The efficiency of Cu₂ZnSnS₄ (CZTS) solar cells is limited due to interfacial band misalignment and severe non-radiative recombination. ZnSnO (ZTO) is a promising Cd-free buffer layer, offering a potential for favorable band alignment with CZTS absorber. Here, we demonstrate that optimizing the temperature-dependent deposition during reactive magnetron sputtering significantly promotes elemental interdiffusion. For the proposed CZTS/ZTO interface, a favorable “spike-like” band alignment is achieved, effectively enhancing the carrier transport efficiency and reducing the interfacial defect density. Furthermore, Zn diffusion mitigates Cu_Zn (that is, copper atoms sit at sites normally occupied by zinc atoms) antisite defects, reducing the non-radiative recombination and improving the absorber quality. Finally, the champion device achieved the highest power conversion efficiency (PCE) of 10.90% by sputtering ZTO as buffer layer in CZTS solar cell so far, with a high open circuit voltage (V_OC) of 740 mV and a fill factor (FF) of 61.79%. This strategy highlights the potential of sputtered ZTO as a scalable and eco-friendly buffer layer for Cd-free CZTS solar cells.

Antimony selenide (Sb₂Se₃) is an emerging semiconductor material with significant potential for a range of photoelectric applications due to its favorable physical properties, including high stability, non-toxicity, an optimal bandgap, and high absorption coefficient. This review focuses on the latest advancements in the fabrication, material properties, and diverse applications of Sb₂Se₃, extending beyond photovoltaic uses to photodetectors, photocathodes, and other optoelectronic devices. The unique one-dimensional crystal structure of Sb₂Se₃ offers intrinsic anisotropic charge transport, making it highly adaptable for next-generation devices. We highlight the various deposition methods employed, such as hydrothermal, chemical bath deposition (CBD), vapor transport deposition (VTD), and close-spaced sublimation (CSS), each playing a crucial role in optimizing material quality. Additionally, this review discusses the primary challenges, including defect engineering and interface optimization, that must be addressed to fully realize the potential of Sb₂Se₃-based devices. Finally, this review presents some future directions for enhancing device performance, with particular emphasis on material synthesis and device architecture improvements that can drive further innovation in this field.

Antimony selenide (Sb₂Se₃) has recently made considerable advancements in photovoltaic, photoelectrochemical, and photodetector research scenarios, owing to its advantageous material merits and superior optoelectronic properties. By contrast, the exploration of flexible Sb₂Se₃ photoelectric devices are less attempted, though it possesses unique one-dimensional (1D) crystal structure to enable large deformation tolerance. Here, we develop a flexible Sb₂Se₃ thin-film photodetector on polyimide substrate. Thanks to the high-quality Sb₂Se₃ light absorber and benign interfaces at both back contact and heterojunction regions, the carrier dynamics are effectively optimized. The leading flexible Sb₂Se₃ photodetector showcases self-powered and broadband features, with exceptional responsivity of 0.51 A·W^–1 and realistic detectivity up to 1.32 × 10¹³ Jones, ultra-fast response speed of 49 ns/351 ns of rise and decay times, and remarkable mechanical deformation stability, flourishing the high-level development for flexible Sb₂Se₃ photodetectors. Interestingly, a tunable single/dual-color flexible imaging system under band alignment modulation, along with a wearable and accurate heart rate/arterial blood oxygen saturation photoplethysmography detection system highlights the great application potential for flexible Sb₂Se₃ photodetectors.