Considerably Improved Photovoltaic Performances of ITO/Si Heterojunction Solar Cells by Incorporating Hydrogen Into Near-Interface Region

High-efficiency and low cost are always the goals pursued by the photovoltaic industry. However, silicon-based heterojunction solar cells with the highest efficiency of 26.7% are based on a complex preparation process that inevitably results in an increase in costs. Among them, indium tin oxide (ITO) film usually plays the role of antireflection, light transmission, and transport of charge carries, rather than one of the carrier-selective contacts in the p-n junction. In this article, ITO/Si heterojunction solar cell is fabricated in which ITO thin film is applied to the Si-based heterojunction solar cells as a function of hole-selective contact. Furthermore, by incorporating hydrogen into the near interface of the ITO/Si heterojunction, we obtained a significant enhancement of device performances. It is found that the postannealing leads to the increase of the resistance of ITO materials and the decrease of the fill factor (FF) of ITO/Si solar cell devices, but the incorporation of hydrogen could contribute to a postannealing degradation of the resistance of ITOH and an enhancement of the FF of ITOH/Si solar cell devices. Finally, a maximum power conversion efficiency (PCE) of 17.5% for ITO/ITOH/Si heterojunction solar cell is obtained.