An energy-harvesting scheme utilizing Ga-rich CuIn_(1-x)Ga_xSe₂ quantum dots for dye-sensitized solar cells

Ga-rich CuIn_(1-x)Ga_xSe₂ (CIGS) quantum dots (QDs) with a wide bandgap of 1.58 eV were utilized in dye-sensitized solar cells for energy harvesting. Ga-rich CIGS QDs at TiO₂ photoanodes afford the recombination reduction and thus suppress the dark current, leading to the increase of short-circuit current from 14.47 to 15.27 mA·cm^-2 and open-circuit voltage from 751 to 762 mV. This is due to well-adjusted conduction band minimum of Ga-rich CIGS QDs between that of TiO₂ and excited state oxidation potential of N719, enhancing the photoelectron collection and suppressing electron back-transfer from TiO₂ to oxidized redox species in the electrolyte.