhixiang Wei; Jianhui Hou; Zhiyong Tang; Huiqiong Zhou
• Keywords: Sulfonic acid

Abstract Interface properties are of critical importance for high‐performance bulk‐heterojunction (BHJ) organic solar cells (OSCs). Here, a universal interface approach to tune the surface free energy (γ S ) hole‐transporting layers (HTLs) in wide range through introducing poly(styrene sulfonic acid) sodium salts or nickel formate dihydrate into poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is reported. Based on optimal γ HTLs and thus improved face‐on molecular ordering BHJs, enhanced fill factor power conversion efficiencies both fullerene nonfullerene OSCs achieved, which attributed increased charge carrier mobility sweepout with reduced recombination. It found that orientation‐preferred BHJs (PBDB‐TF:PC 71 BM, PBDB‐T:PC PBDB‐TF:IT‐4F) favor higher while edge‐on (PDCDT:PC P3HT:PC BM PDCBT:ITIC) partial lower . property–morphology–device performance correlations, suggestion select suitable HTL terms specific BHJ favored arrangement provided. This work enriches fundamental understandings characteristics morphological control toward high‐efficiency based materials.