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. This article presents a holistic processing strategy to fabricate perovskite films by vapor‐phase deposition (VPD). Post‐deposition CsBr enrichment treatment is used to obtain stable embedded perovskite nanocrystals with near‐unity photoluminescence quantum yields. The VPD fabricated light‐emitting diodes yield bright luminance ≈15 000 cd m−2 at 523 nm with a narrow 18 nm peak width.