Graded bulk-heterojunction enables 17% binary organic solar cells via nonhalogenated open air coating

Ying Zhang; Kuan Liu; Jiaming Huang; Xinxin Xia; Jiupeng Cao; Guangming Zhao; Patrick W K Fong; Ye Zhu; Feng Yan; Yang Yang; Xinhui Lu; Gang Li

doi:10.1038/s41467-021-25148-8

Graded bulk-heterojunction enables 17% binary organic solar cells via nonhalogenated open air coating

Nat Commun. 2021 Aug 10;12(1):4815. doi: 10.1038/s41467-021-25148-8.

Authors

Ying Zhang¹, Kuan Liu², Jiaming Huang¹, Xinxin Xia³, Jiupeng Cao⁴, Guangming Zhao⁴, Patrick W K Fong¹, Ye Zhu⁴, Feng Yan⁴, Yang Yang⁵, Xinhui Lu³, Gang Li⁶

Affiliations

¹ Department of Electronic and Information Engineering, Research Institute for Smart Energy (RISE), The Hong Kong Polytechnic University, Hong Kong, China.
² Department of Electronic and Information Engineering, Research Institute for Smart Energy (RISE), The Hong Kong Polytechnic University, Hong Kong, China. kuan-lk.liu@polyu.edu.hk.
³ Department of Physics, The Chinese University of Hong Kong, Hong Kong, China.
⁴ Department of Applied Physics, The Hong Kong Polytechnic University, Hong Kong, China.
⁵ Department of Materials Science and Engineering, UCLA, Los Angeles, CA, USA.
⁶ Department of Electronic and Information Engineering, Research Institute for Smart Energy (RISE), The Hong Kong Polytechnic University, Hong Kong, China. gang.w.li@polyu.edu.hk.

Abstract

Graded bulk-heterojunction (G-BHJ) with well-defined vertical phase separation has potential to surpass classical BHJ in organic solar cells (OSCs). In this work, an effective G-BHJ strategy via nonhalogenated solvent sequential deposition is demonstrated using nonfullerene acceptor (NFA) OSCs. Spin-coated G-BHJ OSCs deliver an outstanding 17.48% power conversion efficiency (PCE). Depth-profiling X-ray photoelectron spectroscopy (DP-XPS) and angle-dependent grazing incidence X-ray diffraction (GI-XRD) techniques enable the visualization of polymer/NFA composition and crystallinity gradient distributions, which benefit charge transport, and enable outstanding thick OSC PCEs (16.25% for 300 nm, 14.37% for 500 nm), which are among the highest reported. Moreover, the nonhalogenated solvent enabled G-BHJ OSC via open-air blade coating and achieved a record 16.77% PCE. The blade-coated G-BHJ has drastically different D-A crystallization kinetics, which suppresses the excessive aggregation induced unfavorable phase separation in BHJ. All these make G-BHJ a feasible and promising strategy towards highly efficient, eco- and manufacture friendly OSCs.

Abstract

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