Sequential structural degradation of red perovskite quantum dots and its prevention by introducing iodide at a stable gradient concentration into the core–shell red perovskite quantum dots

Abstract

Perovskite quantum dots (QDs) have been extensively studied as emissive materials for next-generation optoelectronics due to their outstanding optical properties; however, their structural instabilities, specifically those of red perovskite QDs, are critical obstacles in realizing operationally reliable perovskite QD-based optoelectronic devices. Accordingly, herein, we investigated the sequential degradation mechanism of red perovskite QDs upon their exposure to an electric field. <i>Via</i> electrical and chemical characterization, we demonstrated that degradation occurred in the following order: anion-defect-assisted halide migration, cation-defect-assisted migration of I^-/Cs⁺ ions, defective gradient I ion distribution, structural distortion, and ion transport/I₂ vaporization with defect proliferation. Among these steps, the defective gradient I ion distribution is the key process in the structural degradation of perovskite QDs. Based on our findings, we designed perovskite/SiO₂ core-shell QDs with stable gradient I concentrations. Most notably, the operational stabilities of perovskite QD-light-emitting diodes (PeLEDs) fabricated using the perovskite/SiO₂ core-shell QDs were approximately 5000 times those of the PeLEDs constructed using pristine perovskite QDs.