Engineering Space-Confined Perovskite Nanocrystal Films for Rec. 2020-Compliant Pure-Green Light-Emitting Diodes with Enhanced Operational Stability

Perovskite light-emitting diodes (PeLEDs) hold great promise for next-generation displays, yet their operational stability remains a key challenge. Here, we report stable, bright, efficient, and Rec. 2020-compliant pure-green PeLEDs by rationally engineering nanocrystalline perovskites that exceed the Bohr exciton diameter while preserving high crystalline quality. The beneficial size effects such as space confinement and nonlocal interaction promote sufficient charge recombination and suppress Auger recombination. Moreover, the high-quality nanocrystals with an anchored surface exhibit reduced crystal defects and mitigated ion migration under bias. These combined features substantially improve device stability. Such high-quality perovskites are achieved via deliberate in situ synthesis incorporating the partial substitution of formamidinium tetrafluoroborate for bromide precursors in an established co-additive system. The resultant PeLEDs, compliant with Rec. 2020 standards, exhibit an estimated half-lifetime of 33,000 h at 100 cd m −2, luminance of 310,000 cd m −2, and maximum external quantum efficiency of 26.61%, representing one of the best-performing pure-green nanocrystalline PeLEDs to date.