Abstract
The structural, optoelectronic, and charge transport properties of dimethyl 2,3-bis((4-(bis(4-methoxyphenyl)amino)phenyl)ethynyl)fumarate (parent compound; E-1) and its acid-induced double lactonization Pechmann dyes, i.e., (E)-5,5′-bis(4-(bis(4-methoxyphenyl)amino)phenyl)-2H,2′H-[3,3′ bifuranylidene]-2,2′-dione (P55), and 3,7-bis(4-(bis(4-methoxyphenyl)amino)phenyl)pyrano[4,3-c]pyran-1,5-dione (P66) were investigated by DFT and TD-DFT calculations for potential use as efficient materials for organic light-emitting diodes (OLEDs). The charge transfer behaviour of these dyes has also been explored by shedding light on the frontier molecular orbitals, vertical ionization potential, reorganization energy, excitation energies, transfer integrals and intrinsic mobility for holes and electrons. The experimental absorption and fluorescence spectra were successfully reproduced by TD-BMK/6-31+G(d,p) level with the conductor-like polarizable continuum model (CPCM) in toluene. Additionally, calculated hole intrinsic mobility of P66 was observed greater than the electron one revealing this compound as p-type material that is rational to experimental data. Moreover, charge transfer nature (p-type or n-type) of E-1 and P55 has been probed on the bases of reorganization energy, transfer integrals and intrinsic mobility which showed that both dyes would be better p-type materials.