Micropatterning of BiVO₄ Thin Films Using Laser‐Induced Crystallization

Abstract

Relatively high temperatures even up to 500 °C are required to obtain bismuth vanadate (BiVO4) films with the scheelite monoclinic (s‐m) structure that shows the highest photocatalytic activity. This requirement limits the possible choice of substrates. Moreover, high quality thin layers of crystalline BiVO4 cannot be prepared with current methods. In this study a light‐induced crystallization approach is presented, which is a step toward preparation and patterning of BiVO4 (s‐m) films for applications on plastic substrates. Thin films of amorphous BiVO4 are prepared by pulsed laser deposition. The possibility of using green (514.7 nm) laser illumination for crystallization of BiVO4 is investigated. The laser‐induced phase transition is tracked using Raman spectroscopy. The results are compared with those obtained from thermally annealed samples, crystalline structure of which is confirmed by measuring X‐ray diffraction. The homogeneity and quality of crystallization are verified using micro‐Raman spectroscopy imaging, while time‐dependent experiments reveal the crystallization rate. The conductivity of the crystallized region is investigated using conductive atomic force microscopy. A strong increase in the conductivity is found in the patterned regions. Experimental results demonstrate the possibility of using the laser‐induced crystallization of BiVO4 to prepare patterns of improved conductivity and semiconducting properties in comparison to amorphous surroundings.

Formation and suppression of defects during heat treatment of BiVO4 photoanodes for solar water splitting

“…Although the simplicity of such processes offers important advantages, it tends to create relatively high defect densities (>10 18 cm À3 ) in the form of intrinsic point defects (e.g., cation and oxygen vacancies) as well as non-crystalline phases. 5 While some of these defects can promote the conductivity and therefore improve the PEC performance of the photoelectrode material, 6-9 many of these defects form electronic states deep in the bandgap of the oxide. Such states act as efficient charge carrier trapping or recombination centers, resulting in short carrier lifetimes.…”

Widening of the electroactivity potential range by composite formation – capacitive properties of TiO2/BiVO4/PEDOT:PSS electrodes in contact with an aqueous electrolyte

“…Ground powder was pressed into a pellet and annealed at 500 °C for 4 h. Then, the material was ground again and pressed in a hydraulic press (Specac Ltd) for about 60 s, with a load of about 35 MPa, into a pellet that acted as a PLD target. The procedure was developed and published previously [32]. PLD was used to deposit BiVO 4 films on titania nanotubes (before annealing) or titanium foil.…”

Spin‐Coated Bismuth Vanadate Thin Film as an Alternative Electron Transport Layer for Light‐Emitting Diode Application

“…The results are in good agreement with the XRD grain size result. [43,44] The increase in particle size may influence the surface roughness of the film. It is identified that BVO5 thin film has higher surface roughness than BVO3 thin film.…”