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DOE OSTI · 1981355

A Top-Down Strategy to Engineer ActiveLayer Morphology for Highly Efficient and Stable All-Polymer Solar Cells

Fu, Huiting·Peng, Zhengxing·Fan, Qunping·Lin, Francis R.·Qi, Feng·Ran, Yixin·Wu, Ziang·Fan, Baobing·Jiang, Kui·Woo, Han Young·Lu, Guanghao·Ade, Harald·Jen, Alex K.‐Y.
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Abstract

A major challenge hindering the further development of all-polymer solar cells (all-PSCs) employing polymerized small-molecule acceptors is the relatively low fill factor (FF) due to the difficulty in controlling the active-layer morphology. The issues typically arise from oversized phase separation resulting from the thermodynamically unfavorable mixing between two macromolecular species, and disordered molecular orientation/packing of highly anisotropic polymer chains. Herein, a facile top-down controlling strategy to engineer the morphology of all-polymer blends is developed by leveraging the layer-by-layer (LBL) deposition. Optimal intermixing of polymer components can be achieved in the two-step process by tuning the bottom-layer polymer swelling during top-layer deposition. Consequently, both the molecular orientation/packing of the bottom layer and the molecular ordering of the top layer can be optimized with a suitable top-layer processing solvent. A favorable morphology with gradient vertical composition distribution for efficient charge transport and extraction is therefore realized, affording a high all-PSC efficiency of 17.0% with a FF of 76.1%. The derived devices also possess excellent long-term thermal stability and can retain >90% of their initial efficiencies after being annealed at 65 °C for 1300 h. In conclusion, these results validate the distinct advantages of employing an LBL processing protocol to fabricate high-performance all-PSCs.

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14 SOLAR ENERGYall-polymer solar cellsblend morphologychemistrydevice stabilitylayer-by-layer depositionmaterials sciencephysicspower conversion efficiencysciencetechnology

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Fu, Huiting, Peng, Zhengxing, Fan, Qunping, Lin, Francis R., Qi, Feng, Ran, Yixin, Wu, Ziang, Fan, Baobing, Jiang, Kui, Woo, Han Young, Lu, Guanghao, Ade, Harald, Jen, Alex K.‐Y.. 2022-06-24. A Top-Down Strategy to Engineer ActiveLayer Morphology for Highly Efficient and Stable All-Polymer Solar Cells. https://doi.org/10.1002/adma.202202608

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