Facile and Novel Chemical Synthesis, Characterization, and Formation Mechanism of Copper Sulfide (Cu2S, Cu2S/CuS, CuS) Nanostructures for Increasing the Efficiency of Solar Cells

This paper reports the successful synthesis of various copper sulfide nanostructures via coprecipitation and hydrothermal routes using new starting reagents such as Na2SO3 as a reducing agent for converting Cu2+ to Cu+ and PMP dye–Cu(II) and carminic acid–Cu(II) complexes as new copper precursors for synthesizing quantum dots in aqueous medium. The as-synthesized products were extensively characterized by techniques including XRD, EDS, SEM, TEM, AFM, and DRS. Effects of different parameters such as temperature, surfactant, solvent, concentration, copper precursor, sulfide source, etc., on morphology and particle size of as-synthesized nanostructures were investigated. Moreover, the efficiency of various as-synthesized nanostructures in thin layer solar cells was evaluated. The results showed that particle size and morphology have a salient effect on solar cell efficiency. Also, utilizing prepared Cu2S quantum dots as a barrier layer in dye-sensitized solar cells (DSSCs) presented a remarkable increase in the efficiency of solar cells from 6.08% to 8.34% (∼37% improvement).