Manganese Doped Tin Oxide for Stable and Efficient Quantum Dot Light-Emitting Diodes

As an alternative electron transport material to the chemically unstable ZnO nanoparticles (NPs), SnO2 NPs exhibit a great potential to construct high-performance quantum dot light-emitting diodes (QLEDs). However, only moderate device performance has been obtained for SnO2-based QLEDs due to the low electron mobility, unfavorable energy band, and massive defects of SnO2 NPs. Herein, a strategy of transition metal doping is reported to achieve high-quality manganese-doped SnO2 (Mn-SnO2) NPs to address the above problems. Specifically, the large bond energy of MnO bonds reduces the oxygen vacancy defects, prompting an effective suppression of the interfacial exciton quenching for massive radiative recombination. Moreover, the favorable energy band and high electron mobility for Mn-SnO2 promote efficient electron injection and transportation. The good optoelectronic properties for Mn-SnO2 NPs contribute to a great enhancement in device efficiency from 8.2 to 11.4% and a remarkable improvement in lifetime (T95) from 565.3 to 1009.2 h at 1000 cd-2, among the best performing ZnO-free QLEDs. Notably, the Mn-SnO2 based QLEDs show a very superior shelf stability to the QLEDs based on SnO2 and ZnO analogs. Consequently, this work reports an effective approach to achieve high-quality SnO2 NPs for efficient and stable QLEDs. High-quality manganese-doped SnO2 (Mn-SnO2) NPs are proposed to address the problems of low electron mobility, unfavorable energy band, and massive defects of pure SnO2 NPs. Notably, the Mn-SnO2-based quantum dot light-emitting diodes (QLEDs) show superior shelf stability to the devices based on SnO2 and ZnO analogs, contributing an efficient transport layer for highly-performed QLEDs toward practical applications. image