Spectrally stable blue electroluminescence of mixed-halide perovskite light-emitting diodes featuring ion migration inhibition

Perovskites light emitting diodes (PeLEDs) are promising candidates for next-generation display devices because of their attractive properties of low-cost, solution processability and excellent color purity. For metal halide perovskite materials, the emission tuning can be easily achieved by altering halide composition. However, blue PeLEDs with chlorine incorporation usually suffer from the severe phase segregation and ion migration, resulting in the red-shifted electroluminescence and the efficiency degradation. Here, the partial substitution of Pb²⁺ ions with non-toxic Sr²⁺ is adopted to enhance the formation energy of Sr-alloyed perovskite films, leading to the negligible electroluminescence in electrically driven blue PeLEDs. The maximum brightness and efficiency are optimized simultaneously. Further, such a substitution can greatly enhance the thermal and operational stabilities of PeLEDs.