Ag2Se quantum-dot sensitized solar cells for full solar spectrum light harvesting

We report on the photovoltaic performance of Ag₂Se quantum-dot (QD) sensitized solar cells. The QDs are grown by the successive ionic layer adsorption and reaction process. The external quantum efficiency (EQE) spectrum of the assembled cells covers the entire solar power spectrum of 350-2500 nm with an average EQE of ∼80% in the short-wavelength region (350-800 nm) and 56% over the entire solar spectrum. The effective photovoltaic range is ∼7-14 times broader than that of the cadmium calcogenide system—CdS and CdSe. The photocurrent that Ag₂Se generates is four times higher than that of N3 dye. The best solar cell yields power conversion efficiencies of 1.76% and 3.12% under 99.4% and 9.7% sun, respectively. The results show that Ag₂Se QDs can be used as a highly efficient broadband sensitizer for solar cells.