A Theoretical Investigation Of The Molecular And Electronic Structure,Carrier Transfer And Intramolecular Through-space Interaction On Pyrene-fluorene Derivatives: A DFT Study

Due to its application in the fields of organic light-emitting diodes(OLEDs),organic field effect transistors(OFETs),organic photovoltaic cells(OPVs),pyrene-fluorene derivatives organic semiconductors(OSCs)recently has received extensive attention from industrial and the scientific community.To reveal the electronic structures,intramolecular interaction,and charge transfer properties relationships of the pyrene-fluorene derivatives materials,an systematically theorical investigation was elaborated.1)At the beginning,from the physical model analysis,this report proofed that the concept of p-type or n-type is not flawless because there is no doping in these OSCs.Then the Marcus theory and first-principles were employed to calculate the intrinsic transfer mobility of these materials including reorganization energies(?)and the transfer integral(V).Research results showed that the studied pyrene-fluorene materials all possessed intrinsic bipolar transfer characteristics.In addition,it is also showed that the electron-rich group is not necessary to improve hole transfer,and that the electron-withdrawing group is also not necessary to improve electron transfer.2)The geometric and electronic structures in the ground-state and excited-state were studied with density functional theory(DFT)emphasis on the highest occupied molecular orbitals(HOMOs),the lowest unoccupied molecular orbitals(LUMOs),energy gaps(Eg),as well as some other electronic properties including ionization potentials(IPs),electron affnities(EAs),and absorption spectra.And the weak interaction method was used to analyze and discuss,and a series of meaningful research results were obtained.3)The molecular were divided into several fragments for the quantitative exploration of the intramolecular through-space interaction.The electron cloud density of different orbits was analyzed,There was a special intramolecular spatial interaction(?-? superconjugation effect)between two isolated conjugated groups,the mechanism of ?-? superconjugation effect and the influence of different molecular structure on intramolecular interaction and electron excitation transition are investigated quantitatively.