Achieving Near-Unity Photoluminescence Efficiency for Blue-Violet-Emitting Perovskite Nanocrystals

While perovskite nanocrystals (NCs) have shown great promise as materials for efficient light-emitting diodes (LEDs), low photoluminescence quantum yield (PLQY) of the blue-emitting perovskites is an impediment to the development of white LEDs of which blue is an essential component. Herein, we report that room temperature postsynthetic treatment of weakly blue-violet-emitting (PLQY 3%) CsPbCl3 NCs with CdCl2 results in an instantaneous enhancement of the PLQY to near-unity without affecting the PL peak position (406 nm) and spectral width. The time-resolved PL and ultrafast transient absorption measurements confirm the removal of nonradiative defect states of the CsPbCl3 NCs in treated sample. The elemental composition and structural data of the treated sample reveal facile doping of Cd2+ into the crystal lattice without affecting the size and shape of the NCs. Extraordinary PLQY, high air stability and photostability and ease of preparation of this Cd-doped CsPbCl3 make it by far the most attractive blue-emitting perovskite for development of efficient blue and white LEDs.