Benign Solution-Processed Sb2se3 Nanowires for Photovoltaic Applications

Antimony selenide (Sb2Se3) has been considered a potential candidate for a solar cell absorber material because of its suitable bandgap and high absorption coefficient. However, Sb2Se3 is usually deposited by vacuum-based methods at >400°C. Solution-based methods offer an intriguing alternative as the deposition temperature can be reduced, enabling the use of heat-sensitive substrates and the solid composition can be tuned with soluble additives. In recent years, the utilization of amine-thiol solvent mixture for the dissolution of metals and chalcogens has gained attractiveness as an alternative to hydrazine. Nevertheless, the corrosivity of the solvents remains a major hurdle for coating on other sensitive layers, such as selective transport layers. Here in this work, we report a benign solution approach where first Sb and Se are dissolved in ethylenediamine (en) and 1,2-ethandithol (EDT) solvent to form the Sb-Se-metal-organic complex. Then, the Sb-Se-complex is isolated by vacuum evaporation of the solvents and re-dissolved in a benign solvent [dimethyl sulfoxide (DMSO)] to form an Sb-Se-ink. The utility of this technique is demonstrated by the fabrication of Sb2Se3 nanowires by spin-coating the Sb-Se-complex solution followed by mild heat treatment. We have found that the crystallization of Sb2Se3 onset at ~100°C and processing at ~150°C results in completely crystalline Sb2Se3 nanowires. The applicability of the developed method has been demonstrated by incorporating it in FTO/ZnO/CdS/Sb2Se3/Spiro-OMeTAD/Au solar cell structure.