WEB Computational Design of Novel Organic SemiconductorsThursday (24.09.2020) 12:05 - 12:20 M: Modelling and Simulation 1 Part of:
Small-molecule organic semiconductors are used in a wide spectrum of applications, ranging from organic light emitting diodes to organic photovoltaics. A number of factors determine mobility, such as molecular packing, electronic structure, dipole moment and polarizability. Presently, quantitative ab-initio models to assess the influence of these molecule-dependent properties, including the influence of dopants, are lacking. Here, we present a multi-scale model, which provides an accurate prediction of experimental data over ten orders of magnitude in mobility, and allows for the decomposition of the carrier mobility into molecule-specific quantities. The model consists of a multi-step procedure, incorporating single molecule parameterization, generation of atomistic morphologies, DFT based electronic structure calculations yielding site energies, energy disorder, electronic couplings and reorganization energies. These parameters are used in an analytic model to compute the charge carrier mobility of the amorphous materials. We also provide molecule-specific quantitative measures how two single molecule properties, the dependence of the orbital energy on conformation and the dipole induced polarization determine mobility for hole-transport materials. On the basis of this methodology we are able to computationally predict novel pure ETL materials with three orders of magnitude higher mobility than their precursors [and elucidate the molecular mechanism of doping these materials with kinetic Monte-Carlo simulations. The availability of first-principles based models to compute key performance characteristics of organic semiconductors may enable in-silico screening of numerous chemical compounds for the development of highly efficient opto-electronic devices.