title: A Bromo-Functionalized Conjugated Polymer as a Cross-Linkable Anode Interlayer of Polymer Solar Cells.
abstract: A cross-linkable conjugated polymer with bromo groups on the side chain has been developed and used as an anode interlayer to improve the active layer morphology and consequently enhance the device performance of polymer solar cells (PSCs). The polymer, PCDTBT-Br, has cross-linkable bromo groups attached to the side chain of a widely-used donor polymer, poly[N-9-heptadecanyl-2,7-carbazole-alt-5,5-(4,7-di-2-thienyl-2,1,3-benzothiadiazole)] (PCDTBT). The pendant bromo groups do not significantly change the LUMO/HOMO energy levels and absorption spectrum of the PCDTBT polymer backbone. PDCTBT-Br can crosslink under UV irradiation to give a robust film, which enables multilayer PSC device fabrication. Moreover, the much lower surface energy of PCDTBT-Br (20.4 mJ m(-2) ) compared to
  
  
  
  PSS (91.6 mJ m(-2) ) is beneficial for achieving optimal active layer morphology. As a result, with PCDTBT:[6,6]-phenyl-C71 butyric acid methyl ester (PC71 BM) as the active layer, the PSC device with PCDTBT-Br as the underlying layer shows a power conversion efficiency (PCE) of 6.59 %, in comparison to a PCE of 5.86 % of the control device. The device performance enhancement is ascribed to the much improved phase separation with a fibrillar nanostructure in the active layer.
authors.affiliation: State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, P. R. China.
authors.forename: Bin
authors.initials: B
authors.lastname: Meng
authors.affiliation: State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, P. R. China.
authors.forename: Zhiyuan
authors.initials: Z
authors.lastname: Xie
authors.affiliation: State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, P. R. China. liujun@ciac.ac.cn.
authors.forename: Jun
authors.initials: J
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, P. R. China. lixiang@ciac.ac.cn.
authors.forename: Lixiang
authors.initials: L
authors.lastname: Wang
keywords: active layer morphology; anode interlayer; cross link; polymer solar cells