Improving Energy Transport by Cascade Type Architecture in OPVs

Organic photovoltaic (OPV) devices represent an emerging technology for sustainable solar energy conversion. The cascade architecture, which combines multiple donor and acceptor materials, enables device efficiency improvement through optimization of sublayer lengths and material ordering. We investigated light absorption and exciton diffusion in an OPV donor layer using tetracene, rubrene, 5,6-diphenyl-tetracene, and 5,6-Dy-naphthyl-tetracene. The device is simulated through an integrated workflow combining excited state density functional calculations with the kinetic Monte Carlo method under the Förster resonance energy transfer model, effectively simulating exciton dynamics. Moreover, we propose a model to account for the light irradiation source effect in the cascade ordering. Our results demonstrate that material absorption and emission spectra can effectively infer optimal exciton transport parameters while showing that suboptimal parameter selection in cascade architecture can severely reduce exciton collection efficiency. Depending on the order of materials, the active layer can display collected efficiencies from 6% to 57%. Moreover, the proposed methodology can be extended to other cascade setups, offering a computationally cost-efficient approach for predicting the most effective layer arrangement.