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

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 PA(8)Pb(5)I(18) (PA = C3H7NH3) perovskite that shows over 80-fold enhancement of their PL under pressure. At an applied pressure of 3.5 GPa, PA(8)Pb(5)I(18) 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 I-4-I-2 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.

Automated summary

This study demonstrates high yellow emission in two-dimensional halide perovskites under pressure, achieving high PLQY and color coordinates close to standard sodium yellow light. The pressure-induced tilting of octahedra enhances trap states, leading to more localized excitons with lower scattering probability, resulting in significant suppression of nonradiative loss and promotion of radiative recombination rate for efficient and high-color-purity emission.