Speaker
Description
Non-covalent interactions (NCIs), such as dispersion and induction, play a crucial role in determining the properties of molecular crystals, especially in organic semiconductors (OSCs). Thanks to their customizability and high-value applications, OSCs are seen as promising alternatives to inorganic semiconductors. Unfortunately, their widespread adoption has been hindered by disappointing performance in benchtop experiments. A significant obstacle in improving their performance is the limited understanding of NCIs in OSC crystals, exacerbated by the lack of established benchmarks specific to these systems. While methods for correcting dispersion and other NCIs are well-established for smaller molecules, their applicability to the large, highly conjugated, and often heterocyclic structures typical of OSC molecules remains uncertain. Nevertheless, existing benchmarks suggest that density functional theory (DFT)-based methods provide a balance between computational efficiency and accuracy, particularly when used in tandem with temperature-based adjustments to calculate material properties.
This work evaluates the performance of two DFT-based dispersion correction schemes, DFT-D3 and DFT-D4, in the context of heterocyclic OSC precursors. With the quasi-harmonic approach, we compare these methods by calculating finite-temperature thermodynamic properties of the precursors, including their densities, heat capacities, and sublimation enthalpies. Insights gained from this study will contribute to the development of much-needed benchmarks for OSC crystals and guide the rational design of new OSC materials by elucidating the role of dispersion forces and thermal effects on the energetic landscapes of conjugated molecular motifs prevalent in OSCs.
