Preferentially coordinating tin ions to suppress composition segregation for high-performance tin-lead mixed perovskite solar cells

• Published in: Nano energy Vol. 131; p. 110248
• Main Authors: Chen, Guocong, Su, Gangsen, Zhang, Xusheng, Sun, Qiang, Gao, Han, Liu, Kaiyuan, Li, Hao, Wang, Jiafeng, He, Dong, Ma, Guoqiang, Niu, Zeyu, Cheng, Tianle, Li, Zhaoning, Slater, Peter Raymond, He, Zhubing
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.12.2024
• Subjects: Balanced crystallization; Composition segregation; Homogeneous Sn/Pb distribution; Tin-lead mixed perovskite solar cells; Homogeneous Sn/Pb distribution; Balanced crystallization; Tin-lead mixed perovskite solar cells; Composition segregation
• ISSN: 2211-2855
• DOI: 10.1016/j.nanoen.2024.110248

Tin-lead mixed perovskites (TLPs) with a tunable and ideal bandgap exhibit great potential in approaching the Shockley–Queisser limit of power conversion efficiency (PCE). However, two critical issues are necessary to be addressed, including the oxidation of Sn2+ and negligible composition and phase segregation. The latter derives from the unbalanced crystallization rate between Sn- and Pb-based perovskites. Here, we report a strategy to address the above critical issues by introducing 3,4-Dihydroxybenzylamine hydrobromide (DHBABr) in the TLP precursor solution. DHBABr was revealed to promote the crystallization of FAPbI3 perovskite by suppressing the formation of crystalline DMSO-FA-Pb-I intermediates and retard the crystallization rate of FASnI3 by preferentially forming a steady amorphous DHBA-FA-Sn-I intermediate. This, therefore, balances the crystallization rate between Sn- and Pb-based perovskites. As a result, the spatial distribution of Sn/Pb ratio is much more uniform across the whole TLP film, which benefits the upscaling of the manufacturing process. Relying on this doping strategy accompanied by the surface passivation with DHBABr, which reduces the defect density of TLP, inhibits the oxidation of Sn2+, and optimizes the band alignment of the device, we have achieved a PCE of 22.44 % with Voc of 0.853 V and FF of 80.0 %, along with an enhanced long-term stability of T80 = 476 h under continuously light illumination in the champion device. [Display omitted] •Balanced crystallization rate of Sn- and Pb-based perovskites in mixed tin-lead perovskite was realized by DHBABr doping.•Homogeneous Sn/Pb distribution derived from the balanced crystallization was demonstrated through ICP-MS, XPS depth profile, and TEM-EDS measurements.•High PCE of 22.44 % was achieved in mixed tin-lead perovskite solar cells.