Constructing Gradient Energy Levels to Promote Exciton Energy Transfer for Photoluminescence Controllability of All-Inorganic Perovskites and Application in Single-Component WLEDs

Photoluminescence tunability is exceedingly crucial to all-inorganic halide perovskite (CsPbX3 , X = Cl, Br, I) quantum dots (QDs) for high-resolution display. However, up to now, the wide-range color tunability could only be achieved by varying the halide ratio. A drawback in this approach is the color instability caused by inevitable halide ion exchange. Therefore, it is of great significance to exploit the new train of thought to tune the emission color in a wide range. Herein, we designed a novel exciton energy-transfer strategy by introducing the (1)G(4) energy level of Tm to construct the intermediate gradient energy levels between the conduction band of the host perovskite and the T-4(1) energy level of Mn for efficiently promoting the exciton energy transfer from the host perovskite to Mn. Thus, the emission color could be accurately tuned from green to orange, and the corresponding correlated color temperature changed from 12 400 to 1800 K. Most strikingly, the single-component pure white light QDs with a record photoluminescence quantum yield (PLQY) of 54% were obtained based on this strategy. Additionally, white light-emitting diodes with a color rendering index up to 91 and a CIE color coordinate of (0.33, 0.34) are further fabricated. Therefore, we believe that this novel exciton energy-transfer strategy will possibly open up a new avenue for efficient emission controllability of all-inorganic perovskites, promoting the higher PLQY of single-component white light QDs and facilitating practical application.