Defect precise management enhances the efficiency and electroluminescence color stability of blue perovskite light-emitting diodes

Abstract

Metal halide perovskites (MHPs) exhibit promising potential in lighting and display applications owing to their advantages of tunable emission colors, high color purity, and solution processability. However, progress in blue perovskite light-emitting diodes (PeLEDs) has not kept pace with advances in green and red devices. High defect density and ion migration are the primary factors limiting the efficiency improvement and spectral stability of blue PeLEDs. In this work, two functional additives were introduced to precisely manage defects in perovskite films, resulting in blue PeLEDs with high efficiency and spectral stability. Specifically, the bis(2-(diphenylphosphino)phenyl)ether oxide (DPEPO) can coordinate with uncoordinated Pb²⁺. Meanwhile, guanidinium hydrobromide (GABr) compensates for halide vacancies and suppresses halide phase segregation in CsPb(Br_x/Cl_1−x)₃ through hydrogen bonding or ionic bonding, thereby stabilizing the device's electroluminescence (EL) spectrum. As a result, under the synergistic modulation of DPEPO and GABr, the perovskite films exhibit enhanced crystallinity and reduced defect density. The modified pure-blue device achieves a maximum external quantum efficiency of 3.53% (vs. 1.82% for the control), a maximum power efficiency of 2.49 lm W⁻¹ (vs. 1.43 lm W⁻¹), and a maximum current efficiency of 2.78 cd A⁻¹ (vs. 1.67 cd A⁻¹). Moreover, the EL spectrum remains stable at 476 nm. This work proposes a viable strategy for developing high-efficiency and stable blue PeLEDs.