Efficient and stable inverted perovskite solar cells enabled by inhibition of self-aggregation of fullerene electron-transporting compounds

Chengbo Tian; German Betancourt-Solis; Ziang Nan; Kaikai Liu; Kebin Lin; Jianxun Lu; Liqiang Xie; Luis Echegoyen; Zhanhua Wei

doi:10.1016/j.scib.2020.08.041

Efficient and stable inverted perovskite solar cells enabled by inhibition of self-aggregation of fullerene electron-transporting compounds

Sci Bull (Beijing). 2021 Feb 26;66(4):339-346. doi: 10.1016/j.scib.2020.08.041. Epub 2020 Sep 1.

Authors

Chengbo Tian¹, German Betancourt-Solis², Ziang Nan³, Kaikai Liu⁴, Kebin Lin⁴, Jianxun Lu⁴, Liqiang Xie⁴, Luis Echegoyen⁵, Zhanhua Wei⁶

Affiliations

¹ Institute of Luminescent Materials and Information Displays, College of Materials Science and Engineering, Huaqiao University, Xiamen 361021, China. Electronic address: cbtian@hqu.edu.cn.
² Department of Chemistry, University of Texas at El Paso, El Paso, TX 79968, USA.
³ iChEM (Collaborative Innovation Center of Chemistry for Energy Materials), Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China.
⁴ Institute of Luminescent Materials and Information Displays, College of Materials Science and Engineering, Huaqiao University, Xiamen 361021, China.
⁵ Department of Chemistry, University of Texas at El Paso, El Paso, TX 79968, USA. Electronic address: echegoyen@utep.edu.
⁶ Institute of Luminescent Materials and Information Displays, College of Materials Science and Engineering, Huaqiao University, Xiamen 361021, China. Electronic address: weizhanhua@hqu.edu.cn.

PMID: 36654413
DOI: 10.1016/j.scib.2020.08.041

Abstract

Fullerene-based electron-transporting layers (ETLs) significantly influence the defect passivation and device performance of inverted perovskite solar cells (PSCs). However, the π-cage structures of fullerenes lead to a strong tendency to self-aggregate, which affects the long-term stability of the corresponding PSCs. Experimental results revealed that [6,6]-phenyl-C₆₁-butyric acid methyl ester (PCBM)-based ETLs exhibit a certain degree of self-aggregation that affects the stability of the device, particularly under continuous irradiation stress. To modulate the aggregation behavior, we replaced a methyl hydrogen of PCBM with a phenyl group to yield [6,6]-phenyl-C₆₁-butyric acid benzyl ester (PCBB). As verified through X-ray crystallography, this minor structural modification results in more non-covalent intermolecular interactions, which effectively enhanced the electron-transporting ability of the PCBB-based ETL and led to an efficiency approaching 20%. Notably, the enhanced intermolecular forces of PCBB suppressed its self-aggregation, and the corresponding device showed significantly improved stability, retaining approximately 90% of its initial efficiency after 600 h under one-sun irradiation with maximum power point tracking. These findings provide a viable approach for the design of new fullerene derivatives to tune their intermolecular interactions to suppress self-aggregation within the ETL for high-performance PSCs.

Keywords: Functionalized fullerene; Intermolecular interaction; Inverted perovskite solar cells; Operation stability; Self-aggregation.