Targeted elimination of tetravalent-Sn-induced defects for enhanced efficiency and stability in lead-free NIR-II perovskite LEDs.

Guan, Xiang; Li, Yuqing; Meng, Yuanyuan; Wang, Kongxiang; Lin, Kebin; Luo, Yujie; Wang, Jing; Duan, Zhongtao et al. · Nat Commun · 2024

basic_science · Level V

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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 Sn<sup>2+</sup> to oxidize, resulting in detrimental Sn<sup>4+</sup>-induced defects and compromised device performance. Here, we present a targeted strategy to eliminate Sn<sup>4+</sup>-induced defects through moisture-triggered hydrolysis of tin tetrahalide, without degrading Sn<sup>2+</sup> in the CsSnI<sub>3</sub> film. During the moisture treatment, tin tetrahalide is selectively hydrolyzed to Sn(OH)<sub>4</sub>, 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.