Charging gold nanoparticles in ZnO by electric fields
M Obradovic1, M Di Vece, D Grandjean
1Laboratory of Solid State Physics and Magnetism, KU Leuven, Celestijnenlaan 200d - box 2414, B-3001, Leuven, Belgium.
Summary
Researchers electrically tuned the color of gold nanoparticles by altering their electron count. This electro-optical effect in ZnO-gold nanoparticle composites enables fast optical switching for advanced photonic devices.
Area of Science:
- Plasmonics
- Nanophotonics
- Materials Science
Background:
- Controlling plasmon resonance frequency in metal nanostructures is crucial for optics research.
- Plasmon resonance is dictated by the number of free electrons in the metal.
- Modifying electron density offers a pathway to tune plasmonic properties.
Purpose of the Study:
- To indirectly alter the free electron count in gold nanoparticles.
- To investigate the electro-optical effect on plasmon resonance frequency.
- To explore applications in fast optical switching.
Main Methods:
- Utilized a heterostructure of ZnO with embedded gold nanoparticles.
- Applied an electrical potential difference across the ZnO layer.
- Monitored shifts in ZnO optical absorption and gold nanoparticle plasmon resonance.
Main Results:
- Electrical potential induced shifts in ZnO defect energy levels, facilitating electron exchange.
- Positive charge application shifted ZnO optical absorption peak from 377 nm to 386 nm.
- Gold nanoparticle plasmon resonance shifted from 549 nm to 542 nm.
Conclusions:
- Demonstrated an electro-optical effect enabling tunable plasmon resonance in gold nanoparticles.
- This method provides a means to control nanoparticle plasmon properties via electrical means.
- The observed effect shows potential for developing fast optical switching devices.
