Highly efficient flexible perovskite solar cells made via ultrasonic vibration assisted room temperature cold sintering

Abstract

With emerging flexible substrates, perovskite solar cells have entered into a new stage of development toward flexibility, portability and miniaturization. However, this promising landscape is hindered by the necessity the high-temperature processes. In this study, a highly efficient, stable and flexible planar perovskite solar cell is fabricated using an all-room temperature pathway. First, a nanocrystalline SnO2 layer is deposited on polyethylene terephthalate/indium tin oxide via room-temperature sol-gel strategy. Then (FAPbI3)0.85(MAPbBr3)0.15 is coated thereon, by annealing-free solution deposition. In both steps films are subjected to ultrasonic vibration, right after deposition, while they are still wet. By virtue of the ultrasonic energy, surface evaporation of liquid molecules is accelerated, impurities are removed from deposited wet film, and as a result shrinkage and sintering occur at room temperature. The cell is completed by a classical method, showing a champion power conversion efficiency of 17.38%, based on 0.16 cm2 active area. After 480 h aging in 50% relative humidity, this cell retains 80% of its initial performance. This research promises efficient, inexpensive and sustainable systems for harvesting solar energy by wearable modules.