The mixing of Frenkel-and charge-transfer excitons in 1D structures: Application to PTCDA and MePTCDI

摘要

The exciton structure of crystalline PTCDA (3,4,9,10-perylenetetracarboxylic dianhydride) and MePTCDI (N-N'-dimethylperylene-3,4,910-dicarboximide) is modeled by a one-dimensional Hamiltonian, which inclues interactions between Frenkel excitons with several vibronic levels and charge transfer excitons. With appropriate fitting parameters, which are verified by quantum chemical calculations, this model can explain the main features of the low temperature absorption spectra. Plarized absorption spectra of MePTCDI show different polarization ratios for the various peaks. This polarizaion behavior is explained by the varying contribution of the CT transition dipole, which has a direction differnet from the Frenkel transition dipole.