Flexible and Highly Durable Perovskite Solar Cells with a Sandwiched Device Structure

Flexible perovskite solar cells (PSCs) have been quickly developed as the most promising candidates for low-cost photovoltaic technology. However, the bendable and foldable properties of PSCs induce the decrease of their efficiencies. In this paper, we report the design of a new kind of flexible PSCs with a sandwiched structure. The critical layer of the flexible device is designed at a neutral layer of the sandwiched structure, which is stress-free, no matter how the device bending is. During the bending test, sandwich-structured flexible PSCs showed extremely long bending lifetime, which is at least 5-8 times higher than that of generally reported devices. At the same time, the sandwiched structure works as the encapsulation effect. The flexible device with a sandwiched structure greatly improves the device's long-term stability. Therefore, the designed sandwiched structure significantly promotes the bending ability and stability of flexible PSCs.