Calculation of electron affinity, ionization potential, transport gap, optical band gap and exciton binding energy of organic solids using 'solvation' model and DFT

Abstract

Electron affinity of organic molecules in solids is calculated using density functional theory (DFT) and 'solvation' correction using polarizable continuum model. Computed values for 13 molecules show excellent correlation with experimental values obtained from inverse photoemission spectroscopy. The same method was used to calculate ionization potential and transport gap of the 13 organic molecules in solid state. Optical band gap was calculated for the 13 molecules using time-dependent DFT and polarizable continuum model, which in turn was used to calculate exciton binding energy of the molecules in solid state. Calculated and experimental values show good agreement that it is possible to determine the electron affinity, ionization potential, transport gap and optical band gap of organic molecules in solid state using molecular structure as the only input required for the calculation.