Simple and solvent-free procedure for fabricating Ag/Bi-based halide double perovskite polycrystalline wafers and investigating their photodetector properties

Abstract

Herein, a solvent-free and simple solid-state method was used to synthesize Cs2AgBiBr6 wafers. Cs2AgBiBr6 particles were successfully synthesized in two steps, namely grinding and annealing. Phase-pure Cs2AgBiBr6 was produced in a very short time, such as 4 h, by stepwise heat treatment at 205 °C for 2 h and 250 °C for 2 h after grinding bromide powders for 20 min in an agate mortar. Another grinding step for 20 min, following the phase-pure synthesis of Cs2AgBiBr6, facilitated the formation of larger perovskite grains through sintering at 350 °C. Increasing the sintering time from 4 h to 20 h also contributed to the formation of larger and more compact perovskite grains. This study demonstrated that the formation of larger and more compact grains through sintering at 350 °C for 20 h contributes to better detectivity and responsivity values for solvent-free produced Cs2AgBiBr6 wafers. Additionally, the structural strength of the material was examined through hardness tests using the nanoindentation method, resulting in a value of 0.0923 MPa. The simple and solvent-free method employed in this study may create opportunities to fabricate emerging double perovskites for detector applications.