Stability-limiting heterointerfaces of perovskite photovoltaics

• Published in: Nature (London) Vol. 605; no. 7909; pp. 268 - 273
• Main Authors: Tan, Shaun, Huang, Tianyi, Yavuz, Ilhan, Wang, Rui, Yoon, Tae Woong, Xu, Mingjie, Xing, Qiyu, Park, Keonwoo, Lee, Do-Kyoung, Chen, Chung-Hao, Zheng, Ran, Yoon, Taegeun, Zhao, Yepin, Wang, Hao-Cheng, Meng, Dong, Xue, Jingjing, Song, Young Jae, Pan, Xiaoqing, Park, Nam-Gyu, Lee, Jin-Wook, Yang, Yang
• Format: Journal Article
• Language: English
• Published: England Nature Publishing Group 12.05.2022
• Subjects: Calcium Compounds; Charge injection; Charge materials; Dissimilar materials; Electronic devices; Electronics industry; Microscopy; Optoelectronic devices; Oxides; Perovskites; Photovoltaic cells; Photovoltaics; Semiconductors; Solar cells; SOLAR ENERGY; Surface charge; Surface chemistry; Surface stability; Surface treatment; Titanium; Trends; Work functions
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/s41586-022-04604-5

Optoelectronic devices consist of heterointerfaces formed between dissimilar semiconducting materials. The relative energy-level alignment between contacting semiconductors determinately affects the heterointerface charge injection and extraction dynamics. For perovskite solar cells (PSCs), the heterointerface between the top perovskite surface and a charge-transporting material is often treated for defect passivation to improve the PSC stability and performance. However, such surface treatments can also affect the heterointerface energetics . Here we show that surface treatments may induce a negative work function shift (that is, more n-type), which activates halide migration to aggravate PSC instability. Therefore, despite the beneficial effects of surface passivation, this detrimental side effect limits the maximum stability improvement attainable for PSCs treated in this way. This trade-off between the beneficial and detrimental effects should guide further work on improving PSC stability via surface treatments.