Alkoxy substitution on asymmetric conjugated molecule enables high-efficiency ternary organic solar cells

Alkoxy substitution on asymmetric conjugated molecule enables high-efficiency ternary organic solar cells
Chemical structures of TB-S, TB-S1, TB-S1-O, and J-V curves of their ternary organic solar cells. Credit: NIMTE

A research group led by Prof. Ge Ziyi at the Ningbo Institute of Materials Technology and Engineering (NIMTE) of the Chinese Academy of Sciences (CAS) has developed an alkoxy-substituted asymmetric conjugated molecule and doped it into the PM6:BTP-eC9-based binary organic solar cells (OSCs) as a third component, resulting in high-efficiency ternary OSCs with a power conversion efficiency (PCE) of over 18.1%.

This work was published in ACS Energy Letters.

OSCs have attracted a lot of attention in the clean solar energy field because of their solution processability, transparency, portability, and flexibility. The ternary strategy is widely recognized as a facile and efficient way to improve OSCs performance.

However, to date, the "structure-performance" correlation of ternary device has rarely been thoroughly and systematically elucidated. Therefore, there is an urgent need to uncover the correlation between , active layer and photovoltaic performance to provide effective strategies for achieving high-performance OSCs.

To address this issue, the researchers synthesized three asymmetric skeleton non-fullerene acceptors, i.e., TB-S, TB-S1, and TB-S1-O, and employed them as the third component in the host binary system of PM6:BTP-eC9, respectively.

Benefiting from the additional noncovalent conformation lock, the alkoxy-substituted TB-S1-O possessed a wide band gap, stable planar conformation, high surface energy, excellent compatibility with the host materials, and a large ordered stacking domain, which shows superior performances than TB-S, TB-S1.

Notably, the PM6:BTP-eC9:TB-S1-O ternary film possesses an ideal interpenetrating network, contributing to a reduction in nonradiative voltage loss and an enhancement in charge transport. Consequently, when the researchers blended TB-S1-O into the PM6:BTP-eC9 system, a significant increase of PCE from 17.36% of binary film to 18.14% of ternary film was demonstrated.

Due to the inferior morphology, the devices based on PM6:BTP-eC9:TB-S and PM6:BTP-eC9:TB-S1 show a remarkably lower PCE (i.e., 16.16% and 16.18%, respectively), in comparison with the PM6:BTP-eC9:TB-S1-O based ternary device.

This work demonstrates that asymmetric skeleton with alkoxy-substitution is an efficient strategy to construct the third component for high-performance ternary OSCs.

More information: Lin Xie et al, Alkoxy Substitution on Asymmetric Conjugated Molecule Enabling over 18% Efficiency in Ternary Organic Solar Cells by Reducing Nonradiative Voltage Loss, ACS Energy Letters (2022). DOI: 10.1021/acsenergylett.2c02201

Journal information: ACS Energy Letters
Citation: Alkoxy substitution on asymmetric conjugated molecule enables high-efficiency ternary organic solar cells (2022, December 8) retrieved 15 June 2024 from
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