Advances in Top Transparent Electrodes by Physical Vapor Deposition for Buffer Layer-Free Semitransparent Perovskite Solar Cells

The advancements in halide perovskite materials, celebrated for their exceptional optoelectronic properties, have not only led to a remarkable increase in the efficiency of perovskite solar cells (PSCs) but also opened avenues for the development of semitransparent devices. Such devices are ideally suited for integration into building facades and for use in tandem solar cell configurations. However, depositing transparent electrodes (TEs) on top of the charge transport layers in PSC poses significant challenges. Physical vapor deposition (PVD), commonly used in the industry to prepare transparent conducting oxides (TCOs) as TEs, can introduce plasma-induced damage during the process, which decreases the efficiency of the final devices. While incorporating a buffer layer is the typical approach to mitigate plasma damage, it also increases the complexity and costs of solar cell fabrication. This perspective focuses on the developments of buffer-free semitransparent PSCs. It highlights the shift away from the typical approach of incorporating a buffer layer. Through a comprehensive analysis of recent research, this work presents successful cases of direct TCO deposition onto transport layers, evaluates scalability and stability, and concludes with recommendations for optimizing PVD processes in the fabrication of buffer-free PSCs.