Interface and Defect Engineering Strategies toward High-Performance Blue Perovskite Light-Emitting Diodes

Abstract

Perovskite light-emitting diodes (PeLEDs) hold great promise for full-color displays and solid-state lighting due to their high efficiency and low fabrication cost.Among the primary colors, blue PeLEDs lag behind because of intrinsic challenges, including high defect densities in the emissive layer and inefficient interfacial charge transport, which limit device performance. Here, we report a dual-strategy approach combining defect passivation and interface engineering to realize high-efficiency quasi-2D blue PeLEDs. Incorporation of dimethylphosphine oxide (DMPO) into the PPA0.8(Cs0.7FA0.3)1.1Pb(Br0.8Cl0.2)3.9 precursor effectively passivates undercoordinated Pb 2+ sites, reducing trap density by 30.75% and yielding a maximum external quantum efficiency (EQE) of 6.92%. Introducing a propionamide (PAM) interlayer on the hole transport layer further improves film crystallinity, suppresses nonradiative recombination, accelerates the radiative carrier dynamics, and optimizes energy-level alignment for more efficient hole injection. The synergistic combination of DMPO and PAM enhances brightness, efficiency, and operational stability of PeLEDs.Consequently, the optimized quasi-2D sky-blue PeLEDs achieve a maximum luminance of 2135 cd/m 2 and a peak EQE of 12.94% at the electroluminescence (EL) emission peak of 486 nm. This study demonstrates the effectiveness of DMPO for defect passivation and establishes PAM as a promising interlayer strategy, proving a viable route toward high-performance blue PeLEDs.