(337l) Advancing Organic Photovoltaic Performance through Tight-Binding Modeling of Exciton and Frontier Orbitals in Conjugated Molecules and Polymers.

Conjugated molecules and polymers serve as promising materials for OPV cells due to their tunable energy levels and ease of fabrication. The performance of OPV cells crucially depends on the efficient generation of free charge carriers through the dissociation of excitons, which are electron-hole pairs formed upon photon absorption. To improve our understanding of exciton dynamics and develop accurate predictions of their behavior on various molecular structures, we extend the tight-binding model to investigate exciton characteristics in homo-oligomers, alternating co-oligomers, and a non-fullerene acceptor - IDTBR.

In this research, we propose a novel parameterization approach for our tight-binding model by utilizing DFT energies of neutral, anion, cation, and excited states of constituent moieties. This enables us to establish a comprehensive description of exciton behavior, including singlet excitations and optical gaps, for oligomers of varying lengths. We carefully validate our tight-binding model's predictions against time-dependent DFT and spectroscopic results, ensuring the reliability and accuracy of our methodology.

A significant challenge arises when dealing with molecules like IDTBR, which feature two ends where excitons can reside, leading to broken symmetry in the product wavefunction exciton. However, our tight-binding model overcomes this limitation by introducing full correlation between the electron and hole, thus enabling the exciton to explore both ends of the molecule. This enhanced understanding of exciton dynamics on complex molecular structures opens up new avenues for improving OPV performance.

Our research seeks to contribute significantly to the advancement of organic photovoltaics by shedding light on exciton behavior in conjugated materials. The insights gained from our modeling approach can be leveraged to design efficient OPV devices, with the potential to drive sustainable energy generation and mitigate environmental challenges. We look forward to engaging in discussions with peers and industry professionals to explore the practical applications of our research and pave the way for a greener and more sustainable future.