Graphene/TiO₂ Nanofiber Hybrids for Multispectral Photodetectors

TiO 2 is a wide bandgap material (2.5–3.2 eV); however, defect states within the bandgap of TiO 2 allow certain phototransitions within the visible spectrum. These defect states do not conduct efficiently and increase the exciton recombination rate, leading to poor transport of photogenerated charge carriers, thereby limiting the performance of TiO 2 -based photodetectors. To overcome these limiting factors, graphene was integrated into TiO 2 nanofibers (NFs) using the electrospinning method, and their photoresponse was measured. Transmission electron microscope (TEM) images confirm the presence of 2D ultrathin-layer graphene sheets via liquid-phase exfoliation, alongside TiO 2 /graphene (GeT-NFs) composite nanofibers of diameter 100–300 nm. X-ray diffraction confirms the polycrystalline nature of GeT-NFs, with a crystallite size of 23 nm calculated by using the W–H method. At minimum selected power density, the photodetector fabricated using the GeT-NFs composite exhibits the highest range of responsivity, ranging from 12 mA/W to 0.5 mA/W, and detectivity ranging from 1.92 × 10 9 to 3.48 × 10 7 Jones from UV to IR region (380–1000 nm). The GeT-NFs composite has fast rise and fall times, ranging from 0.5/1.5 s to 1/1.5 s, respectively, at different wavelengths.