Photoluminescence Enhancement for Efficient Mixed-Halide Blue Perovskite Light- Emitting Diodes

摘要

The development of highly efficient blue perovskite light-emitting diodes(PeLEDs) remains a big challenge, requiring more fundamental investigations.In this work, significant photoluminescence enhancement in mixedhalide blue perovskite films is demonstrated by using a molecule, benzylphosphonicacid, which eventually doubles the external quantum efficiency to6.3% in sky-blue PeLEDs. The photoluminescence enhancement is achievedby forming an oxide-bonded perovskite surface at grain boundaries and suppressingelectron–phonon interaction, which enhances the radiative recombinationrate and reduces the nonradiative recombination rate, respectively.Moreover, severe thermal quenching is observed in the blue perovskite films,which can be explained by a two-step mechanism involving exciton dissociationand electron–phonon interaction. The results suggest that enhancingthe radiative recombination rate and reducing the electron–phonon interaction-induced nonradiative recombination rate are crucial for achieving blueperovskite films with strong emission at or above room temperature.