Thermal Stability and Mechanical Toughness of Laminated Perovskite Solar Cells

Laminated perovskite solar cells (L-PSCs), which can be fabricated by independently processing the hole and electron transport sides of the solar cell on separate substrates and then bonding them together, offer unique passivation, transport, and contact-layer combinations. Lamination also facilitates inherent self-encapsulation between two glass substrates, which can be leveraged to improve stability. However, the impacts of this glass-glass encapsulation on the mechanical properties and thermal stresses that arise during operation have not been previously studied. Here, we measured the thermal cycling stability and interfacial toughness of L-PSCs for the first time. L-PSCs withstood thermal cycling (TC50 protocol, -40 to 85 °C) without failure, with all devices exhibiting an increase in power conversion efficiency after cycling. To quantify their mechanical properties, the interfacial toughness values of device stacks were measured, and minimal changes were observed after TC50 cycling. An analytical framework was developed to describe the mechanical failure criterion for the self-encapsulated L-PSC system under thermal cycling, showing that using substrates with the same material properties on both sides makes the device system robust to thermal cycling. This study demonstrates that L-PSCs exhibit strong thermal and mechanical stability without the need for additional encapsulation.