Exciton Diffusion in Conjugated Polymers: From Fundamental Understanding to Improvement in Photovoltaic Conversion Efficiency

TLDR

In organic photovoltaics, singlet excitons generated by light absorption must diffuse to donor–acceptor interfaces before deactivation, making exciton diffusion dynamics a critical determinant of device performance. The study reviews recent research and outlines strategies to enhance exciton harvesting at these interfaces in OPVs. It examines exciton diffusion mechanisms and proposes approaches for efficient exciton capture to improve charge generation.

Abstract

Singlet exciton diffusion plays a central role in the photovoltaic conversion in organic photovoltaics (OPVs). Upon light absorption, singlet excitons are promptly generated in organic materials instead of charge carriers because the dielectric constant (εr) is small (∼3–4), which is in sharp contrast to inorganic and perovskite solar cells. In order to convert to charge carriers, excitons need to diffuse into an interface between electron donor and acceptor materials before deactivating to the ground state. Therefore, fundamental understanding of exciton diffusion dynamics is one of the most important issues to further improve OPVs. We highlight recent leading studies in this field and describe several approaches for efficient exciton harvesting at the interface in OPVs.