Eu3+, Tb3+ doping induced tunable luminescence of Cs2AgInCl6 double perovskite nanocrystals and its mechanism

Incorporation of lanthanide ions (Ln 3+ ) can remarkably enhance the structural stability and optical properties of lead-free perovskite NCs. Herein, we have established the relationship between the intrinsic emission of Cs 2 AgInCl 6 host and the Ln 3+ by Eu 3+ , Tb 3+ doping in Cs 2 AgInCl 6 NCs, realizing tunable luminescence of NCs in the visible region. Experimental studies and density functional theory (DFT) calculations analysis show that Eu 3+ and Tb 3+ occupy the sites of In 3+ in Cs 2 AgInCl 6 , the defect formation energy for Cs 2 AgInCl 6 :Ln 3+ is larger than the pristine Cs 2 AgInCl 6 , resulting in a more stable cubic double perovskite structure. The optical band gap increases with the increase in Ln 3+ doping percentage. Turning excitation from 250 nm to 300 nm, the broad self-trapped excitons (STEs) emission is more remarkable, and the narrow Ln 3+ emission is less notable. The emitted color can be adjusted from white to red and to green light by altering the doping concentration of Eu 3+ or Tb 3+ and excitation wavelength. This work promotes the design and optoelectronic application of desired lead-free perovskites.