Nanohole structures for efficiency enhancement in thin film photovoltaics

Nanohole structures were implemented at various layers in amorphous silicon thin film solar cells designed using 2D and 3D CAD software. Electrical and optical properties of the photovoltaic cell are obtained by modeling such structures using solar cell utility packages. Absorption improvement and thereby conversion efficiency improvement have been achieved over the 300 to 600nm solar spectrum. In this paper, nanoholes were been placed on the glass substrate/ transparent conducting oxide layer/ amorphous silicon layer of the thin film solar cell and the performances of the devices were compared. Better performance was found in the case where the nanoholes were placed in the amorphous silicon layer. We found that nanohole diameter, depth into the respective layer and the pitch between various holes play important roles in determining the final conversion efficiency. The fabrication of nanoholes on glass, TCO and silicon surfaces of these solar cell designs is also discussed.