LAUSR

We demonstrate that Ag(I) complex can fix bromide on the nanocrystal surface, reduce surface trap density, and as a result efficiently passivate the surface of CsPbBr3 nanocrystals. This passivation makes the photoluminescence (PL) intensity increase several times. The PL kinetics study clearly shows that the decay lifetime increased after the passivation. TEM and XPS analyses demonstrated the existence of Ag on the nanocrystal surface. In addition, we utilize single-particle spectroscopy combined with in situ light analysis to further confirm the PL enhancement effect. On the contrary, the passivation leads to the extraordinary photostability of CsPbBr3 nanocrystals, with 80% PL intensity retained after UV illumination for 5 days under ambient conditions.