The electron transfer rate of large TPA based compounds: a joint theoretical and electrochemical approach

Abstract

A series of triphenylamine (TPA) based compounds is investigated by means of density functional theory and cyclic voltammetry. Using the Nicholson’s formalism, the measured ΔE_p are correlated with B3LYP/6-31G* calculated reorganisation energies (λ), elucidating the trend followed by the electron transfer rate of these compounds. Besides the direct dependency upon the dimension of the cationic fragment contributing to the hole stabilisation, the λs are tuned by the symmetry local to the TPA units, as evidenced by the structural relaxation of the cations. MDTAB shows the interesting combination of low ionisation potential (IP) and low λ. This can make this compound interesting for practical applications in organic light emitting diode (OLEDs) devices, due to the direct correlation of the IP and λ with the hole transfer efficiency to the anode, along with the hole mobility.