Triflate-Passivated Perovskite Colloidal Nanocrystals with Enhanced Emission Performance for Wide-Color-Gamut Backlight Display

Insufficient photoluminescence quantum yields (PLQYs) and instability issues are the main obstacles to the practical application of lead halide perovskite colloidal nanocrystals (NCs). Herein, we present a room temperature strategy using a triflate salt [e.g., cerium(III) triflate; Ce(OTf)3, where OTf = −SO3CF3] treatment for surface defect engineering of NCs, providing the treated NCs with a huge boost in the photoluminescence (PL) intensity. The PLQY value of green NCs increases from 55.3 to 84.4%, and a tremendous increase from 1.9 to 35.5% is achieved for blue NCs. The time-resolved spectroscopic studies and theoretical calculations based on density functional theory suggested that the defect states related to the surface Br vacancies and uncoordinated Pb atoms were efficiently passivated by the [OTf]− groups with a larger adsorption energy (Eads), resulting in the prolonged PL lifetime and enhanced PL emission for the treated colloidal NCs. The treated NCs are also apparently superior to the pristine NCs in terms of thermal stability. Furthermore, the white-light-emitting diode fabricated with the treated NCs exhibited a broad color gamut (131.4% of the National Television System Committee), which demonstrated the potential for their practical application in the field of backlight-display technology.