High-efficiency perovskite light-emitting diodes enabled by introducing a LiF modification layer

Surface defect passivation and exciton regulation remain a critical challenge in perovskite light-emitting diodes (PeLEDs). Organic molecules are widely used to solve these issues. However, the high sensitivity of perovskite films to the molecular groups and concentration limited their commercialization applications. Here, we develop a facile and low-cost passivation strategy that is compatible with traditional fabrication processes of PeLEDs. By depositing a thin LiF layer using vacuum thermal evaporation technique, the defects of perovskite film are effectively passivated. Simultaneously, the thin LiF layer protects the excitons formed in perovskite from quenching by the electron-transport layer. Due to the synergistic effect of LiF, an efficient green PeLED is achieved with a maximum current efficiency of 47.0 cd/A and luminance of 30 280 cd/m2, representing respective 65% and 166% increase than that of the control device without LiF modification layer (28.5 cd/A and 11 380 cd/m2). Our work provides an effective strategy and deep understanding of the interface regulation for achieving high-performance PeLEDs.