EFFECT OF SUBSTITUENTS ON THE CHARGE TRANSFER PROPERTIES AND REORGANISATION ENERGIES OF TETRAPHENYL-1,4-PHENYLENEDIAMINE- A DFT COMPUTATIONAL APPROACH

This theoretical study explores the effect of substitution on the electronic properties and reorganisation energy of N,N,N,N-tetraphenyl-1,4-phenylenediamine derivatives (TPD), focussing on selected electron-donating groups (alkyl and alkoxy)substituted diagonally at the meta and para positions.Using computational methods, the energy levels (HOMO and LUMO), energy bandgap, ionisation potential and reorganisation energies were calculated to assess charge transfer properties.While alkyl substituents show minimal band gap variation with chain length, para-alkyl derivatives exhibit reduced reorganisation energy and improved hole mobility, with linear chains outperforming branched ones.For alkoxy derivatives, trends in reorganisation energy are less consistent, but increasing chain length enhances hole mobility and reduces electron mobility.This study emphasises the critical role of substitution patterns and side chain architecture in optimising TPD derivatives for charge transport applications