Targeted elimination of tetravalent-Sn-induced defects for enhanced efficiency and stability in lead-free NIR-II perovskite LEDs
Xiang Guan, Yuqing Li, Yuanyuan Meng, Kongxiang Wang, Kebin Lin, Yujie Luo, Jing Wang, Zhongtao Duan, Hong Liu, Yang Liu, Lingfang Zheng, Junpeng Lin, Yalian Weng, Fengxian Xie, Jianxun Lu, Zhanhua Wei
Abstract
Eco-friendly Sn-based perovskites show significant potential for high-performance second near-infrared window light-emitting diodes (900 nm – 1700 nm). Nevertheless, achieving efficient and stable Sn-based perovskite second near-infrared window light-emitting diodes remains challenging due to the propensity of Sn2+ to oxidize, resulting in detrimental Sn4+-induced defects and compromised device performance. Here, we present a targeted strategy to eliminate Sn4+-induced defects through moisture-triggered hydrolysis of tin tetrahalide, without degrading Sn2+ in the CsSnI3 film. During the moisture treatment, tin tetrahalide is selectively hydrolyzed to Sn(OH)4, which provides sustained protection. As a result, we successfully fabricate second near-infrared window light-emitting diodes emitting at 945 nm, achieving a performance breakthrough with an external quantum efficiency of 7.6% and an operational lifetime reaching 82.6 h. Guan et al. report a strategy of moisture-triggered selective hydrolysis of Sn4+ into Sn(OH)4, eliminating Sn4 + -induced defects in tin-based perovskites and enhancing the electron injection in NIR-II LED devices with peak emission of 945 nm and external quantum efficiency of 7.6%.