Beyond Substrate Engineering: Thermal‐Kinetic Control Breaks the Crystallization Bottleneck in Quasi‐1D Sb 2 (S,Se) 3 Photovoltaics

ABSTRACT The performance of quasi‐one‐dimensional (Q1D) Sb 2 (S,Se) 3 photovoltaics is often hindered by its unfavorable crystallographic orientation that limits charge transport. Despite advances in substrate engineering, orientation control has largely been pursued through isolated parameters, and a holistic strategy that integrates multiple factors remains absent. Herein, we break this bottleneck by demonstrating that thermal‐kinetic modulation during post‐annealing, together with substrate engineering, offers a decisive route for achieving preferred crystallographic orientation. By employing a rapid heating process, we actively regulate the crystallization kinetics on moderately inducing substrates, which promotes the vertical growth of (Sb 4 X 6 ) n ribbons and thus secures a highly oriented (hk1) texture. This approach yields a champion device with a power conversion efficiency (PCE) of 9.35%, primarily attributed to improved charge collection efficiency enabled by the vertically oriented Sb 2 (S,Se) 3 , along with a partial contribution from suppressed deep‐level defect recombination. This work represents a significant step from passive substrate reliance to active thermal‐kinetic control, offering a novel and general strategy for mastering crystallization in Q1D and analogous photovoltaic materials.