Yb and Yb/Er Doping for Near-Infrared Emission and Improved Stability of CsPbCl Nanocrystals.

Lead halide perovskite nanocrystals (NCs) exhibit excellent tunable emissions covering the entire visible spectral region, but they do not emit near-infrared (NIR) light. We synthesized rare earth element doped CsPbCl NCs for NIR emission. The Yb doped CsPbCl NCs emitted strong 986 nm NIR light; the Yb/Er co-doped CsPbCl NCs emitted at 1533 nm. The total photoluminescence quantum yield (PL QY) of the CsPbCl NCs changed from 5.0% to 127.8% upon incorporating 2.0% Yb, a factor of 25.6 times enhancement. The material's stability was tested under continuous ultraviolet (365 nm) irradiation. The doped CsPbCl NCs exhibited a better stability than the undoped one. The PL intensity of the undoped CsPbCl NCs dropped to 20% of the initial value in 27 h, while the doped one took 85 h.