Vertically aligned tungsten oxide nanorod film with enhanced performance in photoluminescence humidity sensing

• WO3 film with monoclinic phase was successfully synthesized by using CVD technique.
• The uniform WO3 nanorods were vertically aligned on Si substrate with high density.
• PL type humidity sensing device was directly established based on the nanorod film.
• It shows excellent sensitivity, repeatability, and response/recovery performance.
• Subsurface oxygen vacancies have played a pivotal role in the sensing application.

Vertically aligned uniform WO3 nanorod film has been successfully synthesized by using chemical vapor deposition (CVD) technique without any catalyst. X-ray diffraction (XRD), Raman spectrum, field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) images indicate that the as-prepared WO3 nanorod film is monoclinic phase and consists of densely-aligned single crystalline nanorods with diameters approximately 30–110 nm and lengths around 1 μm. A room temperature photoluminescence-type humidity sensing device based on this WO3 nanorod film integrated with Si supported substrate has been directly established to investigate their humidity sensing properties, which presents its high response, excellent linearity, quick response/recovery performance and reliable repeatability toward a very wide humidity range. Further comparison with the WO3 control sample without oxygen vacancy or defect which has poor response demonstrates that oxygen vacancies in the structure play a pivotal role in the high response humidity sensing application.

Morphology of the synthesized WO3 nanorod film and room temperature time profile of PL intensity of the WO3 film-based sensor exposed to 65% RH (relative humidity).Figure optionsDownload as PowerPoint slide