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

• Published in: Journal of materials chemistry. C, Materials for optical and electronic devices Vol. 11; no. 29; pp. 9916 - 9924
• Main Authors: Ma, Zong-Guang, Shen, Yang, Zhang, Kai, Cao, Long-Xue, Ren, Hao, Chen, Wei-Shuo, Wei, Huai-Xin, Li, Yan-Qing, Kera, Satoshi, Tang, Jian-Xin
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 27.07.2023
• Subjects: Crystallization; Lead free; Lead oxides; Light emitting diodes; Morphology; Oxidation; Perovskites; Red lead; Strong interactions (field theory); Tin; Toxicity
• ISSN: 2050-7526; 2050-7534
• DOI: 10.1039/d3tc01743e

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 Sn 2+ and poor perovskite morphology. In this work, bifunctional additive engineering by incorporating nicotinohydrazide (NHD) with two effective groups (-N 2 H 3 and -C&z.dbd;O) into the perovskite is employed for improving the device performance of Sn-based PeLEDs. The Sn 2+ oxidation is greatly suppressed due to the reducibility of -N 2 H 3 and strong interaction between -C&z.dbd;O and Sn 2+ . 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. Inhibition of the Sn 2+ oxidation process and reduction of perovskite crystallization rate are achieved simultaneously by using bifunctional small molecular additives, yielding a red-emission device with CIE coordinates matching the BT.2020 standard.