Experimental and theoretical studies of absorption and photoluminescence excitation spectra of poly(p-phenylene vinylene)

In this paper, we present the experimental absorption spectra and photoluminescence excitation spectra of poly(p-phenylene vinylene) (PPV). We also present the theoretically calculated absorption and photoluminescence spectra of PPV. The singlet-to-singlet transition energies and moments calculated from the intermediate neglect of differential overlap with the spectroscopic parametrization (INDO/S) semi-empirical method were used to analyze the absorption spectra. The symmetrical vibrational modes calculated from the abinitio method were used to obtain the vibronic features in the spectra of PPV. It is demonstrated that the inhomogeneity observed in the absorption spectra of PPV can be modeled by summing up the absorption of PPV oligomers with different chain lengths. The difference between absorption and photoluminescence excitation spectra is explained.