Charge carrier and optoelectronic properties of phenylimidazo[1,5-a]pyridine-containing small molecules at molecular and solid-state bulk scales

Abstract

Various optoelectronic and charge transfer properties of 3-(1H-indol-3-yl)-1-phenylimidazo[1,5-a]pyridine (Comp 1), 1,3-diphenylimidazo[1,5-a]pyridine (Comp 2), and 3-(Anthracen-9-yl)-1-phenylimidazo[1,5-a]pyridine (Comp 3) have been explored at the molecular and solid state bulk level. The absorption and emission spectra (λabs and λemi) were calculated by time domain B3LYP/6-311G*, CAM-B3LYP/6-311G*, LC-BLYP/6-311G* and PBE0/6-311G* levels. The hybrid functionals B3LYP and PBE0 successfully reproduced experimental λabs and λemi more accurately than the long-range corrected functionals. Effect of indol, phenyl and anthracenyl moieties on various properties of interests has been explored. The indol and phenyl units lead to smaller hole reorganization energies and greater transfer integrals resulting superior hole intrinsic mobility for Comps 1 and 2. The substitution of anthracenyl moiety at phenylimidazo[1,5-a]pyridine core increase the electron affinity and electron transfer integrals while decrease the electron reorganization energy. The n- or p-type charge transfer nature of Comp 3 or Comps 1 and 2 has been explored, respectively. The frontier molecular orbitals, ionization potential, electron affinity, reorganization energy, transfer integral, intrinsic mobility, density of states, dielectric constant, extinction coefficient, refractive indices, reflectivity and conductivity shown that imidazo[1,5-a]pyridine derivatives would be efficient materials to be used in multifunctional organic semiconductor devices.