title: Evolved phase separation toward balanced charge transport and high efficiency in polymer solar cells.
abstract: Understanding effect of morphology on charge carrier transport within polymer/fullerene bulk heterojunction is necessary to develop high-performance polymer solar cells. In this work, we synthesized a new benzodithiophene-based polymer with good self-organization behavior as well as favorable morphology evolution of its blend films with PC(71)BM under improved processing conditions. Charge carrier transport behavior of blend films was characterized by space charge limited current method. Evolved blend film morphology by controlling blend composition and additive content gradually reaches an optimized state, featured with nanoscale fibrilla polymer phase in moderate size and balanced mobility ratio close to 1:1 for hole and electron. This optimized morphology toward more balanced charge carrier transport accounts for the best power conversion efficiency of 3.2%, measured under simulated AM 1.5 solar irradiation 100 mW/cm(2), through enhancing short circuit current and reducing geminate recombination loss.
authors.affiliation: Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: Haijun
authors.initials: H
authors.lastname: Fan
authors.forename: Maojie
authors.initials: M
authors.lastname: Zhang
authors.forename: Xia
authors.initials: X
authors.lastname: Guo
authors.forename: Yongfang
authors.initials: Y
authors.lastname: Li
authors.forename: Xiaowei
authors.initials: X
authors.lastname: Zhan
mesh_terms: D037741:Fullerenes / Q000737:chemistry; D018625:Microscopy, Atomic Force; D011108:Polymers / Q000737:chemistry*; D012993:Solar Energy; D013876:Thiophenes / Q000737:chemistry
chemical_list: D037741:Fullerenes; D011108:Polymers; D013876:Thiophenes