Charge transport properties and variable photo-switching of three-terminal Cs2AgBiBr6 device

Abstract In this study, we present an in-depth exploration of charge transport phenomena and variable photo-switching characteristics in a novel double-perovskite-based three-terminal device. The Cs 2 AgBiBr 6 thin film (TF) was synthesized through a three-step thermal evaporation process followed by precise open-air annealing, ensuring superior film quality as confirmed by structural and morphological characterizations. Photoluminescence spectroscopy revealed distinct emissions at 2.28 and 2.07 eV, indicative of both direct and indirect electronic transitions. Our device exhibited space-charge limited current (SCLC) behaviour beyond 0.35 V, aligning with the relationship , where the exponent m transitioned from ≤1 to >1. Detailed analysis of Schottky parameters within the trap-filled limit (TFL) regime was conducted, accounting for variations in temperature and optical power. Significantly, the self-powered photodetector demonstrated outstanding performance under illumination. The sensitivity of the device was finely tunable via the applied bias voltages at the third terminal. Notably, an optimal bias voltage of ±100 μ V yielded maximum responsivity ( R ) of 0.48 A/W and an impressive detectivity ( D* ) of 1.07 × 10 9 Jones, highlighting the potential of this double-perovskite-based device for advanced optoelectronic applications.