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 (V_Cl ) defects. These findings provide fundamental insights into the optical manipulation of metal ion-doped CsPbCl₃ NCs.