Tunable electron and hole injection channels at plasmonic Al-TiO₂ interfaces

Area of Science:

• Plasmonics and Nanophotonics
• Materials Science
• Photocatalysis and Photovoltaics

Background:

• Metallic nanostructures absorb light via plasmon excitations, generating hot electron-hole pairs.
• Efficient charge separation at metal-semiconductor interfaces is crucial for photovoltaic and photocatalytic applications.
• Aluminum's high plasmon frequencies, extending into the ultraviolet, offer potential for advanced applications.

Purpose of the Study:

• To investigate plasmon excitations and charge separations at Aluminum-Titanium Dioxide (Al-TiO2) interfaces.
• To explore the role of first-principles quantum-mechanical calculations in understanding these phenomena.
• To identify tunable pathways for hot-carrier generation and separation in plasmonic systems.

Main Methods:

• Quantum-mechanical calculations treating atomic structures and electronic dynamics from first-principles.
• Analysis of plasmon excitations and hot-carrier distributions at Al-TiO2 interfaces.
• Investigation of charge separation mechanisms influenced by semiconductor band gaps and plasmon properties.

Main Results:

• High-frequency Al plasmons generate abundant, broad-band hot-carrier distributions.
• The semiconductor band gap breaks electron-hole symmetry, leading to asymmetric hot-carrier distributions.
• Two competing charge separation channels are identified, controllable by laser frequency or nanostructure design.

Conclusions:

• Aluminum plasmons provide a versatile and tunable pathway for charge transfer and separation.
• The findings have general implications for advancing plasmon-assisted photovoltaics and photocatalysis.
• Control over hot-carrier dynamics through plasmon engineering is demonstrated.