• A low-temperature (120°C) hydrothermal CdCl 2 treatment is developed for Sb 2 Se 3 /CdS interfaces. • The dual-function mechanism passivates both Cd and S vacancies synergistically. • Treated CdS shows a high Hall mobility of 364.9 cm 2 V -1 s -1 , increased from 145.8 cm 2 V -1 s -1 . • The champion Sb 2 Se 3 solar cell achieves a PCE of 10.49%, a significant boost from 7.30%. • Favorable “spike-like” band alignment and suppressed deep-level traps are achieved. Sb 2 Se 3 , an earth-abundant, environmentally benign photovoltaic absorber, is constrained by interfacial defects, particularly at the CdS buffer layer prepared by chemical bath deposition. Conventional high-temperature (∼400°C) CdCl 2 treatment, while effective, induces detrimental deep Cd 2+ diffusion. Here, we develop a low-thermal-budget hydrothermal post-treatment involving CdCl 2 at 120°C followed by a brief 200°C activation. This strategy synergistically passivates interfacial defects: Cd 2+ fills cadmium vacancies (V Cd ) and Cl⁻ dopes the lattice, concurrently driving the CdS phase transition from cubic to high-mobility hexagonal structure. Consequently, the CdS electron mobility surges from 145.8 to 364.9 cm 2 V -1 s -1 , and the CdS/Sb 2 Se 3 band alignment is optimized to a favorable spike-like configuration (+0.11 eV). The treated substrate-configurated solar cells achieve a champion power conversion efficiency of 10.49%, a 44% improvement from the 7.30% of control devices, with enhanced open-circuit voltage, short-circuit current, and fill factor. This work demonstrates a dual-passivation, low-temperature interface engineering route that suppresses defect formation while promoting carrier transport, providing a viable strategy for high-efficiency Sb 2 Se 3 photovoltaics.
贾传铃 et al. (Fri,) studied this question.