Engineering the Bandgap and Surface Structure of CsPbCl3 Nanocrystals to Achieve Efficient Ultraviolet Luminescence

Herein, we report the design of novel ultraviolet luminescent CsPbCl3 nanocrystals (NCs) with the emission peak at 381 nm through doping of cadmium ions. Subsequently, a surface passivation strategy with CdCl2 is adopted to improve their photoluminescence quantum yield (PLQY) with the maximum value of 60.5 %, which is 67 times higher than that of the pristine counterparts. The PLQY of the surface passivated NCs remains over 50 % after one week while the pristine NCs show negligible emission. By virtue of density functional theory calculations, we reveal that the higher PLQY and better stability after surface passivation may result from the significant elimination of surface chloride vacancy (VCl) defects. These findings provide fundamental insights into the optical manipulation of metal ion‐doped CsPbCl3 NCs. UV‐emitting halide perovskites are designed by doping Cd2+ into CsPbCl3 nanocrystals to broaden their band gap with the emission peak at 381 nm. Upon treatment with CdCl2, a UV photoluminescence quantum yield up to 60.5 % can be achieved. Transient absorption spectra and first‐principle calculations confirm that the significantly improved optical performance benefits primarily from the marked elimination of surface traps such as a Cl vacancy.