Bi3+ and Eu3+ co-doped CsPbCl3 perovskite quantum dots with efficient controllable blue emission via energy transfer

Halide perovskite quantum dots (QDs) are considered to be an outstanding optoelectronic and photonic materials. However, the heavy usage of toxic Pb element is still a serious problem, which can greatly hinder their practical application. Herein, co-doping of different metal ions pairs in perovskite QDs host can solve this problem without affecting their optical properties. The highly monodisperse low-Pb content Cs(Pb1-xBix)Cl3 (x = 0.02–0.1) and Cs(Pb0.95-yBi0.05Euy)Cl3 (y = 0.05–0.50) perovskite QDs with cubic morphologies are successfully obtained by using the improved hot-injection method in the present work. The metal ions (Bi3+ and Eu3+)-doped do not alter the crystal structure, maintaining the tetragonal crystalline structure of the CsPbCl3 host, but has an effect on the particle size owing to the difference in the ionic radius. Under the UV excitation wavelength of 380 nm, the perovskite QDs after doping with metal ions all display their respective typical emission bands, including the band-edge emission of CsPbCl3 host, the 3P1 → 1S0 transition of Bi3+, and the 5D0 → 7F2 transition of Eu3+. The relative intensities and the positions of their typical emission bands can be tuned by changing the Bi3+ or Eu3+ content, indicating the emission color of samples can be controlled. The interesting spectroscopic behaviour benefits from the efficient energy transfers between the CsPbCl3 host and doped metal ions, and the energy transfers are owing to the differences in intrinsic energy levels of Bi3+ or Eu3+. The metal ions-doped CsPbCl3 perovskite QDs developed in this work can reduce the toxicity of perovskite QDs while improving the optical performance, which can provide a novel platform for the application in optoelectronic device applications.