Theoretical investigation of the electronic structure of donor/acceptor substituted phenylene vinylene oligomers

Summary form only given. We investigate the geometric and electronic structure of poly(paraphenylene vinylene) - PPV oligomers substituted by various electron donor and/or acceptor groups. Such PPV derivatives have attracted much interest as active layers in light emitting diode (LED) devices. Geometry optimizations are carried out at the AM1 level whereas the electronic properties are derived from INDO calculations considering a configuration interaction approach. We analyze the influence of the location and nature of the substituents on the highest occupied and lowest unoccupied molecular levels; an increase of the electron affinity with respect to that of PPV can allow the use of more environmentally stable metal electrodes in LED devices, e.g., aluminum electrodes. We simulate the whole UV-visible optical absorption spectra of the substituted oligomers and describe the effects of the donor and acceptor groups on the characteristics of the different peaks.