Simulation approach for optimization of device structure and thickness of HIT solar cells to achieve ∼27% efficiency

Optimization of thicknesses of n-type a-Si:H emitter layer, front a-Si:H i-layer and p-type c-Si base wafer as well as optimum heterojunction (HJ) and HJ with intrinsic layer (HIT) solar cells are performed using AFORS-HET simulation software. By optimization, we realized record efficiency of 27.02% in bifacial HIT solar cell at emitter layer, front i-layer and c-Si base wafer thicknesses of 6 nm, 3 nm and 200 mu m, respectively. Interestingly when the thickness of c-Si wafer was reduced to 58 mu m, while keeping the thicknesses of emitter and front i-layers as same as 6 nm and 3 nm, respectively, efficiency in bifacial cell got reduced to 26.45%. All cell structures generated highest efficiency at emitter layer and front i-layer thicknesses of 6 nm and 3 nm, respectively. However, optimum c-Si base wafer thickness was varied according to the following cell structures: simple HJ and HIT cells showed highest efficiency at 300 mu m, HJ with BSF layer cell at 98 mu m, HIT with BSF layer at 58 mu m. It is worth mention that, efficiency in bifacial cell at 58, 98 and 200 mu m was varied nominally. These optimizations may help in producing low cost high efficiency HJ and HIT solar cells technology. (c) 2012 Elsevier Ltd. All rights reserved.