Optically Active TiO₂:Er Thin Films Deposited by Magnetron Sputtering.

Area of Science:

• Materials Science
• Nanotechnology
• Photochemistry

Background:

• Titanium dioxide (TiO₂) photoanodes for hydrogen generation have limited solar-to-chemical efficiency due to poor solar spectrum absorption.
• Optically active materials are crucial for improving the efficiency of solar energy conversion.

Purpose of the Study:

• To investigate the properties of erbium-doped TiO₂ (TiO₂:Er) thin films for enhanced photoanode applications.
• To address the mismatch between TiO₂ optical absorption and the solar spectrum for improved hydrogen generation.

Main Methods:

• TiO₂:Er thin films were fabricated using radio frequency (RF) magnetron sputtering under ultrahigh vacuum (UHV) conditions.
• Characterization included analysis of morphology, structural, optical, and electronic properties.

Main Results:

• Homogeneous TiO₂:Er thin films with uniform Er ion distribution and high visible light transparency were obtained.
• A significant 0.4 eV blue shift in the absorption edge was observed, attributed to amorphization or Er₂Ti₂O₇ nanocrystal precipitation.
• Demonstrated near-infrared (NIR) to visible (VIS) up-conversion upon 980 nm excitation and strong green photoluminescence upon 488 nm excitation.

Conclusions:

• Erbium doping modifies the optical properties of TiO₂ thin films, potentially enhancing their performance in solar energy applications.
• The observed up-conversion and photoluminescence properties suggest potential for improved light harvesting and hydrogen generation.