Parafilm-assisted fabrication of flexible perovskite solar cells to improve efficiency

Abstract

Flexible perovskite solar cells (f-PSCs) are lightweight and bendable, making them ideal for powering portable and wearable devices on various surfaces and structures. However, the flexibility of the substrate polyethylene naphthalate (PEN) used in f-PSCs makes it challenging to control the morphology of the perovskite layer during the fabrication process, thereby leading to low device performance. Additionally, the difference in thermal expansion between the PEN and other functional layers causes deformation during the heating process. In this work, we demonstrate a promising strategy for fabricating efficient f-PSCs using Parafilm-based thermoplastic materials to adhere the flexible substrate to a rigid glass, achieving smooth, high-quality perovskite films. Consequently, solar cells achieve power conversion efficiency of over 18 % under 1 sun illumination. Furthermore, the stability of f-PSC under different bending conditions (convex/concave under 8 mm bending radius) over time is also investigated. It is found that prolonged convex bending for seven days reduces the performance by 47 %, while it is only 13 % for concave bending. The greater decline in photovoltaic performance during prolonged convex bending is ascribed to the line cracks on the perovskite layer and reduced ITO layer conductivity.