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

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.