Excitonic Luminescence Engineering in Tervalent-Europium-Doped Cesium Lead Halide Perovskite Nanocrystals and Their Temperature-Dependent Energy Transfer Emission Properties

Cesium lead halide (CsPbX3 (X = Cl, Br, I)) perovskite nanocrystals (NCs) have shown excellent prospects in lighting, display, and lasing fields owing to their excellent photoluminescence (PL) properties. To dope rare earth ions into halide perovskite, CsPbX3 (X = Cl, Br, I) NC hosts not only inherit the excellent narrow linewidth excitonic properties but also yield unique photoluminescence emission. Herein, engineering of such excitonic luminescence is achieved for Eu3+-doped CsPbCl3-xBrx (x = 0, 1, 1.5, 2, 3) solid solution NCs for the first time. The singly doped NCs present wide color gamut emission covering the whole visible spectrum. The blue to-green range (400-520 nm) emission is covered by tunable excitonic photoluminescence of CsPbX3 NCs. Besides, there is a broad red spectral region (590-700 nm) originating from the emission of the tervalent europium ions in NCs. Meanwhile, a noticeable spin-polarized D-5(0) -> F-7(1-6) emission of Eu3+ ions is obtained owing to energy transfer from excitons to dopants. Moreover, the energy transfer is temperature-dependent, which originates from the increase of nonradiative transition probability, leading to the decrease of the PL intensity of NC hosts and the increase of the PL intensity of dopants.