Effect of electron-donating groups on the electrochemical and optical properties of indoline substituents as hole transport materials: A computational study

The effect of electron-donating property of the groups attached to the indoline substituents with two different low-cost cores (tetraazafulvalene and pyrene) as new hole transport materials (HTMs) was studied on their electrochemical and optical behaviors. The calculations were carried out based on the theoretical approaches including density functional theory (DFT), time-dependent density functional theory (TD-DFT), and Marcus theory. Some important parameters, such as hole mobility, solubility and stability, absorption and emission spectra, Stokes shift, and HOMO/LUMO energies and distributions were obtained and discussed. It was found that the HOMO of all the designed structures is distributed more widely than their LUMO. The results showed that the maximum absorption band of the designed HTMs is red shifted as the electron-donating ability increases. It is also predicted that TAF/indoline-OMe and Py/indoline-NH2 with the hole mobility of 2.90 x 10(-3) and 1.51 x 10(-3) cm(2) V-1 s(-1), respectively give higher fill factor and short-circuit current density of the device.