Se-Elemental Concentration Gradient Regulation for Efficient Sb2(S,Se)3 Solar Cells with High Open-Circuit Voltages.

ABSTRACT

Antimony selenosulfide (Sb2(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 (Voc) for Sb2(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 Sb2(S,Se)3 films on TiO2/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 Sb2(S,Se)3 film. This facilitates efficient charge transport/separation of photogenerated carriers and boosts significantly the Voc of Sb2(S,Se)3 photovoltaic devices. The champion TA-Sb2(S,Se)3 planar heterojunction (PHJ) solar cell displays an considerable η of 9.28% accompanied by an exciting Voc rising to 0.70 V that is currently the highest among Sb2(S,Se)3-based solar cells with efficiencies exceeding 9.0%. This research is anticipated to contribute to the preparation of high-quality Sb2(S,Se)3 thin film and the achievement of efficient inorganic Sb2(S,Se)3 PHJ photovoltaic device.