title: Electrolytes as Cathode Interlayers in Inverted Organic Solar Cells: Influence of the Cations on Bias-Dependent Performance.
abstract: The performance of organic solar cells (OSCs) with edetate electrolytes depends on external bias, and ions are speculated to be responsible for this phenomenon. To clarify the detailed relationship between the ions of electrolytes and the bias-dependent behaviors of devices, this work introduces four edetate cathode interlayers (EDTA-X, X = nH(4-n)Na, n = 0, 1, 2, and 4) containing different kinds and number of cations into inverted OSCs. The results show that the devices initial and saturated (after external bias treatment) power conversion efficiencies (PCEs) both decrease with the increase in the number of H+. Moreover, the bias-dependent degrees increase with the increase in H+number; with that, the PCE increment of EDTA-4H device is 53.4%, while that of the EDTA-4Na device is almost unchanged. The electrical impedance spectroscopy and capacitance-voltage tests reveal that the interfacial recombination is greatly suppressed by external bias treatment, which is not a result of the decreased density of defect states. The results indicate that the ion's motion, specifically the H+motion, under external electrical field is responsible for the bias-dependent behavior, which is conducive to the design of new efficient electrolytic interlayers without bias-dependent performance.
authors.affiliation: Department of Chemistry, College of Sciences, Shanghai University , Shanghai 200444, China.|Key Laboratory of Graphene Technologies and Applications of Zhejiang Province, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences , Ningbo 315201, China.
authors.forename: Yaru
authors.initials: Y
authors.lastname: Li
authors.affiliation: Key Laboratory of Graphene Technologies and Applications of Zhejiang Province, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences , Ningbo 315201, China.
authors.forename: Xiaohui
authors.initials: X
authors.lastname: Liu
authors.affiliation: Key Laboratory of Graphene Technologies and Applications of Zhejiang Province, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences , Ningbo 315201, China.
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Li
authors.affiliation: Key Laboratory of Graphene Technologies and Applications of Zhejiang Province, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences , Ningbo 315201, China.
authors.forename: Wenjun
authors.initials: W
authors.lastname: Zhang
authors.affiliation: Department of Chemistry, College of Sciences, Shanghai University , Shanghai 200444, China.
authors.forename: Feifei
authors.initials: F
authors.lastname: Xing
authors.affiliation: Key Laboratory of Graphene Technologies and Applications of Zhejiang Province, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences , Ningbo 315201, China.
authors.forename: Junfeng
authors.identifier: http://orcid.org/0000-0003-2094-8678
authors.initials: J
authors.lastname: Fang
keywords: cathode interlayer; edetate electrolytes; external bias; ion motion; organic solar cells