dc.description.abstract | Heterojunction with Intrinsic Thin layer (HIT) solar cells have some advantages about low temperature, low power, high open circuit voltage, and good temperature coefficient. They are better than Diffusion cells. In this study, ECRCVD was used for the deposition of high doping silicon thin films, and PECVD was used for the deposition of high doping silicon thin films and passivation layers. These thin films were deposited on single-crystalline silicon substrate to fabricate the silicon hetero-junction solar cells. The optical properties, electrical properties, and solar cell performance of hetero-junction solar cells were investigated. ECRCVD has advantage about high deposition, low working pressure, low ion bombardment, and no electrode contamination. The boron-doped layer was deposited by ECR as emitter in HIT solar cells. On the other hand, the high quality passivation layers and the back surface field of phosphorus-doped layer were deposited by PECVD to fabricate the silicon hetero-junction solar cells.
We will investigate the optimization of carrier lifetime, different passivation layer, different wafer thickness, different doping layer, and different texture wafers. First, we are going to improve Voc and investigate the carrier lifetime with the structure of pi-ip and ni-in. The structure of HIT solar cell is Ag/ITO/a-Si:H(p)/a-Si:H(i)/c-Si(n)/a-Si:H(i)/a-Si:H(n)/ITO /Ag. The characteristics of hetero-junction solar cell on n-type planar substrate with the 10 nm-thick passivation layer are shown as follow: Voc = 690 mV in the area of 1 cm2. Moreover, the different thickness of wafers varying from 180 μm to 50 μm were also investigated. For 50 μm-thick substrate, the characteristics of hetero-junction solar cell on n-type planar substrate were shown as follow: surface recombination rate: 6 cm/s, Voc = 651 mV, Jsc = 29.28 mA/cm2, F.F. = 65.40 %, Efficiency = 12.46 %. This result is outstanding, therefore we will continue to research the HIT solar cells with ultra-thin substrates in the future. In our study, using the 20 nm-thick doping layer as emitter can achieve good conversion efficiency. In the end, we modulate the different textured wafers for HIT solar cells. The characteristics of 200 μm-thick hetero-junction solar cell with the grain size around 3~5 μm on n-type textured substrate are shown as follow: Voc = 660 mV, Jsc = 36.7 mA/cm2, F.F. = 71.1 %, Efficiency = 17.2 %.
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