Optimization of a CNT-based SiGe Thin Film Solar Cell Structure

In this paper, a SiGe thin film solar cell structure based on the carbon nanotube (CNT) and with a back surface field (BSF) layer is proposed. The efficiency of this structure is 40.36%, which is higher than conventional structures without CNT layer. We optimize this structure by changing the base layer thickness and determining the ratio of the width of the upper contact to the width of the entire cell. The cell efficiency after this optimization reaches 41.08%. Furthermore, the performance of this cell is evaluated using two types of CNT layers with sheet resistances of 128 Ω/□ and 76 Ω/□. The results of numerical simulation show that the SiGe thin film solar cell using CNT layer with 128 Ω/□ sheet resistance has better performance parameters. Finally, the number of metal electrodes above the cell is optimized due to the shading effect and we show that the contact distance in the presence of CNT layer can be increased up to 2000 µm.