Yb²⁺-Alloyed Cs₄PbI₆-CsPbI₃ Perovskite Nanocomposites for Efficient and Stable Pure-Red Emission

A series of Yb²⁺-alloyed CsPb_1-YbI₃ (x = 0, 0.2, 0.4, 0.6) perovskite nanocrystals (NCs): are synthesized by a modified hot-injection method. Yb²⁺ alloying induced a blue shift of photoluminescence (PL) spectra. In particular, when x = 0.6, the perovskite NCs exhibit pure-red emission with PL centered at 638 nm. Furthermore, the perovskite NCs with pure-red emission exhibit enhanced air and thermal stability, compared to pure CsPbI₃ NCs. The enhanced stability can be assigned to the formation Cs₄PbI₆-CsPbI₃:Yb composites. Charge-carrier dynamics study indicates that the Cs₄PbI₆-CsPbI₃:Yb composites exhibit ultrafast hot-carrier cooling processes, which could break the Auger reheating effect. These properties suggest the Yb²⁺ alloyed CsPbI₃ perovskite NCs have great potential for high-performance pure-red light-emitting diodes.