High-Performance Visible Light Photodetector Based on 1D SnO₂ Nanofibers with a Ti₃C₂T<i>_x</i> (MXene) Electron Transport Layer

Abstract

One-dimensional (1D) nanostructures have received widespread attention in optoelectronics due to their fascinating physical and chemical properties that arise from quantum effects at the nanoscale. Furthermore, there is scope to explore metal oxide-based 1D nanostructures and their composites for developing high-performance optoelectronic devices. This report is the first demonstration of a SnO2/MXene 1D nanofiber composite-based visible light photodetector on a rigid p-type Si substrate. The SnO2 + MXene/Si(p) photodetector was fabricated using a simple and economical electrospinning technique. The responsivity (R) of the as-fabricated Si(p)/SnO2 + MXene photodetector displayed an enhanced value, i.e., ∼64 AW–1, in comparison to that of the Si(p)/pristine SnO2 photodetector (∼12 AW–1) under a visible light illumination of 0.25 mW cm–2 and 554 nm wavelength, which suggests that MXene as a transport layer vastly enhances the performance of the device. In addition, the 1D nanofiber composite photodetector exhibited high-speed switching characteristics with a response and recovery time of ∼123 and ∼60 ms, respectively. The excellent performance of the as-fabricated photodetector can be attributed to three reasons mainly: (1) The MXene acts as an electron acceptor, and charge transfer occurs across the SnO2/MXene Schottky heterojunction, with photogenerated electrons rapidly migrating to the MXene surface, where they get transported and collected quickly (owing to the high mobility of charge carriers in MXene) at the electrodes. (2) A high density of deep-level surface states is present at the SnO2/MXene interface where minority carriers (holes) get trapped and are unavailable for recombination, thereby increasing the concentration of majority carriers (electrons). (3) A built-in electric field at the main heterojunction between the p-type Si and the 1D nanofiber composite assists the charge separation of photogenerated carriers under an applied reverse bias. The successful fabrication of such high-performance photodetectors is a significant step in developing next-generation optoelectronic devices based on novel composite nanomaterials with immense potential in diverse applications across science and engineering domains.