Mixing Entropy-Induced Layering Polydispersity Enabling Efficient and Stable Perovskite Nanocrystal Light-Emitting Diodes

Colloidal perovskite nanocrystals are emerging as one of the most promising candidates for next-generation monochromatic light sources that require precise bandgap tunability. However, the current efficiency (η_CE) and operational lifetime in their light-emitting diodes (LEDs) remain low due to impeded carrier transport and exciton quenching through the NC ligand layer. Here, we show that the fundamental limitation can be overcome in the superstructures containing polydisperse colloidal quantum wells of organic–inorganic hybrid perovskites. The mixing entropy-induced layering polydispersity promotes the delayed radiative energy transfer (DRET) that guides exciton transport with negligible nonradiative losses, boosting the thin-film photoluminescence quantum yield >96%. By using the superstructures in LEDs, we report a η_CE of 30.4 cd A^–1, with an operational lifetime (LT₅₀) of 184 min at a high constant driving current of 10 mA cm^–2. These are among the most high-performance colloidal perovskite nanocrystals LEDs ever demonstrated.