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Probe Type II Band Alignment in One-Dimensional Van Der Waals Heterostructures Using First-Principles Calculations
Published on: October 12, 2019
Electronic energy transfer in highly aligned MEH-PPV single chains
Matthew C Traub1, Girish Lakhwani, Joshua C Bolinger
1Center for Nano and Molecular Science and Technology, University of Texas, Austin, Texas 78712, USA.
The Journal of Physical Chemistry. B
|August 5, 2011
Summary
Researchers visualized energy transfer in highly ordered conjugated polymer chains using anisotropy measurements. Energy funnels efficiently to few sites, indicating multistep exciton migration over 6 nm in these polymers.
Area of Science:
- Polymer Science
- Photophysics
- Spectroscopy
Background:
- Conjugated polymers like MEH-PPV are crucial for organic electronics.
- Understanding energy transfer dynamics in single polymer chains is key to optimizing device performance.
- High molecular weight polymers often exhibit complex conformations affecting energy migration.
Purpose of the Study:
- To visualize and quantify energy transfer processes in single, highly ordered MEH-PPV chains.
- To compare experimental anisotropy data with simulations of energy transfer in model polymer chains.
- To elucidate the mechanism and distance of exciton migration in these ordered systems.
Main Methods:
- Simultaneous measurement of excitation and emission anisotropy.
- Utilizing single-chain spectroscopy on MEH-PPV samples with >70% rod-like conformations.
- Simulating energy transfer using an incoherent Förster-type mechanism.
Main Results:
- Observed increases in average anisotropy from 0.62 to 0.74 (excitation to emission).
- Confirmed energy transfer to a small number of sites with <15° dipole orientation changes.
- Simulations showed good agreement with experimental data, supporting a multistep funneling process.
- Excitons migrated an average of 6 nm before emission in ordered chains.
Conclusions:
- Energy transfer in highly ordered MEH-PPV chains is a multistep funneling process.
- Exciton migration distances are significantly larger than single-step Förster Resonance Energy Transfer (FRET) radii.
- The observed high degree of molecular order persists even at large molecular weights (850 kDa).
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