Improvement in Response Speed of a AgSbS2 Photodetector by Alloy Engineering

The ternary metal chalcogenide AgSbS2 has been regarded as a promising photovoltaic compound due to its excellent stability and nontoxicity. However, the response time of the as-prepared AgSbS2 photodetectors is longer by several orders of magnitude than the time required for practical application, appealing to an improving strategy by alloy engineering. Herein, we fabricated AgSb1–x Bi x S2 (x = 0–0.5) photodetectors and investigated their photoresponse behaviors. In comparison with the AgSbS2 photodetector, the as-prepared AgSb0.7Bi0.3S2 photodetector demonstrates a remarkable reduction in response time by more than 3 orders of magnitude. It is found that the trap level of AgSb0.7Bi0.3S2 is ∼0.2 eV shallower than that of AgSbS2, which contributes to the dramatic decrease in response time. This work demonstrates that alloy engineering provides an effective solution to considerably shorten photodetector response time and essentially facilitates device optimization.