Indium Zinc Tin Oxide Bottom Electrode‐Based Flexible Indoor Organic Photovoltaics with Remarkably High Mechanical Stability

Abstract

The demand for flexible indoor organic photovoltaic cells (OPVs) is growing dramatically due to their simple and practical use as a powering aid for various electronic gadgets connected to the Internet of Things. Due to the brittleness of inorganic material‐based transparent bottom electrodes and their incompatibility with flexible organic substrates, it is extremely difficult to limit the influence of mechanical stress on the stability of flexible OPV. In this regard, choosing a mechanically stable and highly conductive transparent conducting oxide (TCO) is crucial. Therefore, flexible OPVs are fabricated onto a flexible (polyimide) substrate coated with mechanically stable TCO indium zinc tin oxide (IZTO). Sheet resistance measurements and observations of scanning electron microscope images of IZTO film after 100 000 bending repetitions (bending radius: 5 mm) confirm the ultrahigh mechanical stability of the TCO. The sheet resistance of flexible IZTO electrode layers is increased by 9%, from 17.42 to 19.12 Ω sq−1. In addition, the impact of a large number of bending repetitions on film transmittance is minimal. The OPV shows ≈69% and ≈20% of its initial power conversion efficiency value after 100 000 bending repetitions for 1000 lx LED illumination and 1 sun conditions, respectively.