Vapor-Phase Deposition of Highly Luminescent Embedded Perovskite Nanocrystals

Vapor-phase deposition (VPD), a process that can be readily scaled up for mass production, provides a cost-effective approach to manufacture perovskite light-emitting diodes (LEDs). The progress in device efficiency, however, has been stagnant, owing largely to the poor photoluminescence quantum yields (PLQYs) of the VPD materials. Herein, a holistic fabrication strategy is reported that can stabilize the otherwise thermodynamically unstable cubic-phase through the deposition of a CsBr-rich termination on top of the CsPbBr₃ films. The enhanced film reduces the electronic defects considerably resulting in near-unity PLQY of the VPD-based perovskites. To understand the mechanism of the improved VPD-CsPbBr₃ perovskite, advanced optical probing techniques and structural characterizations are used. For device application, the LEDs made from the VPD perovskites yield a bright luminance of ≈15 000 cd m⁻² at 523 nm with a sharp full width at half maximum (FWHM) of 18 nm.