Strontium Ion B‐Site Substitution for Spectral‐Stable Blue Emitting Perovskite Light‐Emitting Diodes

Abstract Halide perovskites are promising emitters for light‐emitting diodes (LEDs) due to their outstanding optoelectronic properties, i.e., tunable bandgap, high photoluminescence quantum efficiency, and excellent color purity. However, in contrast to their green and red cousins, the present blue perovskite LEDs are still suffering from poor operational lifetime and electroluminescence shift during bias operation, hindering their practical applications in full‐color information displays. Developing rational strategies to achieve efficient and stable blue perovskite LEDs is one of the urgent tasks in this community. Herein, through substituting the Pb site with strontium ions, blue perovskite films with stable emission under relatively harsh working conditions, i.e., high electrical bias, constant thermal heating, and UV illumination, are obtained, which accordingly guarantees spectrally stable blue perovskite LEDs with external quantum efficiency of 4.1%. Moreover, different alkaline‐earth metal ions are also investigated to further explore the effects of B‐site ion substitution on the performance of perovskite LEDs. This work demonstrates an alternative path for the development of spectral‐stable blue perovskite LEDs.