Ambient Fabrication of 126 μm Thick Complete Perovskite Photovoltaic Device for High Flexibility and Performance

To reap the benefit of low-cost and high-efficiency perovskite photovoltaic devices is to establish a continuous ambient fabrication of device by rapid solution coating without energy- and time-consuming processes such as dry oxygen-free atmosphere and high temperature treatments. Today, an increasing number of wireless devices in consumer electronics and the Internet of Things is creating a large demand for lightweight power sources. Implementation of a plastic film or tape as an extremely lightweight photovoltaic device extends versatile applications of the film device if high mechanical stability is guaranteed. Here, we report a continuous ambient and low-temperature method to fabricate a thin film photovoltaic device comprising a triple cation perovskite absorber Cs 0.05 (FA 0.83 MA 0.17 ) 0.95 Pb(I 0.83 Br 0.17 ) 3 and a mesoporous TiO 2 scaffold. An extremely light 126 μm thick photovoltaic device was fabricated under the ambient humidity of 15–25%. With the best power conversion efficiency of 18%, the flexible device showed mechanical stability against more than 1,000 times bending (radius as low as 5 mm), retaining 90% of its initial efficiency. We found that introduction of a short preheating process on the TiO 2 -coated plastic film before perovskite crystallization effectively reduced thermal expansion stress leading to large grain growth and high coverage of the perovskite absorber.