Atomic Layer Deposition of Defective Amorphous TiO Thin Films with Improved Photoelectrochemical Performance

Area of Science:

• Materials Science
• Photochemistry
• Nanotechnology

Background:

• Controlling defects in titanium dioxide (TiO₂) thin films is crucial for enhancing photoelectrochemical (PEC) efficiency in water splitting.
• Understanding the impact of defects on TiO₂ thin film PEC performance is essential for optimizing water splitting technologies.

Purpose of the Study:

• To investigate the correlation between defect concentration and PEC performance in amorphous TiO₂ thin films.
• To explore the role of growth temperature in controlling defects during atomic layer deposition (ALD) of TiO₂.
• To provide insights into the PEC properties of defective amorphous ALD-TiO₂ thin films.

Main Methods:

• Amorphous TiO₂ thin films were prepared using atomic layer deposition (ALD) at various growth temperatures.
• X-ray photoelectron spectroscopy (XPS) and electron spin resonance (ESR) spectroscopy were employed to analyze defect concentration.
• Ultraviolet-visible (UV-Vis) absorption spectroscopy was used to evaluate light absorption properties.

Main Results:

• Defect concentration in TiO₂ thin films was successfully controlled by adjusting the ALD growth temperature.
• The TiO₂ film grown at 200 °C exhibited the highest defect concentration and a photocurrent density of 0.051 mA/cm² at 1.23 V vs RHE.
• Light absorption, photogenerated charge separation, and charge transfer efficiencies were correlated with defect concentration.

Conclusions:

• Growth temperature is an effective parameter for controlling defects in amorphous ALD-TiO₂ thin films.
• Optimizing defect concentration in TiO₂ thin films can significantly enhance PEC water splitting performance.
• This research offers valuable insights for designing advanced TiO₂-based photoelectrodes.