Regulating Electron-Phonon Coupling by Solid Additive for Efficient Organic Solar Cells.

Abstract

Strong electron-phonon couplingcan hinder excitontransport andinduce undesirable non-radiative recombination, resulting in a shortened exciton diffusion distance and constrainedexciton dissociation in organic solar cells (OSCs). Therefore, suppressingelectron-phonon coupling is crucially important for achieve high-performanceOSCs. Here, we employ the solid additive to regulating electron-phonon coupling in OSCs. The planar configuration of SA1 confers a significant advantage in suppressing lattice vibrations in the active layers, reducingthe scattering of excitons by phonons caused by lattice vibrations. Consequently, a slow but sustained hole transfer process is identified in the SA1-assisted film, indicating an enhancement in hole transfer efficiency.Prolongedexciton diffusion length and exciton lifetime are achieved in theblend film processed with SA1, attributed to a low non-radiative recombination rateand low energetic disorderfor charge carrier transport. As a result,a highefficiencyof20% was achieved for ternary device with a remarkable short-circuit current. This work highlights the important role of suppressing electron-phonon coupling in improving the photovoltaic performance of OSCs.