Organic/inorganic heterointerfaces engineering for balanced charge distribution

Subnanometer-scale lithium fluoride (LiF) layer has been widely employed to enhance electron injection between Al electrode and organic electron transport layers (ETL). However, thermally evaporated ultrathin LiF exhibits incomplete substrate coverage and generates substantial defect-induced charge trapping centers during operation, resulting in poor organic/inorganic interfacial characteristics. In this work, a composite electron injection layer (cEIL) was constructed by combining 8-Quinolinolato lithium (Liq) with excellent interface characteristics of organic/inorganic transition and LiF with strong polarity, which significantly improved the surface potential distribution and achieved balanced charge distribution. The optimized perovskite light-emitting diodes (PeLEDs) demonstrated remarkable electroluminescence (EL) performance enhancement: the external quantum efficiency (EQE) increased from 15.74 % to 20.53 %, and the current efficiency (CE) improved from 73.39 cd/A to 98.59 cd/A. This study provides new insights for organic/inorganic interface engineering in high-performance optoelectronic devices.