@article{bibcite_8610,
  author = {Y. Zhao and P. Westerik and R. Santbergen and E. Zoethout and H. Gardeniers and A. Bieberle},
  title = {From Geometry to Activity: A Quantitative Analysis of WO3/Si Micropillar Arrays for Photoelectrochemical Water Splitting},
  abstract = {The photoelectrochemical (PEC) activity of microstructured electrodes remains low despite the highly enlarged surface area and enhanced light harvesting. To obtain a deeper understanding of the effect of 3D geometry on the PEC performance, well-defined WO3/n-Si and WO3/pn-Si micropillar arrays are fabricated and subjected to a quantitative analysis of the relationship between the geometry of the micropillars (length, pitch) and their PEC activity. For WO3/n-Si micropillars, it is found that the photocurrent increases for WO3/n-Si pillars, but not in proportion to the increase in surface area that results from increased pillar length or reduced pillar pitch. Optical simulations show that a reduced pillar pitch results in areas of low light intensity due to a shadowing effect. For WO3/pn-Si micropillar photoelectrodes, the p{\textendash}n junction enhances the photocurrent density up to a factor of 4 at low applied bias potential (0.8 V vs RHE) compared to the WO3/n-Si. However, the enhancement in photocurrent density increases first and then decreases with reduced pillar pitch, which scales with the photovoltage generated by the p{\textendash}n junction. This is related to an increased dead layer of the p{\textendash}n junction Si surface, which results in a decreased photovoltage even though the total surface area increases.
},
  year = {2020},
  journal = {Advanced Functional Materials},
  volume = {30},
  pages = {1909157},
  month = {03/2020},
  doi = {10.1002/adfm.201909157},
  language = {eng},
}