Unique Energy Alignments of a Ternary Material System toward High-Performance Organic Photovoltaics

Pei Cheng; Jiayu Wang; Qianqian Zhang; Wenchao Huang; Jingshuai Zhu; Rui Wang; Sheng-Yung Chang; Pengyu Sun; Lei Meng; Hongxiang Zhao; Hao-Wen Cheng; Tianyi Huang; Yuqiang Liu; Chaochen Wang; Chenhui Zhu; Wei You; Xiaowei Zhan; Yang Yang

doi:10.1002/adma.201801501

Unique Energy Alignments of a Ternary Material System toward High-Performance Organic Photovoltaics

Adv Mater. 2018 Jul;30(28):e1801501. doi: 10.1002/adma.201801501. Epub 2018 May 21.

Authors

Pei Cheng¹, Jiayu Wang², Qianqian Zhang³, Wenchao Huang^{1

4}, Jingshuai Zhu², Rui Wang¹, Sheng-Yung Chang¹, Pengyu Sun¹, Lei Meng¹, Hongxiang Zhao^{1

4}, Hao-Wen Cheng^{1

4}, Tianyi Huang¹, Yuqiang Liu^{1

4}, Chaochen Wang¹, Chenhui Zhu⁵, Wei You³, Xiaowei Zhan², Yang Yang^{1

4}

Affiliations

¹ Department of Materials Science and Engineering, University of California, Los Angeles, CA, 90095, USA.
² Department of Materials Science and Engineering, College of Engineering, Key Laboratory of Polymer Chemistry and Physics of Ministry of Education, Peking University, Beijing, 100871, P. R. China.
³ Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA.
⁴ California NanoSystems Institute, University of California, Los Angeles, CA, 90095, USA.
⁵ Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.

PMID: 29782685
DOI: 10.1002/adma.201801501

Abstract

Incorporating narrow-bandgap near-infrared absorbers as the third component in a donor/acceptor binary blend is a new strategy to improve the power conversion efficiency (PCE) of organic photovoltaics (OPV). However, there are two main restrictions: potential charge recombination in the narrow-gap material and miscompatibility between each component. The optimized design is to employ a third component (structurally similar to the donor or acceptor) with a lowest unoccupied molecular orbital (LUMO) energy level similar to the acceptor and a highest occupied molecular orbital (HOMO) energy level similar to the donor. In this design, enhanced absorption of the active layer and enhanced charge transfer can be realized without breaking the optimized morphology of the active layer. Herein, in order to realize this design, two new narrow-bandgap nonfullerene acceptors with suitable energy levels and chemical structures are designed, synthesized, and employed as the third component in the donor/acceptor binary blend, which boosts the PCE of OPV to 11.6%.

Keywords: energy level alignments; fullerene-free; nonfullerene; organic solar cells; ternary blends.