Novel Composite of Nickel Thiocyanate‐Based All‐Inorganic Lead Bromide Perovskite Nanocrystals with Enhanced Luminescent and Stability for White Light‐Emitting Diodes

Abstract Doping of CsPbBr₃ perovskite nanocrystals (PNCs) to achieve excellent material properties is accelerating due to their increasing use in optoelectronic devices. Herein, a novel composite of CsPbBr₃ PNCs with nickel thiocyanate Ni(SCN)₂ is reported, exhibiting stronger photoluminescence (PL) and more extended stability. The addition of Ni(SCN)₂ at different molar concentrations reduces the surface trap states of the host PNCs. Therefore, the microstrain, dislocation density, PL emission linewidth, and Urbach energy decrease, resulting in an increased photoluminescence quantum yield (PLQY) from 72% to high above 90%. When stored in the ambient atmosphere for 120 days, the PLQY of doped PNCs is maintained by more than four times compared to host PNCs. A combination of 3D‐printed conversion layers containing green‐, yellow‐, and red‐emitting doped PNCs with blue light‐emitting diodes results in stable white light with superior color qualities. Hence, new composites with desired properties are developed as an alternative to conventional color phosphors.