Charge transport and optical properties of cross-conjugated organic molecules: A theoretical study

The structure, charge transport and optical properties of two-dimensional cruciform molecules 1,4-distyryl-2,5-bis(arylethynyl)benzenes, 1,4-distyryl-2,5-bis(arylethynyl)pyridines and 1,4-bis(ethylenediyl)dipyridine-2,5-bis(benzene) have been studied using density functional theory methods. The effective charge transfer integral and site energy corresponding to hole and electron transports in the above molecules were calculated directly from the matrix elements of Kohn–Sham Hamiltonian. The charge carrier mobility on the cruciform molecules was calculated using Monte Carlo simulation based on the Marcus rate theory and the results show that these cruciform molecules are the p-type organic semiconductors. The excited state calculations were performed using the time-dependent density functional theory method in gas phase, hexane and dichloromethane mediums. The trifluoromethyl substituted 1,4-distyryl-2,5-bis(arylethynyl)benzenes molecule possesses the maximum absorption and emission wavelength of 443 and 504 nm, respectively in dichloromethane medium.