PerspectiveApplied Physics

Tuning organic band structures with Coulomb interactions

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Science  17 Jun 2016:
Vol. 352, Issue 6292, pp. 1395-1396
DOI: 10.1126/science.aaf8937

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Summary

The working principles of semiconductor devices are crucially determined by their band gap—the amount of energy needed to excite immobile charge carriers into ones that conduct current. In many inorganic semiconductors, band gaps can be tuned in a systematic way by alloying or inducing strain in the material. Although devices based on organic semiconductors are already in commercial use, there are few rational approaches for similar “band structure engineering” of these materials. On page 1446 of this issue, Schwarze et al. (1) now demonstrate, using long-range Coulomb interactions, a tuning effect of the band structure for organic semiconductors that are weakly bound by van der Waals forces. This effect, which has been totally neglected in discussions of the electronic states, is rather closely related to universal features of organic molecular crystals (2).