Universality and Specificity of Ambipolar Organic Materials: A Scope Combined Micro-area Photocurrent Spectroscopy and Raman Imaging in Y6

Ambipolar organic materials exhibit extremely complex operating mechanisms that urgently require theoretical refinement and supplementation. This work combined micro-area photocurrent and Raman imaging techniques to explore the in situ carrier dynamics. P3HT/Y6 is employed as donor/acceptor (D/A) materials for the active layer of organic field-effect transistors (OFETs), where the devices exhibit distinct ambipolar transport characteristics. The observed basic spatial distribution of electric potential and energy band bending coincide well with the classic theories of semiconductor device physics, which testify the reliability of the experimental method. For more details, some unique experimental phenomena are observed in organic materials, including bidirectional positive response, inversion of potential distribution in the linear region, and disappearance of the saturation pinch-off point. The presence of spatial charge in organic conjugated structures is an important reason for the special phenomena; the introduction of Y6 has enabled us to observe many changes that were previously difficult to observe, which, on another aspect, helps reveal the reasons for the excellent performance of Y6. These results would help to gain a deeper understanding of organic semiconductor physics and optimize organic optoelectronic device performance.