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Optoelectronic properties of hyperbranched polythiophenes
Hannah S Mangold1, Thomas V Richter, Steffen Link
1Freiburg Institute for Advanced Studies (FRIAS) & Institut für Makromolekulare Chemie, Universität Freiburg, Freiburg, Germany.
The Journal of Physical Chemistry. B
|December 29, 2011
Summary
Branched polythiophenes offer isotropic charge transport for organic solar cells. These novel materials show promising optoelectronic properties and higher open-circuit voltages compared to linear poly(3-hexylthiophene).
Area of Science:
- Materials Science
- Organic Electronics
- Polymer Chemistry
Background:
- Conventional linear conjugated polymers like poly(3-hexylthiophene) (P3HT) are widely used in organic solar cells.
- Branched conjugated architectures offer potential advantages in charge transport properties.
Purpose of the Study:
- To investigate the optoelectronic properties of branched poly(thiophene)s (p3T and p4T).
- To evaluate their potential for use in organic solar cell devices.
- To compare their performance against linear P3HT.
Main Methods:
- Synthesis of branched poly(thiophene)s (p3T and p4T) via oxidative coupling.
- Optical characterization in solution and thin films.
- Cyclic voltammetry for energy level determination.
- Fabrication and testing of organic solar cell devices.
Main Results:
- Branched polythiophenes exhibit lower HOMO and LUMO energy levels than P3HT.
- Field effect mobilities were measured to be around 10(-4) cm(2)/(V s).
- Solar cell devices achieved efficiencies of 0.6% with significantly higher open-circuit voltages (up to 714 mV) compared to P3HT.
Conclusions:
- Branched polythiophenes are suitable model systems for amorphous conjugated materials.
- Their optoelectronic properties suggest applicability in organic solar cells.
- The observed higher open-circuit voltages present a significant advantage over P3HT-based devices.
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