Suppressing Electron–Phonon Coupling via Solid Additives for High-Performance Organic Solar Cells

Abstract

The strong electron–phonon coupling in organic photovoltaic materials significantly impedes exciton transport and promotes charge recombination, thereby exerting a detrimental effect on the overall performance of organic solar cells (OSCs). Mitigating electron–phonon coupling is therefore essential for developing high-performance OSCs. In this work, we introduce two solid additives, 1-bromo-3-chloronaphthalene (BCN-1) and 1-chloro-3-bromonaphthalene (BCN-2), into the bulk heterojunction active layer to address this fundamental challenge. We demonstrate that BCN-2 effectively suppresses high-frequency lattice vibrations, which minimizes electron–phonon scattering and thereby promotes efficient and long-range exciton diffusion. As a result, the BCN-2 processed devices exhibit prolonged exciton lifetime and superior charge carrier mobility compared to the control devices. These synergistic improvements in photophysical properties such as charge transport, contribute to a remarkable power conversion efficiency of 19.72% in the PM6:L8-BO-based OSCs. This work underscores the suppression of electron–phonon coupling as a critical and general strategy for advancing the performance of organic photovoltaic devices.

Keywords

electron–phonon coupling / exciton lifetime / morphology optimization / organic solar cells / solid additive

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2026 The Author(s). Aggregate published by SCUT, AIEI, and John Wiley & Sons Australia, Ltd.