Flexibility of metal halide perovskite solar cell based on tensile properties

Abstract

The sun is a sustainable, reliable and nearly infinite energy source, and photovoltaic energy is currently drawing attention as an alternative energy source. Hybrid metal halide perovskite solar cells hold promise for nextgeneration photovoltaic devices due to their high light-absorption coefficient and good cost-effectiveness, and the photovoltaic efficiencies of perovskite-based solar cells have rapidly soared from 3.8% to above 20% in less than 10 years. In addition, perovskite devices have recently attracted substantial interest for flexible/stretchable electronic devices due to it can makes thinner. In these various applications, especially flexible solar cells, one of the most important factors in device durability is mechanical properties. Most flexible perovskite solar cells are occurred degradation of photovoltaic properties after severe bending environment. In general, it is known as crack propagation on weakest layer in entire device. However, it is still unclear which mechanisms are suitable to its fracture system. For this reason, estimation of mechanical properties in flexible perovskite solar cell is important. Several researches have studied mechanical properties using computation methods and nanoindentation techniques. Unfortunately, these results are not sufficient to explain mechanical reliability of perovskite devices. It is because no considered various structured defects such as grain boundary and pin-holes. For this reason, here we fabricated various free-standing component thin films of flexible perovskite solar cells using same process as devices. And then we evaluated their elastic deformation limits using nanoindentation on the transferred free standing thin films on hole-substrates. We confirmed that the perovskite layer is by the weakest components. Therefore, we evaluated and analyzed the intrinsic tensile properties of perovskite layers by an in-situ tensile testing system using push-to-pull devices. We believe that this study sheds light on the durability and fundamental mechanism of flexible perovskite solar cells.