Suppressing\nDisproportionation Decomposition in Sn-Based\nPerovskite Light-Emitting Diodes

Nontoxic Sn-based perovskite light-emitting diodes (Pero-LEDs)\nhave been developing rapidly in recent years. However, high-quality\nSn-based perovskite films are hardly prepared because of the heavy\nself-doping of Sn⁴⁺ in the as-prepared films. Most previous\nreports indicate that the Sn⁴⁺ formation is mainly attributed\nto the Sn²⁺ oxidation by external oxidizers. Here, for\nthe first time, we reveal that the disproportionation decomposition\nof Sn²⁺ during the annealing process plays a critical role\nin degrading device performance. To resolve this issue, we introduced\nformamidine thiocyanate into the perovskite precursor as a thermal-sacrificial\nagent to alleviate the disproportionation decomposition. Finally,\nwe achieved efficient Pero-LEDs with a maximum external quantum efficiency\nof 5.3% and ultralow efficiency roll-off. This work provides a view\nof understanding the instability of Sn-based perovskite and presents\na practical method to achieve efficient Sn-based Pero-LEDs by suppressing\nthe disproportionation decomposition of Sn²⁺.