Fabrication of Bi19S27I3 nanorod cluster films for enhanced photodetection performance

Thin-film photodetectors built from one-dimensional nanostructures have attracted extensive attention due to their significance in basic scientific research and potential technological applications. It is still desirable to develop new materials with a wide response range for application in photodetectors. In this work, a Bi19S27I3 nanorod cluster film has been successfully fabricated on various rigid substrates by a facile solvothermal method. The component nanorods exhibit an oriented growth along the [001] direction. The UV-Vis-NIR absorption spectrum shows a continuous strong absorption spanning the whole visible light to near-infrared region and presents a direct band gap of 0.83 eV for the prepared Bi19S27I3 nanorod clusters. The spectral photoresponse of the Bi19S27I3-based photodetector device demonstrates a broad photoresponse ranging from ultraviolet to near infrared. The photocurrent results reveal that the photodetector exhibits a more sensitive response towards near-infrared light than visible light. Furthermore, the photodetector based on the Bi19S27I3 nanorod cluster film shows significantly enhanced photodetection performance compared to Bi19S27I3 nanorod powder. The photocurrent and on–off ratio of the prepared nanorod cluster film are respectively up to 400 times and several times higher than those of the powder sample. The on–off ratios are about 265 and 66 under NIR illumination and 48 and 11 under visible light for the film and powder samples, respectively. These results suggest a great potential application of the prepared Bi19S27I3 nanorod cluster film in optoelectronic devices.