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Pressure-Tuned Quantum Well Configuration in Two-Dimensional PA8Pb5I18 Perovskites for Highly Efficient Yellow Fluorescence

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journal contribution
posted on 25.08.2021, 19:13 authored by Yongfu Liang, Min Wu, Can Tian, Xiaoli Huang, Yanping Huang, Yulia Lekina, Ze Xiang Shen, Xinyi Yang
Yellow fluorescent materials (emitting at wavelengths 580–595 nm) offer outstanding functionality for vivid displays, high-density information storage, and high-pressure lighting, especially in white-light-emitting diodes. Currently, the deliberate design of yellow phosphors with high photoluminescence quantum yields (PLQYs) is a developing field. Herein, we report high yellow emission in two-dimensional (2D) halide PA8Pb5I18 (PA = C3H7NH3) perovskite that shows over 80-fold enhancement of their PL under pressure. At an applied pressure of 3.5 GPa, PA8Pb5I18 produces a high PLQY of 77.0% and a color coordinate (0.55, 0.44) closely approaching the standard sodium yellow light (0.575, 0.424). Structural and optical measurements reveal that pressure-induced tilt of the octahedra along the I4I2 axis is attributable to the deepening of trap states in the quantum well structures, leading to a significant Stokes shift. The resulting more localized excitons have a lower probability of scattering with defects, which results in significant suppression of nonradiative loss and promotion of radiative recombination rate, accounting for the efficient and high-color-purity emission. Our findings represent a deep insight into the photophysical nature of 2D halide perovskites, thus offering a promising strategy for the rational design of high-efficiency yellow phosphors.