Geometric and Electronic Structures of a Hole-Transport Material,TPD, and Related-Materials Studied by DFT Calculations and Solid-State NMR

摘要

The geometric and electronic structures of organic materials in OLEDs are the underlying basis of the devices.However, the materials are in the amorphous states and the detailed analysis has been difficult so far. In this study, weattempt the detailed analysis of a hole-transport material, N,N'-diphenyl-N,N'-di(m-tolyl)benzidine (TPD), by solid-stateNMR measurements. The chemical shifts are found to depend significantly on the molecular structures. The chemicalshifts also reflect the electronic states of TPD. With the help of DFT calculations, the geometric and electronicstructures of TPD are analyzed. The DFT calculations are also carried out for TPD and the related materials, replacing Natoms of N,N,N',N'-tetraphenylbenzidine to P or B. Not only the calculations of reorganization energies for singlemolecules but also those of intermolecular interactions between adjacent two molecules provide us information on theperformances of carrier transports for respective materials.