Charge transport simulations in conjugated dendrimers

Abstract

We present here a theoretical methodology that exploits quantum mechanical calculations, molecular mechanics calculations, and Monte Carlo simulations to predict the time-of-flight measurement mobilities in films of phenyl-cored conjugated thiophene dendrimers. Our aim is to reveal structure-property relationships in amorphous films of organic pi-conjugated materials. The simulations show that both hole and electron mobilities increase with the size of dendrimer, and that the former is larger than latter in all dendrimers. Internal reorganization energies are inversely correlated with the mobilities. Our simulations also indicate that dendrimers have small density of states for energetic disorder (<60 meV), and both hole and electron mobilities possess weak electric field dependence. We examine the influence of external reorganization energy as well as the possible trap sites on charge transport in these materials.