Se-Elemental Concentration Gradient Regulation for Efficient Sb 2 (S,Se) 3 Solar Cells With High Open-Circuit Voltages.

Antimony selenosulfide (Sb 2 (S,Se) 3 ), featuring large absorption coefficient, excellent crystal structure stability, benign non-toxic characteristic, outstanding humidity and ultraviolet tolerability, has recently attracted enormous attention and research interest regarding its photoelectric conversion properties. However, the open-circuit voltage (V oc ) for Sb 2 (S,Se) 3 -based photovoltaic devices is relatively low, especially for the device with a high power conversion efficiency (η). Herein, an innovative Se-elemental concentration gradient regulation strategy has been exploited to produce high-quality Sb 2 (S,Se) 3 films on TiO 2 /CdS substrates through a thioacetamide(TA)-synergistic dual-sulfur source hydrothermal-processed method. The Se-elemental gradient distribution produces a favorable energy band structure, which suppresses the energy level barriers for hole transport and enhances the driving force for electron transport in Sb 2 (S,Se) 3 film. This facilitates efficient charge transport/separation of photogenerated carriers and boosts significantly the V oc of Sb 2 (S,Se) 3 photovoltaic devices. The champion TA-Sb 2 (S,Se) 3 planar heterojunction (PHJ) solar cell displays an considerable η of 9.28 % accompanied by an exciting V oc rising to 0.70 V that is currently the highest among Sb 2 (S,Se) 3 -based solar cells with efficiencies exceeding 9.0 %. This research is anticipated to contribute to the preparation of high-quality Sb 2 (S,Se) 3 thin film and the achievement of efficient inorganic Sb 2 (S,Se) 3 PHJ photovoltaic device.