Moisture-Resistant Electrospun Polymer Membranes for Efficient and Stable Fully Printable Perovskite Solar Cells Prepared in Humid Air

Fully printable perovskite solar cells (PPSCs) attract attention in the photovoltaic industry and research owing to their controllable and scalable production with reduced material waste during manufacturing. However, the commercialization of PPSCs has been impeded by their inherent vulnerability to ambient moisture, leading to a rapid loss of device efficiency and lifetime. Here, we propose a novel idea to enhance the photovoltaic performance and stability of PPSCs in humid air (relative humidity exceeding 80%) using electrospun hydrophobic polymer membranes, i.e., polylactic acid (PLA), polycaprolactone (PCL), and PLA/PCL blends, as moisture-resistant layers for PPSCs. After optimizing the morphologies, hydrophobicity, and thermal properties of the electrospun membranes by varying the contents of the polymer components in the membranes, the unencapsulated devices with these membranes demonstrated power conversion efficiencies of up to 8.2%, which was significantly higher than for devices without the membranes (6.8%). Moreover, devices with the optimum electrospun membrane retained more than 85% of their original efficiency after being stored in humid air for over 35 days. In comparison, devices without the electrospun membranes lost about 50% of their initial efficiency over the same time. Our work is very useful for the development of highly efficient and stable commercial PPSCs.