New layer-by-layer strategy achieves 19.8% efficiency in organic photovoltaics

Shanghai Jiao Tong University Journal Center

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image: 

(a) Chemical structures;

(b) energy levels;

(c) normalized absorption spectra of D18, L8-BO and P66;

(d) schematic architecture of LOPVs

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Credit: Hongyue Tian, Naichao Zheng, Minqi Luo, Zuliang Zhuo, Hang Zhou, Tengfei Han, Byung Hui Lee, Han Young Woo, Qianqian Sun, Cong Zhang, Xiaoling Ma & Fujun Zhang.

Researchers from Beijing Jiaotong University and their collaborators have developed a novel morphology engineering strategy to boost the performance of layer-by-layer organic photovoltaics (LOPVs). By incorporating a trace amount of a high-crystallinity, high-hole-mobility polymer into the acceptor layer, the team successfully achieved a power conversion efficiency (PCE) of 19.81%.

Organic photovoltaics (OPVs) are gaining significant attention as a next-generation clean-energy technology due to their low cost, flexibility, and solution-processability. While LOPVs—constructed by layering donor and acceptor materials—are among the most promising designs, achieving high efficiency has been hampered by the disordered molecular packing of many acceptor materials, which limits the transport of photogenerated holes.

In the study published in ENGINEERING Energy, the researchers introduced a polymer named P66—which features a planar donor-acceptor structure and high hole mobility—into the acceptor layer of LOPVs.

Key Research Highlights:

• Enhanced Efficiency: The optimized LOPVs reached a PCE of 19.81%, a significant improvement over the 18.97% achieved by the control devices.
• Improved Device Parameters: Introducing just 0.005 wt.% P66 into the acceptor layer (L8-BO) improved the short-circuit current density (JSC) from 26.87 to 27.72 mA/cm2 and the fill factor (FF) from 78.61% to 79.39%.
• Efficient Hole-Transport Network: The high-crystallinity P66 facilitates the formation of an efficient hole-transport network, promoting the transport of holes generated from exciton self-dissociation within the acceptor layer.
• Optimized Molecular Packing: GIWAXS measurements confirmed that the incorporation of P66 regulates molecular arrangement, resulting in improved face-on molecular orientation.
• Proven Universality: The team demonstrated that this doping strategy is highly versatile, effectively enhancing the performance of LOPVs using various other acceptor materials, including BTP-eC9, Y6, and BO-4Cl.

"Our results indicate that intentionally incorporating materials with high hole mobility and crystallinity into the acceptor layer is a highly effective strategy for boosting LOPVs performance," the authors noted. By regulating the morphology at a molecular level, this approach provides a robust pathway for the further development of high-efficiency, flexible, and sustainable solar energy devices.

 

Journal: ENGINEERING Energy

Read the full article for free: https://rdcu.be/frN5a

Cite this article: Tian, H., Zheng, N., Luo, M. et al. Over 19.8% efficiency layer-by-layer organic photovoltaics by incorporating a high-mobility crystallinity material into the acceptor layer. ENGINEERING Energy 20, 10802 (2026). https://doi.org/10.1007/s11708-026-1080-2

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Journal

ENGINEERING Energy

DOI

10.1007/s11708-026-1080-2 

Method of Research

News article

Article Title

Over 19.8% efficiency layer-by-layer organic photovoltaics by incorporating a high-mobility crystallinity material into the acceptor layer