All inorganic lead-free perovskite Cs2SnI6-based broadband photodetector for optically encrypted data communication

Abstract

Metal halide perovskites have immense potential to revolutionize the semiconducting material horizon. However, most of the prominent perovskite materials face the issue of lead toxicity and air-ambient stability. One of the prominent alternates to Lead (Pb) is Tin (Sn), whereas Sn-based double perovskite (Cs₂SnI₆) is air stable. A one-step process is adopted for the synthesis of Cs₂SnI₆. XRD results confirms the synthesis of Cs₂SnI₆ with significant diffraction peak corresponds to (222) plane. Also, Spin-coated thin film shows same phase of Cs₂SnI₆ as powder material. Stability of the thin film analysed by XRD, which infers that the thin film is for 7 days and after 30 days. Furthermore, the vibrational properties of the Cs₂SnI₆ thin film are characterised by Raman spectroscopy. Raman spectra confirm the Cs₂SnI₆ double perovskite as its A_1g, E_g and F_2g are Sn–I symmetric stretching, Sn–I asymmetric stretching and I–Sn–I asymmetric bending inside the [SnI₆]²⁻ octahedral are observed, respectively. From SEM micrograph, the average grain size of 362 nm with FWHM 268 nm is evaluated for the as deposited thin film. Also, Cs₂SnI₆ thin films are incorporated for Cs₂SnI₆/Si heterojunction diode and its I–V characteristics are analysed. Also, photodetector (PD) is fabricated with Ag/Cs₂SnI₆/Ag device configuration. Photodetection measurements exhibits that fabricated PD device can operate as broadband PD. The characteristic parameters of the fabricated PD are evaluated. Distinguishable current states under the illumination of UV, Vis, and NIR spectra offer the potential applications of PD as data decryption device in optically encrypted data communication.