Regulated crystallization with minimized degradation for pure-red lead-free perovskite light-emitting diodes

Reducing the lead (Pb) toxicity has remained a huge challenge toward the commercial development of the mainstream Pb-based halide perovskites. Tin (Sn) has been considered as one of the most promising candidates to replace the Pb component, but it still suffers from severe oxidation of Sn2+ and poor perovskite morphology. In this work, bifunctional additive engineering by incorporating nicotinohydrazide (NHD) with two effective groups (-N2H3 and -C=O) into the perovskite is employed for improving the device performance of Sn-based PeLEDs. The Sn2+ oxidation is greatly suppressed due to the reducibility of -N2H3 and strong interaction between -CO and Sn2+. Meanwhile, the perovskite film morphology is apparently optimized owing to the distinctly retarded crystallization process. Consequently, a pure-red PeLED emitting at 628 nm is achieved with elevated electroluminescence efficiency and stability, and the CIE coordinates match the BT.2020 standard. These results provide an effective strategy for the development of lead-free PeLEDs.

Automated summary

In this study, bifunctional additive engineering using nicotinohydrazide (NHD) with two effective groups (-N2H3 and -C=O) was employed to improve the performance of tin-based PeLEDs. The oxidation of Sn2+ was suppressed and the perovskite morphology was optimized, leading to the achievement of a pure-red PeLED emitting at 628 nm with elevated electroluminescence efficiency and stability. The results provide an effective strategy for the development of lead-free PeLEDs.