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Revealing the Molecular Weight Effect on Highly Efficient Polythiophene Solar Cells
Youle Li1, Xiyue Yuan1, Seoyoung Kim2
1Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou 510640, Guangdong, China.
ACS Applied Materials & Interfaces
|June 9, 2023
Summary
Optimizing the molecular weight of polythiophenes (PTs) enhances organic solar cell (OSC) performance. Higher molecular weights lead to improved power conversion efficiency (PCE) and stability in PT-based OSCs.
Area of Science:
- Materials Science
- Organic Electronics
- Photovoltaics
Background:
- Polythiophenes (PTs) are key electron donors in organic solar cells (OSCs).
- Rational molecular design has significantly improved PT solar cell power conversion efficiency (PCE).
Purpose of the Study:
- To investigate the effect of molecular weight on the morphology and performance of polythiophene (P5TCN-F25) in organic solar cells.
- To optimize molecular weight for enhanced photovoltaic properties and device stability.
Main Methods:
- Synthesis of five batches of P5TCN-F25 polythiophene with varying molecular weights (30–87 kg mol-1).
- Systematic investigation of blend film morphology and photovoltaic performance.
- Characterization of phase separation and molecular packing.
Main Results:
- Power conversion efficiencies (PCEs) increased with molecular weight, reaching a maximum of 16.7% in binary PT solar cells.
- Improved performance is attributed to finer phase separation and more compact molecular packing in blend films.
- Higher molecular weights correlated with enhanced device stability.
Conclusions:
- Optimizing polythiophene molecular weight is crucial for high-performance organic solar cells.
- This study provides insights for further enhancing PCE in PT-based OSCs.
- High molecular weight polymers offer improved device stability.
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