title: Solution-Processed 8-Hydroquinolatolithium as Effective Cathode Interlayer for High-Performance Polymer Solar Cells.
abstract: Solution-processed 8-hydroxyquinolinatolithium (s-Liq) was successfully applied as an efficient cathode interlayer in bulk heterojunction polymer solar cells (PSCs), giving rise to enhancement in device performance. The ultraviolet photoelectron spectra results revealed that the presence of s-Liq could lower work function of Al cathode, allowing for the ohmic contacts with the fullerene acceptor for better electron extraction and also a larger work function difference between the two electrodes, which leads to an increase in open-circuit voltage (V(oc)). Scanning Kelvin probe microscopy study on the surface potential of active layers suggested that an interfacial dipole was formed in the s-Liq interlayer between the active layer and the Al cathode, which enhanced the intrinsic built-in potential in the device for better charge transportation and extraction. Consequently, the V(oc), fill factor, and current density of the device can be improved by the introduction of s-Liq interlayer, leading to a power conversion efficiency (PCE) improvement. With PTB7 (or PTB7-Th) as the donor and PC71BM as the acceptor, the s-Liq-based PSC devices exhibited a PCE of 8.37% (or 9.04%), much higher than those of devices with the evaporated Liq (7.62%) or commonly used PFN (8.14%) as the cathode interlayer. Moreover, the s-Liq-based devices showed good stability, maintaining 75% (in N2) and 45% (in air) of the initial PCE after 7 days, respectively. These results suggest the great potential of s-Liq as cathode interlayer material for high-performance solar cells application.
authors.affiliation: MOE Key Laboratory of Macromolecular Synthesis and Functionalization, State Key Laboratory of Silicon Materials, Department of Polymer Science and Engineering, Zhejiang University , Hangzhou 310027, P. R. China.
authors.forename: Wenqing
authors.initials: W
authors.lastname: Liu
authors.affiliation: MOE Key Laboratory of Macromolecular Synthesis and Functionalization, State Key Laboratory of Silicon Materials, Department of Polymer Science and Engineering, Zhejiang University , Hangzhou 310027, P. R. China.
authors.forename: Tao
authors.initials: T
authors.lastname: Liang
authors.affiliation: i-Lab, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Science , Suzhou, Jiangsu 215123, P. R. China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Chen
authors.affiliation: MOE Key Laboratory of Macromolecular Synthesis and Functionalization, State Key Laboratory of Silicon Materials, Department of Polymer Science and Engineering, Zhejiang University , Hangzhou 310027, P. R. China.
authors.forename: Zhikai
authors.initials: Z
authors.lastname: Yu
authors.affiliation: MOE Key Laboratory of Macromolecular Synthesis and Functionalization, State Key Laboratory of Silicon Materials, Department of Polymer Science and Engineering, Zhejiang University , Hangzhou 310027, P. R. China.
authors.forename: Yingying
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: MOE Key Laboratory of Macromolecular Synthesis and Functionalization, State Key Laboratory of Silicon Materials, Department of Polymer Science and Engineering, Zhejiang University , Hangzhou 310027, P. R. China.
authors.forename: Yujing
authors.initials: Y
authors.lastname: Liu
authors.affiliation: MOE Key Laboratory of Macromolecular Synthesis and Functionalization, State Key Laboratory of Silicon Materials, Department of Polymer Science and Engineering, Zhejiang University , Hangzhou 310027, P. R. China.
authors.forename: Weifei
authors.initials: W
authors.lastname: Fu
authors.affiliation: i-Lab, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Science , Suzhou, Jiangsu 215123, P. R. China.
authors.forename: Feng
authors.initials: F
authors.lastname: Tang
authors.affiliation: i-Lab, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Science , Suzhou, Jiangsu 215123, P. R. China.
authors.forename: Liwei
authors.initials: L
authors.lastname: Chen
authors.affiliation: MOE Key Laboratory of Macromolecular Synthesis and Functionalization, State Key Laboratory of Silicon Materials, Department of Polymer Science and Engineering, Zhejiang University , Hangzhou 310027, P. R. China.
authors.forename: Hongzheng
authors.initials: H
authors.lastname: Chen
keywords: Liq; PCE; PSC; cathode interlayer; stability; work function