Enhancement of the efficiency and thermal stability of the double perovskite Cs2AgInCl6 single crystal by Sc substitution

Cs2AgInCl6 lead-free double perovskite materials have potential applications in lighting and high-energy ray detection. However, the transition of Cs2AgInCl6 single crystals (SCs) is parity forbidden, resulting in low photoluminescence (PL) efficiency. In this study, we provide a strategy to break the parity forbidden transition by substituting Sc for In. The PL efficiency is greatly increased by 43%. In addition, the thermal stability is improved from 7.4%@475 K to 51.3%@475 K, which is attributed to the formation of Sc–Cl covalent bonds instead of In–Cl ionic ones. These results demonstrate that a suitable method makes a great contribution to promoting the possible application of Cs2AgInCl6 in the future.