Thin Films of Conjugated Chalcogenadiazole: Growth, Structure, and Optical Properties of Substituted Selenadiazoloquinoxaline

Thin films of pi-conjugated organic molecules are of high interest for organic optoelectronics. Due to their strong and tunable absorption spectrum and good charge carrier mobilities, thiadiazolo-heteroacenes are considered to be a prospective class of materials for these applications. Additional chemical modification of these molecules by heavy Se atoms and extending the pi-conjugation hold promise to further tune the optical properties and structural arrangement through the heavy atom effect and secondary interactions. Therefore, understanding the thin film growth behavior as well as the optical properties of such derivatives is crucial for future applications. In this study, thin films of dibenzoselenadiazoloquinoxaline (dbSeQ) were grown under ultra-high vacuum conditions by organic molecular beam deposition on native silicon oxide substrates at different temperatures. Their optical properties, structure, and morphology were examined by optical spectroscopy, time-resolved fluorescence spectroscopy, ellipsometry, time-resolved surface-sensitive X-ray scattering, and microscopy techniques.