Room‐Temperature Treatment with Thioacetamide Yielding Blue‐ and Green‐Emitting CsPbX3 Perovskite Nanocrystals with Enhanced Photoluminescence Efficiency and Stability

Abstract While multiple protocols are currently available for obtaining green‐ and red‐emitting lead halide perovskite nanocrystals (NCs) with near‐unity photoluminescence quantum yield (PLQY), achieving this target for the blue‐emitting NCs is still quite challenging. This is an impediment to the development of perovskite‐based highly efficient white LEDs of which blue is an essential component. Herein, we show that room‐temperature treatment of the blue‐emitting CsPbCl 1.5 Br 1.5 , cyan‐emitting CsPbClBr 2 and green‐emitting CsPbBr 3 NCs with thioacetamide not only enhances the PLQY to near‐unity (∼97–99%) without affecting the PL maximum and bandwidth, but also improves the stability of the systems significantly. The investigation reveals that effective passivation of under‐coordinated surface Pb 2+ through formation of Pb−S and Pb−NH 2 bonds and removal of excess lead atoms suppress the nonradiative recombination channels and enhances the PLQY and stability of the NCs. Outstanding PL efficiency and superior long‐term stability make these systems potential ingredients for various lighting and display applications.