Simple Encapsulation Method for Flexible Perovskite Solar Cells with Transparent Electrode‐Integrated Barrier Films

Flexible perovskite solar cells (PSCs) have been rapidly developed for realistic applications such as windows and auxiliary power supplies of electronics. However, the moisture penetration through the flexible substrate films still poses a major obstacle because it can destroy the perovskite films under outdoor conditions. Unlike conventional PSCs with glass‐based encapsulation, flexible PSCs face challenges in finding suitable materials and structures that maintain flexibility while providing effective encapsulation. Simple encapsulation methods for flexible PSCs are proposed using a transparent electrode‐integrated flexible barrier (TIFB) substrate comprising silicon nitride (SiN x )/polyethylene terephthalate (PET)/indium tin oxide (ITO). A dense SiN x layer with chemical vapor deposition on ITO–PET films is deposited and a more flexible TIFB than the conventional laminated substrate owing to its thinness is achieved. TIFB shows a low water vapor transmission rate of 4.3 × 10 −3 g m −2 day. Consequently, the efficiency of TIFB‐based PSCs under harsh conditions (60 °C and 90RH%) exhibits an acceptable decrease within 10% of its highest efficiency after 400 h, which is the most stable data under high temperature and humidity among existing flexible encapsulated PSCs. TIFB, as a flexible substrate, is a major candidate to protect flexible electronics and PSCs against external factors.