Search

Optimization of the electronic properties of crystalline organic semiconductors is important for the evolution of organic optoelectronic devices. One method of tuning the electronic properties is by applying external pressure to semiconducting molecular crystals. A recent dispersion-inclusive density functional theory (DFT) investigation regarding the effect of pressure up to 20 GPa on herringbone polycyclic aromatic hydrocarbons (PAHs) has revealed anomalous pressure dependence of the electronic properties of six systems [J. Phys. Chem. C 122, 23828 (2018)]. Here, we use intermolecular electronic coupling values (H ab), calculated by fragment orbital DFT (FO-DFT) to elucidate the pressure dependence of the electronic properties. We show that discontinuities in the pressure dependence of the band structures are correlated with pressure-dependent discontinuities in the electronic couplings of certain molecular dimers. H ab is shown to be a useful descriptor for gaining insight into the pressure dependence of the electronic properties of crystalline organic semiconductors. [ABSTRACT FROM AUTHOR]

[Display omitted] Organic molecular crystals have shown promise in optoelectronic application due to their potential for exhibiting low excitation energies and high charge carrier mobilities. In order to uncover physicochemical trends that will enable optimization of the electronic properties of these materials, high-throughput dispersion-inclusive density functional theory (DFT + vdW) and fragment-orbital density functional theory (FO-DFT) was used to calculate the electronic properties of 831 single-component organic molecular crystals (OMCs) comprised of C, H, O, and/or N atoms. The resulting data was analyzed using structure-dependent property distributions, Pearson correlation coefficient matrices, Euclidean distances, T-tests, and P-values. It is shown that the atomic species, crystalline space group, and molecular topology control the optical band gap (E g opt ) value, the dispersion of the HOMO and LUMO derived bands, the intermolecular electronic coupling, and the difference between the molecular HOMO-LUMO gap value and crystalline band gap value. Detailed statistical treatment of qualitative and quantitative descriptors shows some new and many expected structure–property relationships. The structure–property data has been organized in the free access Organic Molecular Crystal Properties Database (OMCPD) available at www.organiccrystalbandgaps.org. [ABSTRACT FROM AUTHOR]