Blue Light-Emitting Diodes Based on Pure Bromide Perovskites.

Blue perovskite light-emitting diodes (LEDs) are essential for the creation of full-color displays and white-light illumination, and some significant progress is made in recent years. However, most high-performance blue perovskite LEDs are currently based on mixed-halide perovskites and suffer from unstable spectra due to inevitable halide phase segregation, which is unfavorable for the application of blue perovskite LEDs. In contrast, blue emissions from pure bromide perovskites generally exhibit stable spectra (consistent emission peak positions and spectral shapes) and are worthy of attention. In this review, the recent advances in blue LEDs based on pure bromide perovskites according to different strategies are classified and summarized. Moreover, the challenges related to poor charge injection, high defect-state density, lack of high-performance in the deeper blue region, and inferior operational stability are addressed. Finally, an outlook is provided on feasible future research directions for highly bright, efficient, and stable blue perovskite LEDs.