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Updated: Oct 11, 2025
Morphology Control for Fully Printable Organic–Inorganic Bulk-heterojunction Solar Cells Based on a Ti-alkoxide and Semiconducting Polymer
Published on: January 10, 2017
Delicately Controlled Polymer Orientation for High-Performance Non-Fullerene Solar Cells with Halogen-Free Solvent
Dong Yuan1, Guoming Qin1, Lianjie Zhang1
1Institute of Polymer Optoelectronic Materials & Devices and State Key Laboratory of Luminescent Materials & Devices, South China University of Technology, Guangzhou 510640, P. R. China.
Controlling side chain branching in conjugated polymers enables molecular orientation transitions in polymer solar cells (PSCs). This strategy enhances bulk heterojunction morphology and power conversion efficiency (PCE), leading to high-performance green-solvent processed devices.
Area of Science:
- Materials Science
- Organic Electronics
- Renewable Energy
Background:
- Molecular orientation is crucial for polymer solar cell (PSC) morphology and power conversion efficiency (PCE).
- Controlling polymer structure can influence molecular packing and device performance.
Purpose of the Study:
- To investigate the effect of side chain branching position on molecular orientation in difluoroquinoxaline-thiophene-based conjugated polymers.
- To correlate polymer orientation with bulk heterojunction morphology and PSC performance.
Main Methods:
- Synthesis of three conjugated polymers (PHT3, PHT4, PHT5) with varying side chain branching points.
- Temperature-dependent absorption spectroscopy to study polymer aggregation.
- X-ray scattering analysis to determine molecular orientation.
- Fabrication and characterization of PSC devices.
Main Results:
- Polymer aggregation ability increased in the order PHT3 < PHT4 < PHT5.
- A transition from face-on to edge-on molecular orientation was observed between PHT4 and PHT5.
- PHT4-based devices exhibited the highest PCE of 13.40% due to enhanced face-on crystallinity.
- PHT5-based devices achieved a PCE of 12.66% with stronger aggregation.
Conclusions:
- Precise control over side chain branching can induce molecular orientation transitions in conjugated polymers.
- This strategy allows for the development of high-performance, green-solvent processed polymer solar cells.
- Tailoring polymer structure is key to optimizing morphology and PCE in organic photovoltaics.
