Color-Stable Mixed-Halide Blue Perovskite Light-Emitting Diodes

Metal halide perovskites have emerged as a highly promising candidate for the advancement of next-generation light-emitting materials owing to their exceptional optoelectronic properties, including superior color purity, high photoluminescence quantum efficiency, and facile tunability of their bandgap through facile compositional control. As a consequence of these advantages, efficient perovskite light-emitting diodes (PeLEDs) with external quantum efficiency (EQE) surpassing 20% have been successfully demonstrated. However, the realization of efficient and stable blue-emitting PeLEDs, which are crucial for achieving vivid emission across the entire color gamut, has proved to be a formidable challenge, primarily due to the spectral instability exhibited by mixed-halide composites employed for blue emission. In this investigation, we present the successful realization of color-stable mixed-halide blue PeLEDs achieved through the implementation of core/shell perovskite nanograins with mitigated halide segregation. By employing shell materials that effectively bind at the grain boundaries, we effectively suppress the electric-field-induced segregation of halide ions, resulting in stable and narrow emission spectra during the operational lifetime of the devices. Our study thus presents a promising strategy for the realization of stable mixed-halide perovskite materials with complete suppression of halide segregation, thereby facilitating the development of bandgap-tunable perovskite optoelectronic devices.