Counterion induced facile self-doping and tunable interfacial dipoles of small molecular electrolytes for efficient polymer solar cells. (September 2016)

• Record Type: Journal Article
• Authors: Chen, Lie; Tan, Yun; Liu, Xiangfu; Chen, Yiwang
• Is Part Of: Nano energy. Volume 27(2016:Sep.)
• Page Start: 492
• Page End: 498
• Publication Date: 2016-09
• Subjects: Polymer solar cells -- Polyelectrolytes -- Counterions -- Self-doping -- Interfacial engineering; Nanoscience -- Periodicals; Nanotechnology -- Periodicals; Nanostructured materials -- Periodicals; Power resources -- Technological innovations -- Periodicals; Nanoscience; Nanostructured materials; Nanotechnology; Power resources -- Technological innovations; Periodicals; 621.042
• DOI: 10.1016/j.nanoen.2016.08.005
• Languages: English
• ISSNs: 2211-2855

Abstract

Abstract: Three easily accessible diketopyrrolopyrrole (DPP)-based small molecular electrolytes (SMEs) with different counter anions (CAs), such as bromide, tetrafluoroborate, and tetraphenylborate, namely DPPN-Br, DPPN-BF4, and DPPN-BPh4, respectively, were synthesized to function as a cathode buffer layer for improving the performance of polymer solar cells. Intriguingly, a strong CA size dependence of self-doping was observed in the SMEs. More interestingly, a tunable dipoles were achieved on the ITO surface modified with electrolytes by simply varying the size of CAs, as verified by the significantly reduced effective work function ( Φ eff ). These n-type self-doped electrolytes possessed a higher electron mobility and created Ohmic contact between the ITO and active layer. Notably, an improved power conversion efficiencies (PCE) of 9.0% was achieved in the device with DPPN-BPh4 interlayer. Graphical abstract: Highlights: Counterion dependence of n-type self-doping interfacial dipoles was fine-tuned. Combination of electron mobility and energy alignment was improved. Polymer solar cells with a power conversion efficiency of 9% were obtained.