Crystallization control via a molecular needle knitting strategy for the enhanced emission efficiency and stability of CsPbBr3 films

Abstract

Controllable crystallization growth of perovskite films with excellent morphology and outstanding properties is a key and intractable problem for efficient and stable perovskite optoelectronic devices. However, the inhomogeneous inherent defects at the grain boundaries and interfaces make it difficult to uniformly release the residual stress during the growth process of perovskite films. Here, a molecular needle knitting strategy with dimethyl sulfoxide solvent as needles and polyoxyethylene molecular chains as threads was proposed to reveal the growth mechanism of perovskite–polymer composite films. Owing to the knitted net-structured cages synergistically constructed by the molecular needles and threads, the perovskite precursors can be uniformly assigned to each cage and nucleated evenly for the effective residual stress release under the formed spatial confinement effect. Compared with no confined cages, this obtained CsPbBr₃ film via the molecular needle knitting strategy showed 50% enhanced photoluminescence quantum yield together with 40% improved stabilities. Based on this CsPbBr₃ film and an UV LED chip (365 nm), we fabricated a high-stability and pure green LED lamp (528 nm). This work may open a way to achieve high quality fluorescent perovskite films and further extend their practical application in lighting and display fields.