Charge carrier recombination and ion migration in metal-halide perovskite nanoparticle films for efficient light-emitting diodes

Metal-halide perovskite (MHP) nanoparticles (NPs) have attracted considerable attention as a promising light emitter for efficient light-emitting diodes (LEDs) due to their high color-purity and photoluminescence quantum efficiency (PLQE). In contrast to MHP polycrystalline (PC) bulk films, charge carrier recombination as well as ion migration dynamics in MHP NP films have not been studied yet despite the importance to achieve high electroluminescence efficiency in LEDs. Here, we use steady-state and transient photoluminescence measurements, and photo-responsivity analysis to study the charge carrier recombination and ion migration dynamics in MHP NP films and then, compare these with those of MHP PC films. Results show that MHP NP films do not undergo the severe ion migration and have dominant radiative recombination of excitons by efficiently confining electron-hole pairs. As a result, MHP NP films have high photo-stability, photo-responsibility, and PLQE (> 60%). Our findings provide insight into charge carrier and ion dynamics in MHP NP films, and confirm the potential of NP films for use in efficient LEDs.