Highly Luminescent CsPbBr@CsPbBr Nanocrystals and Their Application in Electroluminescent Emitters.

Zero-dimensional perovskite nanocrystals (NCs) are becoming the most attractive material due to their excellent optical performance and better stability compared with high-dimensional perovskite. However, their application in electroluminescent (EL) emitters for high-quality displays is still limited. In this work, we successfully achieved CsPbBr@CsPbBr NCs around 13.9 ± 0.2 nm by using the hot-injection method. Additional SnBr was mixed in the PbBr precursor to provide extra Br ions and reduce the excessive amount of Pb ions to promote the formation of CsPbBr@CsPbBr. Time resolution photoluminescence analysis indicated that the green emission of our CsPbBr@CsPbBr NCs originated from the embedded CsPbBr NCs, which corresponds to our previous research. The CsPbBr crystals passivated the surface of CsPbBr NCs, resulting in the absence of trions for the high photoluminescence quantum yield. The as-synthesized CsPbBr@CsPbBr NCs were used to fabricate quantum dot light-emitting diode (QLED) devices with the highest current efficiency of 4.89 cd/A. This is the best performance of the CsPbBr@CsPbBr-system QLED device, which reveals the great potential of CsPbBr@CsPbBr NCs and will inspire further study of zero-dimensional perovskite composite NCs for EL emitters.