Trap-Filling of ZnO Buffer Layer for Improved Efficiencies of Organic Solar Cells

Mingguang Li; Jing Li; Longsheng Yu; Ying Zhang; Yizhong Dai; Runfeng Chen; Wei Huang

doi:10.3389/fchem.2020.00399

Trap-Filling of ZnO Buffer Layer for Improved Efficiencies of Organic Solar Cells

Front Chem. 2020 May 26:8:399. doi: 10.3389/fchem.2020.00399. eCollection 2020.

Authors

Mingguang Li¹, Jing Li¹, Longsheng Yu¹, Ying Zhang¹, Yizhong Dai¹, Runfeng Chen¹, Wei Huang^{1

2}

Affiliations

¹ Key Laboratory for Organic Electronics and Information Displays & Jiangsu Key Laboratory for Biosensors, Institute of Advanced Materials (IAM), Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing University of Posts & Telecommunications, Nanjing, China.
² Institute of Flexible Electronics, Northwestern Polytechnical University, Xi'an, China.

Abstract

Trap-assisted recombination loss in the cathode buffer layers (CBLs) is detrimental to the electron extraction process and severely restricts the power conversion efficiencies (PCEs) of organic solar cells (OSCs). Herein, a novel organic-inorganic hybrid film composed of zinc oxide (ZnO) and 2,3,5,6-tetrafluoro-7,7,8, 8-tetracyanoquinodimethane (F4TCNQ) is designed to fill the intrinsic charge traps of ZnO-based CBLs by doping F4TCNQ for high-performance inverted OSCs. Thus, constructed ZnO:F4TCNQ hybrid film exhibits enhanced surface hydrophobicity and adjustable energy levels, providing favorable interfacial condition for electron extraction process. Consequently, trap-assisted recombination loss in the CBLs was efficiently suppressed, leading to the significantly improved fill factor and PCEs of both fullerene- and non-fullerene-based OSCs using the ZnO:F4TCNQ hybrid CBLs. This work illustrates a convenient organic acceptor doping approach to suppress the internal charge traps of traditional inorganic CBLs, which will shed new light on the fabrication of high-performance CBLs with facile electron extraction processes in inverted OSC devices.

Keywords: ZnO; cathode buffer layers; organic solar cells; organic–inorganic hybrid film; trap-filling.