Effects of dipole alignment and channel interference on two-photon absorption cross sections of two-dimensional charge-transfer systems

The relationship between two-photon absorption cross sections and the architecture of donor–acceptor substitutions in two-dimensional charge-transfer cumulene-containing aromatic molecules is analyzed. It is shown that a molecular design strategy proposed for one-dimensional charge-transfer molecules must be considerably altered for two-dimensional systems. It is found that the maximal two-photon cross section of such two-dimensional systems can often be well described by a four state model. The importance of the alignment of the transition dipole moments and of channel interference on the two-photon absorption cross sections is emphasized.