DFT study on electronic structures and spectra properties of substituent pentacene connected with electron donating and withdrawing groups

The geometric structures of pentacene and fifteen substituent pentacene were optimized at B3LYP/6-31G(d) level by Density Functional Theory(DFT) method. The regularities of substituent effects of the electron-donating group(-OCH3) and the electron-withdrawing group(-CN and -F) on electronic structure and the frontier molecular orbital energies of pentacene were investigated. On the same basis, the electronic absorption spectra of the excited state were calculated by time-dependent density functional theory. The computed results show that the introducing of substituent groups significantly affected the electronic structure, frontier molecular orbital energies and optoelectronic property of pentacene.