<p>Antimony selenide (Sb₂Se₃) is a promising photovoltaic material due to its high absorption coefficient and favorable mobility. However, its long-term stability and defect dynamics remain insufficiently explored. In this study, Sb₂Se₃ thin films were fabricated via magnetron sputtering, with post-deposition annealing used to induce a transition from an amorphous (Sb-1 film) to a crystalline orthorhombic phase (Sb-2 film). We systematically investigated the impact of ambient air, oxygen, UV irradiation, and light-soaking on the electronic properties of these films. Key findings reveal that oxygen exposure increases dark conductivity (σ_D) by approximately one order of magnitude, a process largely reversible under vacuum for both phases. In contrast, radiative aging induced divergent responses: while amorphous film showed transient responses, crystalline samples exhibited complex and partially irreversible defect dynamics. Specifically, UV irradiation and long-term atmospheric exposure induced permanent shifts in the mobility-lifetime (mt) product of crystalline film, indicating alterations in dominant recombination pathways. Furthermore, mt products increased during light-soaking, suggesting the activation of metastable states. These results provide critical insights into phase-dependent environmental sensitivity, highlighting that precise crystallinity control and encapsulation are paramount for Sb₂Se₃ device stability.</p> Graphical Abstract <p></p>