Improved Carrier Management via a Multifunctional Modifier for High‐Quality Low‐Bandgap Sn–Pb Perovskites and Efficient All‐Perovskite Tandem Solar Cells

• Published in: Advanced materials (Weinheim) Vol. 35; no. 22; pp. e2300352 - n/a
• Main Authors: Luo, Jincheng, He, Rui, Lai, Huagui, Chen, Cong, Zhu, Jingwei, Xu, Yuliang, Yao, Fang, Ma, Tianshu, Luo, Yi, Yi, Zongjin, Jiang, Yiting, Gao, Zhiyu, Wang, Juncheng, Wang, Wenwu, Huang, Hao, Wang, Ye, Ren, Shengqiang, Lin, Qianqian, Wang, Changlei, Fu, Fan, Zhao, Dewei
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 01.06.2023
• Subjects: all‐perovskite tandem solar cells; carrier management; Carrier recombination; Circuits; defect passivation; Diffusion length; Dipoles; Electron transfer; Energy bands; Energy gap; Lead; low‐bandgap perovskites; Materials science; Perovskites; Photovoltaic cells; Production costs; Radiative recombination; Solar cells; Tin; all-perovskite tandem solar cells; carrier management; electron transfer; low-bandgap perovskites; defect passivation
• ISSN: 0935-9648; 1521-4095; 1521-4095
• DOI: 10.1002/adma.202300352

All‐perovskite tandem solar cells (TSCs) hold great promise in terms of ultrahigh efficiency, low manufacturing cost, and flexibility, stepping forward to the next‐generation photovoltaics. However, their further development is hampered by the relatively low performance of low‐bandgap (LBG) tin (Sn)–lead (Pb) perovskite solar cells (PSCs). Improving the carrier management, including suppressing trap‐assisted non‐radiative recombination and promoting carrier transfer, is of great significance to enhance the performance of Sn–Pb PSCs. Herein, a carrier management strategy is reported for using cysteine hydrochloride (CysHCl) simultaneously as a bulky passivator and a surface anchoring agent for Sn–Pb perovskite. CysHCl processing effectively reduces trap density and suppresses non‐radiative recombination, enabling the growth of high‐quality Sn–Pb perovskite with greatly improved carrier diffusion length of >8 µm. Furthermore, the electron transfer at the perovskite/C60 interface is accelerated due to the formation of surface dipoles and favorable energy band bending. As a result, these advances enable the demonstration of champion efficiency of 22.15% for CysHCl‐processed LBG Sn–Pb PSCs with remarkable enhancement in both open‐circuit voltage and fill factor. When paired with a wide‐bandgap (WBG) perovskite subcell, a certified 25.7%‐efficient all‐perovskite monolithic tandem device is further demonstrated. High‐quality Sn–Pb perovskites and excellent contacts at the perovskite/C60 interface are developed by introducing a one‐in‐all modifier. The introduction of cysteine hydrochloride (CysHCl) to Sn–Pb perovskites restrains non‐radiative recombination and facilitates electron transfer. Consequently, the CysHCl‐processed devices achieve the highest power conversion efficiency (PCE) of 22.15% for low‐bandgap (LBG) Sn–Pb perovskite solar cell (PSC) and 26.16% for all‐perovskite monolithic tandem devices.