Enhanced device performance through optimization of acceptor layer thickness relative to exciton diffusion length and ionization energy offset in bilayer organic solar cells
Huang, Y.; Azeez, A.; Zhao, J.; Zhao, Z.; Dasannagari, M.; Laquai, F.; Kan, Z.; Karuthedath, S. J. Mater. Chem. C 2025, 13, 5911–5919. https://doi.org/10.1039/d4tc05190d
The goal of this study was to enhance the performance of bilayer organic solar cells (b-OSCs) by optimizing the non-fullerene acceptor (NFA) layer thickness relative to exciton diffusion length and adjusting the ionization energy (IE) offset between donor and acceptor materials.
Key findings revealed that matching the COi8DFIC acceptor layer thickness (~40 nm) to its exciton diffusion length (39.4 nm) and using an optimal IE offset (~0.55 eV) with the donor PTB7-Th significantly boosted device efficiency. This dual optimization achieved a power conversion efficiency (PCE) of 11.42%, improved short-circuit current, faster carrier extraction (~690 ns), and reduced bimolecular recombination losses. Deviations from this optimized thickness or IE offset resulted in notable performance drops.
Fluxim’s Paios platform, coupled with Setfos, was critical for characterizing transient photocurrent (TPC), transient photovoltage (TPV), and photo-CELIV measurements. These precise, reproducible electro-optical characterizations provided deep insights into charge carrier dynamics, confirming faster charge extraction and lower recombination rates in optimized devices. The use of Paios notably accelerated optimization and validation, underlining the advantage of high-quality, integrated measurement and simulation tools in organic photovoltaics research.
The findings are important because they offer a rational design strategy for high-performance b-OSCs, paving the way for more efficient, scalable organic solar technologies.