Tuning of Optical Emission Colors in a Single Dion–Jacobson 2D Perovskite Microcrystal via Defect Engineering

Developing multicolor‐tunable semiconductors is critical for next‐generation displays. Up to date, achieving the color tunability within a fixed‐composition material without employing any doping strategy remains a persistent scientific challenge. Herein, we demonstrate an innovative and facile method to attain a dual‐color emission function in a single Dion‐Jacobson (D‐J) perovskite microcrystal (MC) via the lattice strain engineering, which artificially introduces deep‐level defects as radiative centers. The rich and reversible color tuning from cyan to pink are accomplished via a precise control of the intrinsic excitonic to deep‐level defect luminescence balance by adjusting either the incident power or repetition rate of the excitation laser source. These findings pioneer a novel approach to the color modulations in a single‐crystal structure, establishing 2D perovskites as highly promising candidates for future display technologies.