Theoretical study on the one- and two-photon absorption properties of a series of octupolar oligofluorenes and dipolar analogs

A comparative study of electronic structure, one-photon absorption and two-photon absorption properties of octupolar oligofluorenes and their dipolar counterparts is presented by using AM1 and ZINDO-SOS methods. The conjugation length and molecular dimension importantly affect TPA cross-section values. The maximum TPA cross-section increases in proportion to Nα (α=2.41 and 2.24), where N is the number of fluorene moieties in dipolar molecules and each arm of octupolar analogs.