Enhanced Cyan Photoluminescence and Stability of CsPbBr3 Quantum Dots Via Surface Engineering for White Light‐Emitting Diodes

Abstract The emission of cyan light (470‐500 nm) plays a vital role in the visible light spectrum and is essential for applications such as lighting, displays, and optical communication. Inorganic cesium lead bromide perovskite quantum dots (CsPbBr 3 PQDs) have made significant progress in the field of luminescence materials and devices, however, the lack of techniques to obtain highly emissive and stable cyan‐emitting CsPbBr 3 PQDs has limited their device applications. Here, it is demonstrated that the complete surface passivation by treatment of didodecyldimethylammonium bromide (DDAB) and lead bromide, which can enhance the photoluminescence and stability of cyan emitting CsPbBr 3 PQDs. In particular, the photoluminescence quantum yield of CsPbBr 3 QDs can be greatly improved from 10.5% to 83.8%. Through an effective PMMA passivation, the obtained stable and bright CsPbBr 3 PQDs composite films as the cyan color converters can effectively emit the cyan light to fill the “cyan gap” of white light‐emitting diode (WLED). The color rendering index value of such WLED is remarkably enhanced from 73.6 to 82.5. This study paves the way for the application of PQD color converters in the next generation of full‐visible‐spectrum WLED lighting.