Efficiency enhancement of silicon solar cells by silicon quantum dots embedded in ZnO films as down-shifting coating

Abstract

In the present work, the incorporation of silicon quantum dots (SiQDs) in zinc oxide (ZnO) films to develop coatings that improve the efficiency of silicon solar cells is reported. The down-shifting conversion of the SiQDs was used to enhance the efficiency of a photovoltaic device. The room temperature spectrum centered at 510 nm (2.43 eV) for the SiQDs is shown. The transmittance of the SiQDs-ZnO samples was measured and the band gap (Eg) was estimated through Tauc’s method. An increase on the band gap from 3.35 to 3.55 eV as function of the incorporation of SiQDs was obtained. The influence of the SiQDs in the oxide crystallinity of the wurtzite structure was studied through the X-ray diffraction. To determine the current increase under a standard test condition (STC) was achieved and an overall efficiency of 17.58% was obtained using a SiQDs-ZnO coating on silicon solar cells. The synergistic effect of SiQDs addition to ZnO films was demonstrated.