Melt‐Quenched CsPbBr 3 Perovskites with Bright Orange Defect Emission

ABSTRACT Defect emission, as a fundamental phenomenon in semiconductor physics, enables multifaceted applications in solid‐state lighting, anti‐counterfeiting data storage, and quantum information technologies. Lead halide perovskites can accommodate native defects without nonradiative quenching of band‐edge emission, yet intentionally creating and observing radiative defect centers in these materials has proved challenging. Here, we report the observation of stable defect‐induced emission featuring bright orange luminance peaked at ∼601 nm and prolonged carrier lifetimes of ∼154.69 µs in cesium lead bromide perovskites. This unique behavior is achieved by the introduction of extreme residual stress through a cryogenic melt‐quenching strategy. Density functional theory calculations show that strain alters the formation energy of bromine vacancies, thereby accounting for the redshifted emission and high density of radiative defects. Moreover, modulation of the quenching rate allows for deliberate engineering of the residual stress, thereby realizing the precise manipulation of the balance of band edge and defect emissions. The manifestation of defect luminescence in metal halide perovskites harbors promising prospects for innovative applications in optoelectronics, bioimaging, and solid‐state qubits.