Post‐Passivation of Perovskite Quantum Dots by Conjugated Molecules for Spectrally Stable and Efficient Deep Blue Light‐Emitting Diodes

Abstract Perovskite light‐emitting diodes (PeLEDs) are promising candidates for displays and solid‐state lighting due to their tunable colors, high conversion efficiency, and low cost. However, the performance of deep blue PeLEDs lags far behind that of near‐infrared, red, and green ones. Here, the ligand concentration on the perovskite surface is regulated by introducing a small organic molecule 3‐(5,9‐dioxa‐13b‐boranaphtho [3,2,1‐d,e] anthracene‐7‐yl)‐9‐phenyl‐9H‐carbazole (BOCzPh) to reduce the defects in the mixed‐halogen perovskite lattice and improve the exciton binding energy of perovskite quantum dots (QDs). Finally, deep blue PeLEDs with an emission peak at 469 nm, a peak external quantum efficiency of 2.8%, and a maximum brightness of 851 cd m −2 are obtained. Owing to the post‐passivation of QDs by BOCzPh molecules, the emission spectra of the mixed‐halide perovskites are stabilized and the luminous efficiency of the devices is improved simultaneously. This work provides a new approach to realize spectrally stable and efficient deep blue PeLEDs.