Improved exciton photoluminescence of Zn-doped quasi-2D perovskite nanocrystals and their application as luminescent materials in light-emitting devices

Abstract

In this paper, we report Zn-doped quasi-two-dimensional (Q-2D) perovskite nanocrystals (NCs). The incorporation of Zn²⁺ cations can passivate the Pb²⁺ vacancy defect states on the NC surface, thus suppressing trap-assisted nonradiative recombination. At an optimal Zn loading ratio of 20%, Zn-doped Q-2D NCs showed the best photoluminescence quantum yield (PLQY) of 43.6% and increased photoluminescence (PL) lifetime due to the significantly reduced nonradiative recombination rate. Temperature-dependent PL spectra demonstrate the negative thermal quenching behavior of NCs, and Zn-doped Q-2D NCs exhibit larger exciton binding energy than the pristine NCs. The excitonic PL properties of Zn-doped Q-2D NCs were characterized by the efficient energy funneling process from low-n to high-n phases. Furthermore, a 2.25-fold PL emission enhancement was observed for the Zn-doped Q-2D NCs/Al film, which can be attributed to the increased radiative recombination rate induced by surface plasmon coupling. Owing to the excellent PL properties and stability of Zn-doped Q-2D NCs, a green light-emitting device is achieved by integrating Zn-doped Q-2D NCs on a blue LED chip (460 nm). Our results reveal the photophysical properties of Q-2D perovskite NC materials and indicate their potential applications in light-emitting devices.