Metal Work Function Effects on the Performance of UV–Visible–NIR Cs₂SnI₆ Photodetectors for Flexible Broadband Application

Abstract

Herein, the role of top metal electrode work functions on the performance of flexible broadband ultraviolet (UV)–visible–near‐infrared (NIR) flexible Cs2SnI6 (CSI) photodetectors (PDs) are reported in the present study. The change in crystal plane orientation, surface morphology, and chemical composition of prepared films compared to hydrothermally synthesized CSI particles is confirmed by physical characteristics tools. The optical bandgap of CSI films is estimated to be 1.36 eV. The flexible CSI PDs are fabricated with three top metal electrodes (Mo, Ti, and Ni). The current–voltage (I–V) characteristics under the illumination of light sources with different wavelengths reveal the broadband UV–visible–NIR photodetection properties of flexible CSI PDs. The device with top Ti electrodes demonstrates maximum photoresponsivity (Rph = 1.65 ± 0.45 A W−1) and specific detectivity (Dph = 4.53 ± 0.36) × 1010 Jones for 455 nm compared to other wavelengths at Vb = 5 V. The fast photoresponse/decay time is 18 ms/24 ms for 455 nm at Vb = 1 V. The 85% and 90%–95% retentions of Rph of devices after 12 days keeping in a desiccator and after 500 bending cycle tests suggest the device's good environmental stability and mechanical flexibility, respectively. Thus, it is indicated in the results that CSI materials can be a potential candidate for flexible UV–visible–NIR photodetector for wearable electronic device applications.