Antimony selenide (Sb₂Se₃) is a promising candidate for photodetector applications boasting unique material benefits and remarkable optoelectronic properties. Achieving high‐performance self‐powered Sb₂Se₃ 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 Sb₂Se₃ light absorbing thin film with large crystal grains and desirable [hk1] orientation, presenting considerable thin‐film photodetector performance. Furthermore, aluminum (Al³⁺) cation dopant is introduced to modify the optoelectronic properties of CdS buffer layer, and further optimize the Sb₂Se₃/CdS (Al) heterojunction interface quality. Thanks to the suppressed carrier recombination and enhanced carrier transport kinetics, the champion Mo/Sb₂Se₃/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 10⁶ and signal‐to‐noise ratio of 10⁹, record total noise determined realistic detectivity of 4.78 × 10¹² Jones, and ultra‐fast response speed with rise/decay time of 24/75 ns, representing the top level for Sb₂Se₃‐based photodetectors. This intriguing work opens up an avenue for its self‐powered broadband photodetector applications.

Antimony selenide (Sb₂Se₃) is an ideal photovoltaic candidate profiting from its advantageous material characteristics and superior optoelectronic properties, and has gained considerable development in recent years. However, the further device efficiency breakthrough is largely plagued by severe open‐circuit voltage (V_OC) deficit under the existence of multiple defect states and detrimental recombination loss. In this work, an effective absorber layer growth engineering involved with vapor transport deposition and post‐selenization is developed to grow Sb₂Se₃ thin films. High‐quality Sb₂Se₃ with large compact crystal grains, benign [hk1] growth orientation, stoichiometric chemical composition, and suitable direct bandgap are successfully fulfilled under an optimized post‐selenization scenario. Planar Sb₂Se₃ thin‐film solar cells with substrate configuration of Mo/Sb₂Se₃/CdS/ITO/Ag are constructed. By contrast, such engineering effort can remarkably mitigate the device V_OC deficit, owing to the healed detrimental defects, the suppressed interface and space‐charge region recombination, the prolonged carrier lifetime, and the enhanced charge transport. Accordingly, a minimum V_OC deficit of 0.647 V contributes to a record V_OC of 0.513 V, a champion device with highly interesting efficiency of 7.40% is also comparable to those state‐of‐the‐art Sb₂Se₃ solar cells, paving a bright avenue to broaden its scope of photovoltaic applications.