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Efficient Size-Dependent Hot Electron Transfer from Au to TiO2 Nanoparticles
Nandan Ghorai1, Zhicheng Yang1, Sara T Gebre1
1Department of Chemistry, Emory University, 1515 Dickey Drive, Atlanta, Georgia 30322, United States.
Nano Letters
|February 14, 2025
Summary
Harvesting plasmon-induced hot carriers in metal/semiconductor systems can boost solar energy conversion. Reducing gold nanoparticle size significantly enhances hot electron transfer efficiency for improved solar cell performance.
Area of Science:
- Materials Science
- Nanotechnology
- Photovoltaics
Background:
- Plasmon-induced hot carriers at metal/semiconductor interfaces are key for solar energy conversion.
- Current efficiencies are limited, hindering practical applications.
Purpose of the Study:
- To demonstrate highly efficient plasmonic hot electron transfer.
- To investigate the impact of nanoparticle size and excitation wavelength on efficiency.
Main Methods:
- Fabrication of gold nanoparticles (Au NPs) of varying sizes (5.25 nm and 9.1 nm) on TiO2 films.
- Ultrafast laser excitation at different wavelengths (400, 500, 600 nm).
- Measurement of hot electron transfer quantum efficiency (QE).
Main Results:
- Achieved a maximum QE of 57 ± 4% with 5.25 nm Au NPs at 400 nm excitation.
- QE decreased to 20% for 9.1 nm Au NPs.
- QE showed minimal change with excitation wavelength.
- Identified contributions from interband absorption, PHET, and PICTT pathways, all increasing with smaller Au size.
Conclusions:
- Reducing plasmonic nanoparticle size is a critical strategy for enhancing hot-carrier extraction.
- Optimizing nanoparticle size can significantly improve solar energy conversion efficiencies.
