Synthesis of All-Inorganic Cd-Doped CsPbCl₃ Perovskite Nanocrystals with Dual-Wavelength Emission

Doped lead halide perovskite nanocrystals (NCs) have garnered significant attention due to their superior optoelectronic properties. Here, we report a synthesis of Cd-doped CsPbCl₃ NCs by decoupling Pb- and Cl-precursors in a hot injection method. The resulting Cd-doped perovskite NCs manifest a dual-wavelength emission profile with the first reported example of Cd-dopant emission. By controlling Cd-dopant concentration, the emission profile can be tuned with a dopant emission quantum yield of up to 8%. A new secondary emission (∼610 nm) is induced by an energy transfer process from photoexcited hosts to Cd-dopants and a subsequent electronic transition from the excited state (³E_g) to the ground state (¹A_1g) of [CdCl₆]^4- units. This electronic transition matches well with a first-principles density functional theory calculation. Further, the optical behavior of Cd-doped CsPbCl₃ NCs can be altered through postsynthetic anion-exchange reactions. Our studies present a new model system for doping chemistry studies in semiconductors for various optoelectronic applications.