Ternary organic solar cells based on ZnO-Ge double electron transport layer with enhanced power conversion efficiency. (October 2017)

• Record Type: Journal Article
• Authors: Li, Chang; Sun, Xiaoxiang; Ni, Jian; Huang, Like; Xu, Rui; Li, Zhenglong; Cai, Hongkun; Li, Juan; Zhang, Yaofang; Zhang, Jianjun
• Is Part Of: Solar energy. Volume 155(2017)
• Page Start: 1052
• Page End: 1058
• Publication Date: 2017-10
• Subjects: Ternary organic solar cells -- Inverted structure -- Electron transport layer -- ZnO-Ge bilayer; Solar energy -- Periodicals; Solar engines -- Periodicals; 621.47
• DOI: 10.1016/j.solener.2017.07.053
• Languages: English
• ISSNs: 0038-092X

Abstract

Graphical abstract: In this article, we first report the inverted ternary OSCs based on ZnO-Ge double ETL. By introducing the additional Ge layer, the device performance was significantly increased to 9.15%, which exhibited a 18.4% improvement compared to that of the device using ZnO-only ETL. Highlights: ZnO-Ge bilayer was employed as ETL in inverted ternary organic solar cells. Improved energy level alignment and interfacial contact between the active layer and ETL. Enhanced optical transmittance and perpendicular electrical transport properties. Facilitated charge transfer from the active layer to ETL. This results in an increased PCE from 7.73% to 9.15%. Abstract: A ZnO-Ge bilayer was proposed as an electron transport layer (ETL) in inverted ternary organic solar cells (OSCs). The energy level alignment, surface morphology, optical and electrical properties, and interface charge transfer were investigated to understand the impact of the additional Ge NPs layer. The results indicated that apart from improving the energy level alignment, the Ge NPs layer optimizes the interfacial contact between the active layer and ETL. Moreover, the ZnO-Ge bilayer shows better optical transmittance and perpendicular electrical transport properties compared to that of ZnO NPs layer. Benefit from the enhanced charge transfer from the active layer to ETL, the champion power conversion efficiency (PCE) was significantly increased to 9.15% by introducing the additional Ge layer, which exhibited a 18.4% improvement compared to that of the ZnO-only devices. Our results demonstrated the feasibility of ZnO-Ge bilayer as the ETL for high-performance OSCs.