Affiliation:
1. Department of Chemistry College of Humanities and Sciences Nihon University Sakurajosui 3–25-40, Setagaya-ku Tokyo 156-8550 Japan
2. Department of Chemistry Faculty of Science Tokyo University of Science Kagurazaka 1–3, Shinjuku-ku Tokyo 162-8601 Japan
Abstract
AbstractThe development of electron transport and n‐type materials is still largely dominated by a limited number of organic semiconductors, with fullerenes at the forefront. In contrast, substantial progress has been made in developing hole transport and p‐type materials. Therefore, expanding the range of electron acceptors, making them solution‐processable, and elucidating their structural arrangement by X‐ray crystallography is essential. We synthesised 2,2’‐bi‐(5,6,11,12‐tetraazanaphthacene) (bi‐TANC) and its triptycene end‐capped derivative, 2,2′‐bi(8,13‐dihydro‐8,13‐[1,2]benzenonaphtho‐5,6,15,16‐tetraazanaphthacene) (bi‐TpTANC), as electron acceptors. Bi‐TANC exhibits a herringbone‐like crystal packing with intermolecular π–π overlap, which is observed in typical organic n‐type semiconductors. However, it showed poor solubility, similar to larger acenes. In contrast, bi‐TpTANC exhibited favourable solubility, and its electrochemistry in solution was investigated. In the cyclic voltammogram of bi‐TpTANC, reversible redox waves corresponding to 3‐step/4‐electron transfer were observed at −0.795 V (1e−), −0.927 V (1e−), and −1.44 V (2e−) as half‐wave potentials. The redox wave associated with the two‐electron transfer on the negative low‐potential side indicates the presence of through‐bond charge delocalisation in the monoanionic state. Furthermore, the LUMO level of bi‐TpTANC is −4.1 eV, which indicates its potential as a promising air‐stable n‐type material.