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Updated: Jul 18, 2026

Excitonic Hamiltonians for Calculating Optical Absorption Spectra and Optoelectronic Properties of Molecular Aggregates and Solids
Published on: May 27, 2020
Aggregates of quadrupolar dyes: giant two-photon absorption from biexciton states
Gabriele D'Avino1, Francesca Terenziani, Anna Painelli
1Dipartimento di Chimica GIAF & INSTM UdR di Parma, Università di Parma, Parco Area delle Scienze 17/a, 43100 Parma, Italy.
Abstract:
A model for aggregates of quadrupolar (DAD or ADA) molecules is presented that relaxes the dipolar approximation for intermolecular electrostatic interactions. New effects, including the appearance of bound biexcitons in clusters of nonpolar molecules, are predicted with interesting and unforeseen consequences on the material properties. Specifically, we show that the large two-photon absorption cross-section, typical of quadrupolar chromophores, can be further amplified by orders of magnitude as a result of aggregation.
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