Bis(arylene-ethynylene)-s-tetrazines: A Promising Family of n-Type Organic Semiconductors?

We theoretically describe in this work the n-type semiconducting behavior of a set of bis(arylene-ethynylene)-s-tetrazines ((ArCC)2Tz), by comparing their electronic properties with those of their parent diaryl-s-tetrazines (Ar2Tz) after the introduction of ethynylene bridges. The significantly reduced internal reorganization energy for electron transfer is ascribed to an extended delocalization of the LUMO for (ArCC)2Tz as opposite to that for Ar2Tz, which was described mostly localized on the s-tetrazine ring. The largest electronic coupling and the corresponding electron transfer rates found for bis(phenyl-ethynylene)-s-tetrazine, as well as for some halogenated derivatives, are comparable to those reported for the best performing n-type organic semiconductor materials such as diimides and perylenes. The theoretical mobilities for the studied compounds turn out to be in the range 0.3–1.3 cm2 V–1 s–1, close to values experimentally determined for common n-type organic semiconductors used in real devices. In addition, ohmic contacts can be expected when these compounds are coupled to metallic cathodes such as Na, Ca, and Sm. For these reasons, the future application of semiconducting bis(phenyl-ethynylene)-s-tetrazine and its fluorinated and brominated derivatives in optoelectronic devices is envisioned.

The research in Bordeaux has been funded by the French National Grant ANR-10-LABX-0042-AMADEus, managed by the National Research Agency under the initiative of excellence IdEx Bordeaux programme (Reference ANR-10- IDEX-0003-02). The work in Mons was supported by the Programme d’Excellence de la Région Wallonne (OPTI2MAT Project) and the Belgian National Fund for Scientific Research (FNRSFRFC). J.M.G.-R. and M.F.-G. thank the Consejería de Innovación, Junta de Andalucía for their financial support (FQM337 Grant).