Wide bandgap p-type window layer prepared by trimethylboron doping at high temperature for a-Si:H superstrate solar cell

Wide bandgap p-type window layer is necessary for silicon thin film solar cell to obtain excellent performance, such as high open-circuit voltage (VOC), and large short-circuit current density (JSC). Instead of the usually used material, SiCx:H or SiOx:H fabricated by incorporating C or O into the Si matrix, and nc-Si:H deposited at a very low temperature, wide bandgap p-type window layer was realized here by doping with trimethylboron (TMB) at a relatively high temperature via plasma enhanced chemical vapor deposition (PECVD). Excellent performance with VOC larger than 900 mV was achieved for p–i–n superstrate solar cell on SnO2:F coated glass while the p-type window layer was deposited at 200 °C to 250 °C. By investigating the influence of the deposition temperature on the p-layer bandgap and microstructure further, it was found that the compromise between wide bandgap and good quality of the p-layer determined the solar cell performance.