Sputtering under Mild Heating Enables High-Quality ITO for Efficient Semi-Transparent Perovskite Solar Cells

Abstract

Semi-transparent perovskite solar cells (ST-PSCs) are promising in building-integrated photovoltaics (BIPVs) and tandem solar cells (TSCs). One of the keys to fabricate high-performance ST-PSCs is depositing efficient transparent elec-trodes. Indium tin oxide (ITO) is an excellent transparent conductive oxide with good light transmittance and high conductivity. However, the high sheet resistance of ITO sputtered at room temperature leads to the low fill factor (FF) and poor power conversion efficiency (PCE) of the ST-PSCs. Here, we study the effect of the sputtering temperature on the properties of ITO and the performance of ST-PSCs. We find that when the sputtering temperature increases from the room temperature to 70°C, the crystallinity of the sputtered ITO gradually improves. Therefore, the sheet resistance decreases and the corresponding device performance improves. However, once the sputtering temperature further increases over 70°C, the underlying hole transport layer will be damaged, leading to poor device performance. Therefore, the optimized mild heating temperature of 70°C is applied and we obtain ST-PSCs with a champion PCE of 15.21%. We believe this mild heating assisted sputtering method is applicable in fabricating BIPVs and TSCs.