A Molecular Precursor-Based Copper Antimony Sulfide Photodetector with Enhanced Performance by Silver Doping

Abstract

Ternary copper chalcogenide semiconductors made of copper antimony sulfide (CuSbS2) are promising absorbers for high-performance photoelectric devices due to their non-toxic, abundant constituent elements and superior optoelectronic characteristics. However, the presence of a large number of CuSb antisite defects and atomic disorder suppress its performance in photodetection. Herein, a non-vacuum, facile spin-coating method based on an organic molecular precursor solution is employed to fabricate the preferable CuSbS2 thin films. With the aid of good adhesion between precursor solution and substrate, compact CuSbS2 thin films are in situ grown on the substrate. Meanwhile, the isoelectronic element of Ag-doped CuSbS2 thin films can be realized by introducing Ag of varying amounts in the precursor. As a result, the concentration of CuSb defects decreases monotonically as the ratio of Ag/(Ag + Cu) increases from 0% to 5%. Compared with the undoped CuSbS2 device, the 5% Ag-doped CuSbS2 photodetector achieves the optimum responsibility (R) of 244.48 A W−1, the external quantum efficiency (EQE) of 749.28% and the specific detectivity (D*) of 8.73 × 1012 Jones, which are increased by 76.4, 76.5, and 38.0 times, respectively. This study provides a novel strategy to achieve high-performance CuSbS2 photodetectors by suppressing the CuSb inversion defects in the Ag-doped thin film.