Scalable colloidal synthesis of uniform Bi2S3 nanorods as sensitive materials for visible-light photodetectors

Abstract

A facile colloidal chemistry method is reported for synthesis of uniform Bi₂S₃ nanorods in a mixed solution of oleylamine with other organic amines including n-dodecylamine (C₁₂), n-octylamine (C₈), and n-hexylamine (C₆). The nanorod length can be tuned through the carbon-chain length of these amines and importantly multigrams of Bi₂S₃ nanorods can be readily synthesized in a single scaled-up batch. Current–voltage (I–V) measurements showed that the Bi₂S₃ nanorods, obtained from both the small and large-scale batches or ones with different chain-length amines, exhibit fast light response characteristics (at the sub-second scale) with an obviously enhanced photocurrent (or photoconductivity) under broad-spectrum white light or monochromatic visible light of different wavelengths. The as-obtained nanorods, as determined by time-dependent current (I–t) curves, also exhibit excellent photoresponsive stability and reproducibility with the on–off switch of light. The photoconductivity enhancement in the Bi₂S₃ nanorods is assigned to the efficient electron–hole pair separation due to a hole-trapping mechanism. These results indicate the promising potential of Bi₂S₃ nanorods for optoelectronic device applications including photodetection (sensing), optical switch, photocatalysis, and photovoltaics within the visible spectrum range.