Carrier recombination suppression and transport enhancement enable high‐performance self‐powered broadband Sb₂Se₃ photodetectors

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Antimony selenide (Sb 2 Se 3 ) is a promising candidate for photodetector applications boasting unique material benefits and remarkable optoelectronic properties. Achieving high‐performance self‐powered Sb 2 Se 3 photodetector through a synergistic regulation of absorber layer and heterojunction interface demonstrates great potential and needs essential investigation. In this study, an effective two‐step thermodynamic/kinetic deposition technique containing sputtered and selenized Sb precursor is implemented to induce self‐assembled growth of Sb 2 Se 3 light absorbing thin film with large crystal grains and desirable [hk1] orientation, presenting considerable thin‐film photodetector performance. Furthermore, aluminum (Al 3+ ) cation dopant is introduced to modify the optoelectronic properties of CdS buffer layer, and further optimize the Sb 2 Se 3 /CdS (Al) heterojunction interface quality. Thanks to the suppressed carrier recombination and enhanced carrier transport kinetics, the champion Mo/Sb 2 Se 3 /CdS (Al)/ITO/Ag photodetector exhibits self‐powered and broadband characteristics, accompanied by simultaneously high responsivity of 0.9 A W −1 (at 11 nW cm −2 ), linear dynamic range of 120 dB, impressive ON/OFF switching ratio over 10 6 and signal‐to‐noise ratio of 10 9 , record total noise determined realistic detectivity of 4.78 × 10 12 Jones, and ultra‐fast response speed with rise/decay time of 24/75 ns, representing the top level for Sb 2 Se 3 ‐based photodetectors. This intriguing work opens up an avenue for its self‐powered broadband photodetector applications.