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Lecture

Utilizing a femtosecond laser for structuring of TiO2 thin films produced by PECVD for photoelectrochemical water splitting.

Wednesday (28.09.2016)
15:30 - 15:45
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PECVD (plasma enhanced chemical vapor deposition) as a method for producing thin film layers has several advantages including high reproducibility, good step coverage and low operation temperature. This process can be used to produce photoelectrodes of different materials such as carbides, nitrides and mainly oxides as thin-films on FTO-substrates for PEC (photoelectrochemical) water splitting. TiO2 is a well known oxide with several advantages such as stability in wide pH range, low-cost and non-toxicity. However, the high band gab of TiO2 (3.2 eV) allows it to absorbs only the UV-region of the solar light. Through different modifications, like increasing the amount of Ti3+, it's bandgap can be reduced, and the absorption, especially in the visible region, increases.


Defects in the TiO2-lattice can be introduced by different methods, for example by using femtosecond laserpulses. The short pulse duration ensures that the layer won't be damaged through longer absorption of the beam, and parameters like beam width, laser power or how much the different spots overlap can be varied. This laser structuring changes the property of the TiO2 layer, like absorption or conductivity, which changes the PEC-performance.


In this study, we are presenting a disordered TiO2 layer for photoelectrochemical water splitting. TiO2 thin films were prepared by PECVD. These samples were used to optimize different parameters in the laser structuring process, like beam width, laser power or overlapping of the spots, and the optimized parameters used to structure an area of about 1 cm². This was used to see the impact of the laser structuring on the properties, like UV-Vis absorption, conductivity or PEC performance.

 

Speaker:
Danny Bialuschewski
University of Cologne
Additional Authors:
  • Jan Hoppius
    Ruhr-Universität Bochum
  • Prof. Dr. Evgeny Gurevich
    Ruhr-Universität Bochum
  • Dr. Yakup Gönüllü
    University of Cologne
  • Prof. Dr. Sanjay Mathur
    University of Cologne