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Highly Efficient Non-Fused-Ring Electron Acceptors Enabled by the Conformational Lock and Structural Isomerization
Jun Zhao1, Xiaopeng Xu2, Liyang Yu2
1College of Chemistry and State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu 610065, P. R. China.
ACS Applied Materials & Interfaces
|May 20, 2021
Summary
Two new nonfused-ring electron acceptors (N-FREAs) were synthesized. Isomerization significantly improved power conversion efficiency (PCE) in organic solar cells from 3.97% to 10.66%.
Area of Science:
- Materials Science
- Organic Electronics
- Photovoltaics
Background:
- Nonfused-ring electron acceptors (N-FREAs) are crucial for high-performance organic solar cells.
- Molecular design and structural isomerization significantly impact N-FREA properties and device performance.
- Controlling molecular packing and charge transport is key to enhancing power conversion efficiency (PCE).
Purpose of the Study:
- To design and synthesize novel nonfused-ring electron acceptors (N-FREAs) with tunable properties.
- To investigate the effect of structural isomerization on molecular conformation, packing, and electronic properties.
- To improve the power conversion efficiency (PCE) of organic solar cells through rational molecular design.
Main Methods:
- Synthesis of two novel N-FREAs, DTP-out-F and DTP-in-F, featuring a 2,5-difluorophenylene core and DTP blocks.
- Analysis of molecular conformation and noncovalent interactions (C-H···F) influencing planarity.
- Investigation of structure-property relationships, including optical absorption and molecular packing.
- Fabrication and characterization of organic solar cell devices to evaluate power conversion efficiency (PCE).
Main Results:
- DTP-in-F and DTP-out-F were successfully synthesized, exhibiting planar conformations locked by C-H···F interactions.
- Structural isomerization (DTP-in-F vs. DTP-out-F) led to different molecular packing behaviors.
- DTP-in-F demonstrated enhanced J-aggregation and face-on packing, resulting in red-shifted absorption and improved charge transport.
- Organic solar cells based on DTP-in-F achieved a significantly higher PCE of 10.66% compared to 3.97% for DTP-out-F.
Conclusions:
- Isomerization strategy is effective in tuning N-FREA properties for enhanced performance.
- Controlling molecular packing through structural design is critical for high-efficiency organic solar cells.
- The developed N-FREAs show great potential for future applications in organic photovoltaics.
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