Stress-Compensated, Deformation-free Indium Tin Oxide Bilayer Electrodes for Ultrathin Flexible Perovskite Solar Cells

Abstract The high electrical conductivity and optical transparency of indium-tin-oxide (ITO) make it an ideal electrode material for optoelectronic devices such as solar cells and light-emitting diodes. However, when ITO electrodes are fabricated on very thin plastic substrates, internal stress in the ITO layer causes wrinkles to form in the flexible plastic film. In this work, we show that stress-compensated ITO bilayers composed of an amorphous base layer and a crystalline overlayer lead to deformation-free ITO electrodes. Using these ITO bilayers deposited on 4 µm polyethylene naphthalate films, perovskite solar cells reached a power conversion efficiency (PCE) of 18.2% with a power-to-weight ratio of 24 W g − 1 . Under indoor lighting (White LED, 200 lux, 5000 K), the PCE reached 28.3%. The devices retained 95% of the original PCE after 1000 bend cycles. A 3-cell module with a designated area of 2.3 cm 2 was realized with a power output of 28.1 mW and an open circuit voltage of 3.17 V.