Abstract
Organic semiconductors (OSC) are key components in applications such as organic photovoltaics, organic sensors, transistors and organic light emitting diodes (OLED). OSC devices, especially OLEDs, often consist of multiple layers comprising one or more species of organic molecules. The unique properties of each molecular species and their interaction determine charge transport in OSCs—a key factor for device performance. The small charge carrier mobility of OSCs compared to inorganic semiconductors remains a major limitation of OSC device performance. Virtual design can support experimental R&D towards accelerated R&D of OSC compounds with improved charge transport. Here we benchmark a de novo multiscale workflow to compute the charge carrier mobility solely on the basis of the molecular structure: We generate virtual models of OSC thin films with atomistic resolution, compute the electronic structure of molecules in the thin films using a quantum embedding procedure and simulate charge transport with kinetic Monte-Carlo protocol. We show that for 15 common amorphous OSC the computed zero-field and field-dependent mobility are in good agreement with experimental data, proving this approach to be an effective virtual design tool for OSC materials and devices.
Highlights
The discovery of electroluminescence in organic semiconductors (OSC) by Tang and VanSlyke (1987) triggered an intense research in OSC, leading to their use in a wide range of very thin and potentially printable applications, such as organic solar cells (OPV) (Baran et al, 2018) and organic field-effect transistors (OFET) (Wang et al, 2018) and their common use in organic light emitting diodes (OLEDs) (Fröbel et al, 2018)
The mobility of BPBD was fitted to the emission response from a bilayer TPD–BPBD stack, the mobility of TPDI was fitted to the SCLC
Low charge carrier mobility in OSC materials limits the potential of OSC devices including OLEDs
Summary
The discovery of electroluminescence in organic semiconductors (OSC) by Tang and VanSlyke (1987) triggered an intense research in OSC, leading to their use in a wide range of very thin and potentially printable applications, such as organic solar cells (OPV) (Baran et al, 2018) and organic field-effect transistors (OFET) (Wang et al, 2018) and their common use in organic light emitting diodes (OLEDs) (Fröbel et al, 2018). Over the past 3 decades, OLEDs have evolved significantly from the crude two-layer material used by Tang and VanSlyke into intricate multilayer thin-film devices and are commonly used in displays (Fröbel et al, 2018) and lighting applications (Tsujimura, 2017). Each of these layers consist of one or multiple species of molecules, forming thin amorphous films. In the past 3 decades, intense research into developing materials with improved properties, including increased mobility. A further increase of the accuracy could boost virtual design, enabling researchers to focus experimental efforts in the material development process to promising candidates identified in computer simulations (Friederich et al, 2017)
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