Aggregation-Induced Radical of Donor-Acceptor Organic Semiconductors

Abstract

<p></p><p>Narrow bandgap donor-acceptor organic semiconductors are generally considered to show closed-shell singlet ground state and their radicals are reported as impurities, polarons, charge transfer state monoradical or defects. <a>Herein, we reported the open-shell singlet diradical electronic ground state of two diketopyrrolopyrrole-based compounds Flu-TDPP and DTP-TDPP</a> via the combination of variable temperature NMR, variable temperature electron spin spectroscopy (ESR), superconducting quantum interference device magnetometry, and theoretical calculations. It is observed that the quinoid-diradical character is significantly enhanced in aggregation state because of the limitation of intramolecular rotation. Consequently, we propose a mechanism of aggregation-induced radical to understand the driving force of the open-shell diradical formation of DTP-TDPP based on the ESR spectroscopy test in different proportions of mixed solvents. Our results demonstrate the thermally-excited triplet state for donor-acceptor organic semiconductors, providing a novel view to comprehend the intrinsic chemical structure of donor-acceptor organic semiconductors, as well as the potential electronic transition process between ground state and excited state.<br></p><br><p></p>

Air Stable Chalcogen-Doped Rubicenes with Diradical Character

“…The existence of a weak long tail is in accordance with the previous diradical species. 5,[27][28][29][30][31] In addition, the absorption peaks of O-rubicene are slightly bathochromically shifted to those of S-rubicene, while blue shifted to those of Se-rubicene, which agree well with the B3LYP/6-31G(d,p)-calculated electronic transitions for O-, S-, and Se-rubicenes (Fig. S10).…”

“…This phenomenon indicates that the materials with strong radical properties have more channels for nonradiative transition, resulting in weak luminescence. 29,[32][33] Since diradical compounds usually present Page 7 of 17 CCS Chemistry redox amphoterism characteristics, 25 CV was employed to investigate their electrochemical properties (Fig. 3b).…”