An Electronic Structure Approach to Understand Charge Transfer & Transport in Organic Semiconducting Materials

Effective design of optoelectronic devices requires understanding of the role of the molecular environment. However, widely used forms of DFT and TDDFT fail to accurately describe the frontier orbital gap and charge transfer states of such molecular systems in the condensed phase. Recently we implemented a novel approach combining screened RSH (SRSH) with polarized continuum model (PCM), where long range electrostatic interactions are consistently screened by a 1/e factor (e is the solid-state dielectric constant). Using this new approach, we achieved a highly efficient quantum chemical procedure to obtain condensed phase IP and EA based on single molecule calculations and the correct charge transfer energies of a complex system.
Using this approach, we address molecular conductance where DFT has an established tendency to overestimate the conductance. Here, we develop the approach to address non-equilibrium conditions by using RSH functionals within NEGF formulation to study conductance. We then develop the approach to study NDR based on (phenylene ethynylene) derivatives
We compare the RSH-NEGF results with alternative DFT-NEGF approaches to highlight the importance of using an approach based on physically significant frontier orbitals.