Simple synthesis of Bi3+ and Fe3+ co-doped Cs2Ag0.6Na0.4InCl6 double perovskite and its dual emission mechanism

The lead-free double perovskite with low toxicity and good performance stability has attracted much attention in optoelectronic device applications. But their photoluminescence quantum yields (PLQY) are low, which limits their applications. Co-doping and alloying are the most valuable methods to improve its PLQY and stability. In this study, we successfully synthesized Bi3+ and Fe3+ co-doped Cs2Ag0.6Na0.4InCl6 double perovskite using the hydrothermal method, and the emission mechanism was further investigated. Under UV-light excitation, the Cs2Ag0.6Na0.4InCl6: Bi3+/Fe3+ shows dual emission. This emission results from the modification effect of self-trapped exciton (STE) formation, and Fe3+ induces longer wavelength emission. By changing the doping contents of Bi3+ and Fe3+, the revolution of double perovskite color from yellow to orange-red can be observed, and its PLQY is up to 39.95%. The studies of the PL emission mechanism reveal that energy transfer occurs between the STE and Fe3+, and different doping contents can affect this transfer mechanism. This work has implications for producing double perovskite for optoelectronic semiconductors and provides direction for designing new lead-free double perovskites.