Novel synthesis of Cu₂CoSnS₄-carbon quantum dots nano-composites potential light absorber for hybrid photovoltaics

A novel and simple synthesis of the absorber layer is indispensable in order to reduce the cost and processing of quantum solar cells. In this work, we developed novel Cu₂CoSnS₄-carbon quantum dot (CCTS:CQD) nano-composite as an absorbing material for solar cell applications. CCTS:CQD nano-composites were prepared by direct pyrolysis of CCTS precursors and citric acid. The proportions of citric acid precursor to CCTS were varied from 0.1 to 0.7. The properties of the synthesized nano-composite were studied using a UV–vis spectrophotometer in the wavelength range of 300–900 nm. CCTS:CQD has a property of dynamic photoluminescence that depends on the excitation wavelength. The results of the x-ray diffraction revealed that the CCTS:CQD nano-composites were predominantly polycrystalline in nature. The formation of CCTS:CQD was confirmed by a high-resolution transmission electron microscope (HRTEM), which exhibits the size ∼3 nm. The thin films of CCTS:CQD nano-composites were deposited on glass/ITO substrates by spray pyrolysis technique at 170 °C. Current–voltage (I–V) measurements carried out in dark and light conditions revealed CCTS: CQD thin films with good photo-response. The purpose of the present study is to develop CCTS: CQD nano-composite p-type absorber layer suitable for thin film solar cells. (paper)