Temperature-dependent photoluminescence of Cs2AgxNa1-xInCl6 microcrystals

Cs2AgxNa1-xInCl6 microcrystals (MCs) are synthesized using a solvothermal method. The regular variation of Na incorporation is characterized according to the intensity change of the X-ray diffraction and ultraviolet visible absorption peaks. Temperature-dependent photoluminescence (PL) properties of Cs2AgxNa1-xInCl6 MCs are studied by use of steady-state PL and time-resolved PL (TRPL) measurements. From steady-state PL, it is verified that the white-light emission primarily originates from self-trapped excitons (STEs) at low temperature (80–290 K). When the electron-phonon interactions become stronger, STEs are promoted to generate from free excitons (FEs). And the high temperature-dependent (293–450 K) PL reveals the thermal quenching process. Temperature-dependent TRPL demonstrates that the change of lifetimes is attributed to band-edge FEs state and STEs state. It is found that the electrically-driven PL decreases to 70% then becomes stable from 0 to 120 min when light-emitting diodes (LEDs) are fabricated to explore the thermal stability. Our results suggest these white-emission Cs2AgxNa1-xInCl6 MCs can be used as excellent materials for LEDs and provide reference to engineer such MCs toward practical optoelectronic applications.