Aqueous strategy for controllable in-situ growth of high-quality perovskite nanocrystals@polymer films toward white light-emitting diodes

Perovskite nanocrystals (PNCs)@polymer films are one of the exciting candidates for fabricating high-definition display devices, owing to their universal merits such as high efficiency, superior color purity, and tunable emissions. However, the existed techniques are always based on organic solvents, of which the inevitable toxicity greatly limits their scalable applications. Herein, we report a facile strategy based on a distinctively different aqueous route for in-situ growth of MAPbBr3 (MA = CH3NH3+) PNCs in polyvinyl alcohol (PVA) matrix, enabling the environmentally-friendly and large-scale production of high-photoluminescence (PL) PNCs@polymer films. It is discovered that rapid evaporation of solvents in the precursor film is the key to separated crystallization of polymer and PNCs, thus allowing the controllable fabrication of high-quality PNCs@PVA films with tunable emissions. As a proof of concept, the as-fabricated MAPbBr3 PNCs@PVA film with typical size of 90 mm x 90 mm exhibits high transmissivity and uniformity, with a strong green emission and PL quantum yield (QY) of 95.3%. Accordingly, by using the resultant green and red films, a white light-emitting device (WLED) sized 35 mm x 40 mm is assembled, which delivers a wide color gamut (121% of NTSC standard), underscoring their very promising applications in modern display devices.