Water-soluble ZnSe/ZnS:Mn/ZnS quantum dots convert UV to visible light for improved Si solar cell efficiency

Abstract

The sensitivity of Si solar cells to the UV portion of the solar spectrum is low, and must be increased to further improve their efficiencies. In this study, water-soluble ZnSe/ZnS:Mn/ZnS core/shell/shell quantum dots (QDs) capable of converting UV into visible light were synthesised by a hydrothermal method. A photoluminescence quantum yield of 84% was achieved by carefully investigating and optimising the QD preparation conditions. Furthemore, we prepared wavelength-conversion glass containing the ZnSe/ZnS:Mn/ZnS QDs dispersed in sol–gel glass and applied it to Si solar cells. As a result, the spectral sensitivity of the Si solar cell at wavelengths shorter than 400 nm was significantly improved, and the amount of power generated (conversion efficiency) was increased by 7.4% compared with that of the cell without the wavelength-conversion glass coating.