Are Coarse-Grained Structures as Good as Atomistic Ones for Calculating the Electronic Properties of Organic Semiconductors?

The quality of amorphous molecular morphologies obtained with a recently introduced coarse-grained model, representing molecules in terms of connected anisotropic beads (Phys. Chem. Chem. Phys. 2019, 21, 26195), is benchmarked against reference atomistic data. Typical small-molecule organic semiconductors in their pristine and doped forms are chosen as a challenging and technologically relevant case study for our comparison, which includes both structural features and the resulting electronic properties, such as charge carrier energy levels, energetic disorder, and intermolecular charge transfer couplings. Our analysis shows that our accurate coarse-grained model leads to molecular glasses that are very similar to native atomistic samples, with the discrepancy being further reduced upon back-mapping. The electronic properties computed for back-mapped morphologies are almost indistinguishable from the atomistic reference, especially for multibranched poly(hetero)cyclic hydrocarbons usually employed as organic semiconductors. This study provides a proof of principle for highly accurate large-scale simulations of complex molecular systems at a reduced computational cost.

Automated summary

The quality of amorphous molecular morphologies obtained with a new coarse-grained model is compared with reference atomistic data. The study focuses on small-molecule organic semiconductors in their pristine and doped forms, analyzing their structural features and electronic properties. The results demonstrate that the accurate coarse-grained model produces molecular glasses that are highly similar to atomistic samples, with even better agreement after back-mapping. The electronic properties of the back-mapped morphologies are almost indistinguishable from the atomistic reference, supporting the feasibility of large-scale simulations of complex molecular systems at a reduced computational cost.