Efficiency Enhancement Strategies for Stable Bismuth-Based Perovskite and Its Bioimaging Applications

Lead-free perovskite is one of the ideal solutions for the toxicity and instability of lead halide perovskite quantum dots. As the most ideal lead-free perovskite at present, bismuth-based perovskite quantum dots still have the problem of a low photoluminescence quantum yield, and its biocompatibility also needs to be explored. In this paper, Ce³⁺ ions were successfully introduced into the Cs₃Bi₂Cl₉ lattice using a modified antisolvent method. The photoluminescence quantum yield of Cs₃Bi₂Cl₉:Ce is up to 22.12%, which is 71% higher than that of undoped Cs₃Bi₂Cl₉. The two quantum dots show high water-soluble stability and good biocompatibility. Under the excitation of a 750 nm femtosecond laser, high-intensity up-conversion fluorescence images of human liver hepatocellular carcinoma cells cultured with the quantum dots were obtained, and the fluorescence of the two quantum dots was observed in the image of the nucleus. The fluorescence intensity of cells cultured with Cs₃Bi₂Cl₉:Ce was 3.20 times of that of the control group and 4.54 times of the control group for the fluorescence intensity of the nucleus, respectively. This paper provides a new strategy to develop the biocompatibility and water stability of perovskite and expands the application of perovskite in the field.