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 Cu_Sb 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 Cu_Sb 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 Cu_Sb inversion defects in the Ag‐doped thin film.