GEOMETRIC and ELECTRONIC PROPERTIES of OLIGOMERS BASED ON LUORINATED THIOPHENES and 1H-PHOSPHOLES: N- VERSUS P-TYPE MATERIALS

Abstract

A series of oligothiophenes and novel oligophospholes, consisting of fluorinated and perfluoroarene-substituted structures, were investigated by using density functional theory (DFT) method. The study focused on the geometrical structures and electronic properties. The degree of -conjugation in the neutral oligomers was studied by different approaches including analysis of predicted Raman spectra. The character of the charge carrier of the new substituted oligomers, either electron (n-type doping) or hole (p-type doping) transport, was predicted by comparing their properties, including the HOMO and LUMO energies, excitation energies, and reorganization energies, with those of their non-substituted parent oligomers. The DFT results are consistent with the available experimental data on the oligothiophenes for both geometries and conductivity properties. The results strongly suggest that an effective way of designing new materials with n-type conductivity is to introduce electron-withdrawing groups into the oligomer backbone. Interesting results were also obtained for oligomers based on 1H-phospholes, which are predicted to have interesting properties as new semiconductor materials..