Abstract:

Antimony doped tin oxide (ATO), as one kind of transparent conductive oxides (TCO), is applied as electrodes in thin film solar cells. On the basis of the traditional glass/TCO structure on top of amorphous silicon thin-film solar cells, graphene is introduced to form a three layer structure, which is aimed at both enhancing the optical absorption of thin-film solar cells as an antireflection coating (ARC) and increasing the electrical conductivity as a TCO electrode. In this paper, SiO2/ATO with graphene layer structure is selected for the optimal light-trapping design by using differential evolution method. The effect of graphene, including the stacking position and graphene layer numbers, is mainly investigated and the thickness of the layers of proposed structure is optimized to enhance the optical absorption of thin-film solar cells to the greatest degree. The theoretical calculation results clearly demonstrate that the proposed SiO2/ATO/Graphene layered structure is obviously superior to the SiO2/Graphene/ATO structure, and it can obtain a higher light-trapping enhancement over a wide range of incident angles and wavelengths because of the graded refractive index distribution profile.