Achieving 19% Power Conversion Efficiency in Planar-Mixed Heterojunction Organic Solar Cells Using a Pseudosymmetric
Wei Gao1,2, Feng Qi2,3, Zhengxing Peng4
1Department of Materials Science and Engineering, City University of Hong Kong, Kowloon, 999077, Hong Kong.
Advanced Materials (Deerfield Beach, Fla.)
|June 20, 2022
Summary
Researchers achieved a record power conversion efficiency (PCE) over 19% in organic solar cells (OSCs) using a novel asymmetric selenium-substituted electron acceptor. This strategy enhances charge generation and reduces energy loss, paving the way for more efficient solar energy conversion.
Area of Science:
- Materials Science
- Organic Electronics
- Photovoltaics
Background:
- Organic solar cells (OSCs) offer a promising alternative to conventional silicon photovoltaics due to their flexibility and low manufacturing costs.
- Achieving high power conversion efficiency (PCE) in OSCs remains a key challenge, often limited by exciton binding energy and charge recombination.
- Planar-mixed heterojunction (PMHJ) architectures have shown potential for improved device performance.
Purpose of the Study:
- To develop a novel pseudosymmetric electron acceptor with enhanced properties for OSCs.
- To investigate the impact of asymmetric selenium substitution on the electronic and morphological properties of the electron acceptor.
- To achieve record PCE in PMHJ OSCs through strategic molecular design and ternary blending.
Main Methods:
- Synthesis of a novel pseudosymmetric electron acceptor, BS3TSe-4F, featuring asymmetric selenium substitution.
- Fabrication of PMHJ OSCs using the D18/BS3TSe-4F blend.
- Formation of ternary PMHJ OSCs by incorporating a mid-bandgap acceptor (Y6-O) into the D18/BS3TSe-4F system.
- Characterization of device performance, including PCE, open-circuit voltage (VOC), and exciton dynamics.
Main Results:
- The asymmetric selenium substitution in BS3TSe-4F increased the dielectric constant of the D18/BS3TSe-4F blend, effectively lowering exciton binding energy.
- Facilitated dimer packing of BS3TSe-4F promoted efficient free charge generation and exciton dissociation.
- PMHJ OSCs based on D18/BS3TSe-4F achieved a PCE of 18.48%.
- Ternary PMHJ OSCs incorporating Y6-O achieved a record PCE of 19.03% with a higher VOC.
Conclusions:
- Asymmetric selenium substitution in pseudosymmetric electron acceptors is an effective strategy for enhancing OSC performance.
- The developed BS3TSe-4F acceptor and ternary blending approach significantly improve charge generation and reduce recombination losses.
- This work provides a valuable pathway for designing next-generation high-efficiency acceptor materials for organic solar cells.
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