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Digital Printing of Titanium Dioxide for Dye Sensitized Solar Cells
Published on: May 4, 2016
Visible light absorption by various titanium dioxide specimens.
Vyacheslav N Kuznetsov1, Nick Serpone
1Fock Research Institute of Physics, St. Petersburg State University, Ulyanovskaya St. 1, St. Petersburg 198504, Russia.
The Journal of Physical Chemistry. B
|December 15, 2006
Summary
Visible light-active titanium dioxide (TiO2) photocatalysts exhibit absorption bands linked to oxygen vacancies and color centers, not a narrowed band gap. This finding applies to various TiO2 compositions and preparation methods.
Area of Science:
- Materials Science
- Photochemistry
- Solid State Physics
Background:
- Visible-light-active titanium dioxide (TiO2) photocatalysts are crucial for applications like environmental remediation and energy conversion.
- Understanding the mechanism behind their visible light absorption is key to optimizing their performance.
- Previous studies suggested band gap narrowing through dopant-oxygen state mixing.
Purpose of the Study:
- To analyze the absorption spectra of various TiO2 compositions under heat and photoinduction.
- To correlate observed spectra with TiO2 reduction and literature data on visible-light-active photocatalysts.
- To elucidate the origin of visible light absorption in TiO2.
Main Methods:
- Examination of heat-induced and photoinduced absorption spectra of TiO2-polymer composites.
- Analysis of absorption spectra using overlapping absorption bands (ABs) model.
- Comparison with literature data of visible-light-active TiO2 photocatalysts.
Main Results:
- Absorption spectra consistently modeled as sum of three bands: AB1 (2.90 eV), AB2 (2.55 eV), and AB3 (2.05 eV).
- Spectra correlate with reduced TiO2 and are similar across different preparation methods.
- Average spectra well-described by AB1 and AB2.
Conclusions:
- Visible light activation of TiO2 is attributed to defects, specifically oxygen vacancies forming color centers.
- These color centers cause the observed absorption bands.
- The mechanism does not involve a narrowed band gap due to dopant-oxygen state mixing.
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