Formadinium Cation Doping Stabilized Ultra-deep-blue Lead Halide Perovskite Nanocrystal Light-emitting Diodes

The halide migration effect in mixed-halide lead-based perovskite is a serious problem hindering the development of its display technology. In this study, we have successfully addressed this issue by reporting formadinium (FA) doped mixed-halide perovskite nanocrystals (NCs) with ultra-deep-blue emission of 450 nm, narrow bandwidth of 16 nm, and a high photoluminescence quantum yield (PLQY) of 66%. The perovskite nanocrystal light-emitting diodes (NC-LEDs) using this nanocrystal as an active layer achieved a maximum external quantum efficiency (EQE) of 0.32%, 30-fold improved compared to that of pristine and stable electroluminescence (EL) spectra at 450 nm under a 4.9–8.0 V bias. These findings demonstrate the potential of our approach in developing stable and efficient deep blue perovskite NC-LEDs.