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Resonant Tunneling and the Optical Response of Conjugated Molecules

Y. Verbandt, H. Thienpont, I. Veretennicoff, P. Geerlings, and G. L. J. A . Rikken

Conjugated molecules are promising organic materials for photonic switching applications because of their potentially large nonresonant nonlinear response due to the easy delocalization of the -π electrons along their backbone. In addition, the ability to process these molecules into thin films on various substrates presents a major advantage from a device engineering standpoint. To design new compounds, an accurate estimate of the molecular length at which the optical response saturates is needed. We have shown1, that treating a conjugated molecule as a set of adequately coupled quantum oscillators leads to a strikingly good description of the experimentally observed length dependencies. This model is suitable for the study of the scaling laws, the effect of conformation, and of excited-state enhancement on the optical response.