Top-Gate Field-Effect Transistor as a Testbed for Evaluating the Photostability of Organic Photovoltaic Polymers

Light-induced performance degradation in organic solar cells (OSCs) is a major impediment to their commercialization. As the photostability of OSCs strongly depends on the material's properties, the most effective solution for this concern is to develop a photostable material. However, the wide variety of causes of photo-instability in a standard multilayered OSC structure complicates the evaluation of photostability of newly developed materials. To address this challenge, a top-gate field-effect transistor (FET) as a testbed for evaluating the photostability of OSC materials is proposed. This device test platform minimizes the internal and external origins of photo-instability by employing a fluoropolymer gate dielectric. The photostability of an OSC material incorporated in this FET testbed can be evaluated by monitoring light-induced mobility degradation. Two types of common donor polymers with similar chemical structures and crystallinity are employed as test materials, and their photostability is evaluated. The test results correspond to the photostability measurements conducted in the standard OSC structure, validating the proposed FET testbed. The proposed FET testbed enables rapid evaluation of the photostability of a newly developed OSC material, thereby providing timely feedback to material scientists. This boosts the development of photostable OSC materials.