In Less Than a Week, Nankai University’s Yongsheng Chen Publishes Another Paper in EES: 19.42% Efficiency for Binary Systems—Atomically Asymmetric Molecular Design Featuring a Y-Shaped Acceptor Central Unit!
Release Date:
2025-04-09 17:22
Source:
The central unit plays a crucial role in Y-shaped acceptor-based organic solar cells (OSCs). However, acceptors featuring an asymmetric central unit are rare, and their structural characteristics as well as their interactions with the donor remain poorly understood.
Based on this, Chen Yongsheng, Wan Xiangjian, and others from Nankai University A atomic-level asymmetric molecular design strategy was proposed to develop and synthesize two asymmetric acceptors, CH-Bzq and CH-Bzq-Br, as well as a symmetric control acceptor, CH-PHE. Both theoretical calculations and experimental results demonstrate that subtle modifications at the atomic level in the chemical structure effectively tune the molecular dipole moment, packing behavior, and active-layer morphology, ultimately influencing device performance. Notably, owing to favorable phase separation, enhanced charge-carrier dynamics, and superior morphological features, A binary device based on PM6:CH-Bzq-Br achieved an impressive power conversion efficiency (PCE) of 19.42%. Notably, when processed using the green solvent o-xylene, the module delivered an outstanding PCE of 16.08%. Our work highlights the tremendous potential of atomically precise asymmetric molecular design in fine-tuning the nanoscale morphology of the active layer, a critical factor for the development of high-performance organic solar cells. This paper was recently published in the journal under the title “Fine-tuning Central Extended Unit Symmetry via An Atom-Level Asymmetric Molecular Design Enables Efficient Binary Organic Solar Cells.” E Energy & Environmental Science Up.
In summary, the authors propose a novel atomically precise asymmetric molecular design strategy for the design and synthesis of two asymmetric acceptors, CH-Bzq and CH-Bzq-Br. Compared with the reference molecule CH-PHE, even minor modifications in the asymmetry of the central core can lead to substantial changes in molecular packing behavior, donor–acceptor interactions, and active-layer morphology, thereby influencing charge-carrier dynamics and overall device performance. Consequently, owing to the enhanced charge-carrier dynamics and superior active-layer morphology, The PM6:CH-Bzq-Br-based binary OSC achieved a high PCE of 19.42%. This represents one of the highest PCE values reported to date for asymmetric acceptor-based binary systems. It is worth noting that when using When used as a processing solvent, the green solvent o-xy achieved an impressive power conversion efficiency (PCE) of 16.08% in a 13.5 cm² module, underscoring the scalability and practicality of our approach. This work not only introduces an effective molecular design strategy for constructing high-performance acceptors, but also paves a promising path for advancing the development of green-solvent–processed organic solar cells. This strategy is expected to play a pivotal role in further enhancing the performance and commercial viability of organic photovoltaics in the future.
Device Fabrication
Device Structure ：
Glass/ITO/PEDOT:PSS/PM6:CH-BzqBr/PNDIT-F3N/Ag
1. Wash the ITO glass thoroughly, then perform plasma cleaning for 15 minutes. At a substrate temperature of approximately 70°C, blade-coat a PEDOT:PSS layer onto the ITO substrate, maintaining a gap of 200 μm between the substrate and the blade, followed by thermal annealing at 150°C for 20 minutes.
2. Dissolve the active-layer solution (D:a = 1:1.2, 9 mg mL⁻¹:10.8 mg mL⁻¹) in o-xylene. Perform spin coating at a substrate temperature of 60°C, a spin speed of 10 mm s⁻¹, and a gap of 300 μm between the substrate and the blade. Transfer the substrate to a nitrogen-purged glove box and anneal at 100°C for 5 minutes.
3. Deposit the PNDITF3N layer via spin coating.
4. The P2 pattern is mechanically scribed using plastic tweezers. Subsequently, a 150-nm-thick Ag film is deposited via mask-assisted thermal evaporation at a pressure of 3 × 10⁻⁴ Pa to form the P3 line.
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