Mn 2+ ‐Doped CsPbI 3 Nanocrystals for Perovskite Light‐Emitting Diodes with High Luminance and Improved Device Stability

Abstract

Cubic α-CsPbI3 has promising applications in the optoelectronic field for its excellent properties. However, the α-CsPbI3 black phase is instable at room temperature and easily converts into non-luminescent yellow orthorhombic phase (δ-CsPbI3). Herein, the stability of α-CsPbI3 is significantly improved by incorporating Mn2+ dopants into the perovskite lattice. The Mn2+: CsPbI3 has essentially the same crystal structure as the parent α-CsPbI3, and Mn2+ doping can promote photoluminescence quantum yield (PLQY) from 55% to 93%. Importantly, the Mn2+: CsPbI3 can maintain 60% PLQY after exposing in air for 45 days, while the un-doped CsPbI3 completely loses its luminescence in 10 days. First-principles calculations testify that the improved stability and optical properties of Mn2+: CsPbI3 are primarily attributed to the increased formation energy and tolerance factor. Accordingly, the luminance, external quantum efficiency (EQE) and T50 lifetime of Mn2+: CsPbI3 PeLED reach 1066 cd/m2, 1.8% and 2500 s, while the values for the un-doped counterpart are only 415 cd/m2, 0.6%, and 140 s, respectively. In addition, it is evidenced that introducing a LiF buffer layer between hole transport layer and perovskite emissive layer can further boost the device performance, particularly, the luminance and T50 lifetime achieve1394 cd/m2 and 225 min at 140 cd/m2.This article is protected by copyright. All rights reserved.