Achieving 19% Power Conversion Efficiency in Planar-Mixed Heterojunction Organic Solar Cells Using a Pseudosymmetric Electron Acceptor

Wei Gao; Feng Qi; Zhengxing Peng; Francis R Lin; Kui Jiang; Cheng Zhong; Werner Kaminsky; Zhiqiang Guan; Chun-Sing Lee; Tobin J Marks; Harald Ade; Alex K-Y Jen

doi:10.1002/adma.202202089

Achieving 19% Power Conversion Efficiency in Planar-Mixed Heterojunction Organic Solar Cells Using a Pseudosymmetric Electron Acceptor

Adv Mater. 2022 Aug;34(32):e2202089. doi: 10.1002/adma.202202089. Epub 2022 Jul 11.

Authors

Wei Gao^{1

2}, Feng Qi^{2

3}, Zhengxing Peng⁴, Francis R Lin^{2

3}, Kui Jiang^{1

2}, Cheng Zhong⁵, Werner Kaminsky⁶, Zhiqiang Guan³, Chun-Sing Lee^{2

3}, Tobin J Marks⁷, Harald Ade⁴, Alex K-Y Jen^{1

2

3

8}

Affiliations

¹ Department of Materials Science and Engineering, City University of Hong Kong, Kowloon, 999077, Hong Kong.
² Hong Kong Institute for Clean Energy, City University of Hong Kong, Kowloon, 999077, Hong Kong.
³ Department of Chemistry, City University of Hong Kong, Kowloon, 999077, Hong Kong.
⁴ Department of Physics and Organic and Carbon Electronics Laboratories (ORaCEL), North Carolina State University, Raleigh, NC, 27695, USA.
⁵ Department of Chemistry, Hubei Key Lab on Organic and Polymeric Optoelectronic Materials, Wuhan University, Wuhan, 430072, China.
⁶ Department of Chemistry, University of Washington, Seattle, WA, 98195-2120, USA.
⁷ Department of Chemistry and the Materials Research Center, Northwestern University, Evanston, IL, 60208, USA.
⁸ Department of Materials Science and Engineering, University of Washington, Seattle, WA, 98195-2120, USA.

PMID: 35724397
DOI: 10.1002/adma.202202089

Abstract

A record power conversion efficiency (PCE) of over 19% is realized in planar-mixed heterojunction (PMHJ) organic solar cells (OSCs) by adopting the asymmetric selenium substitution strategy in making a pseudosymmetric electron acceptor, BS3TSe-4F. The combined molecular asymmetry with more polarizable selenium substitution increases the dielectric constant of the D18/BS3TSe-4F blend, helping lower the exciton binding energy. On the other hand, dimer packing in BS3TSe-4F is facilitated to enable free charge generation, helping more efficient exciton dissociation and lowering the radiative recombination loss (ΔE₂ ) of OSCs. As a result, PMHJ OSCs based on D18/BS3TSe-4F achieve a PCE of 18.48%. By incorporating another mid-bandgap acceptor Y6-O into D18/BS3TSe-4F to form a ternary PMHJ, a higher open-circuit voltage (V_OC ) can be achieved to realize an impressive PCE of 19.03%. The findings of using pseudosymmetric electron acceptors in enhancing device efficiency provides an effective way to develop highly efficient acceptor materials for OSCs.

Keywords: electron acceptors; free charge generation; organic solar cells; planar-mixed heterojunctions; pseudosymmetry.

Abstract

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