Encapsulation of Printable Mesoscopic Perovskite Solar Cells Enables High Temperature and Long‐Term Outdoor Stability

Perovskite solar cells (PSCs) have achieved high power conversion efficiency on the lab scale, rivaling the other commercialized photovoltaic technologies. However, stability issues have made it difficult for PSCs to achieve comparable or practical lifetimes in outdoor applications. Here, three different types of hot melt films (polyurethane, PU; polyolefin, POE; and ethylene vinyl acetate, EVA) together with glass sheets are employed to encapsulate printable PSCs. The influence of thermal stress and the encapsulation (lamination) process on cell performance is investigated. It is found that POE and EVA, which are the typical encapsulants for silicon and thin film solar cells, are not suitable for the encapsulation of PSCs due to a high laminating temperature (>130 °C) or corrosion of the perovskite absorber. By contrast, encapsulation with PU can be carried out at a relatively mild temperature of 80 °C, and significantly enhance the thermal stability of the cells. When this encapsulation method is applied to large‐area (substrate area 100 cm2) printable PSC submodules, the submodules can maintain 97.52% of the initial efficiency after 2136 h under outdoor conditions (location: 39°19′48″N 114°37′26″E). This work demonstrates the potential of industrially relevant encapsulation techniques to enable the commercial viability of PSCs. Encapsulation enables long‐term outdoor stability in real operating environments for printable mesoscopic perovskite solar cells toward potential commercialization.