(332d) Morphology and Charge Transport Predictions across Organic Photovoltaic Components Using Coarse-Grained Molecular Dynamics

Optimizing optical and electronic properties of organic photovoltaic active layers is important for realizing low-cost, high-efficiency solar power. Molecular simulations can guide selection of organic components and processing conditions if sufficiently large length scales and time scales can be accessed. We manage ensembles of multiscale molecular dynamics simulations of polymer electron-donor and both fullerene and non-fullerene electron-acceptor materials, making extensive use of MoSDeF tools signac, foyer, and mBuild. Coarse-grained representations and GPU acceleration are used to access long-time equilibration dynamics. Atomistic representations from the coarse models are used for calculating charge transfer dynamics between chromophores, in service of predicting charge mobility as a proxy for active layer quality. We find simplified coarse-grained representations to reliably predict experimentally-validated morphologies for broad classes of organic components and describe specifics for ITIC, PTB7, BDT-TPD, PCBM, and P3HT. Varying agreement between our predictions of charge mobility and measured experimental values reinforce charge assumptions of charge delocalization that are valid for small-monomer polymers, but which need improvement for large non-fullerene acceptors. The predictive capabilities of coarse-grained models suggest that as these simulations become more routine, adding non-equilibrium and rheological processing effects and improving the speed and accuracy of charge transport calculations will be the next frontiers in organic photovoltaic optimization.