Effect of residual water vapor on the performance of indium tin oxide film and silicon heterojunction solar cell

Abstract

In this study, we investigate the effect of residual H2O pressure (PH2O) on the structural, electrical, and optical properties of indium tin oxide (ITO) film and the current-voltage (I-V) performance of silicon heterojunction (SHJ) solar cells. The ITO films and SHJ solar cell were prepared under different PH2O (3.75 × 10−7 Pa, 6 × 10−7 Pa, 10.25 × 10−7 Pa) by varying the pumping time before starting the fabrication process. The experimental results revealed the crystallinity of ITO films was suppressed with the increase in PH2O. Further, the sheet resistance of ITO films was reduced from 103 Ω/sq to 60 Ω/sq due to the enhanced carrier mobility, and the transmittance in near- infrared (NIR) region exhibited a slight increase, but the conversion efficiency of SHJ solar cells dropped dramatically from 23.3% to 22.79% due to the degradation of fill factor (FF). The analysis on n-a-Si:H/ITO and ITO/Ag contact properties indicated that such FF degradation could be attributed to the increased specific contact resistance for the two contacts, when PH2O was high. Finally, SHJ solar cell with conversion efficiency of 23.53% was achieved by restraining the residual H2O vapor during ITO deposition along with the optimization of transmittance in NIR region by adjusting the amount of O2 flow.