  This study focuses on enhancing the electrical and thermoelectric properties
of tungsten trioxide (WO$_3$) thin films using the spray pyrolysis technique.
Three samples, namely A$_1$, A$_2$, and A$_3$, were prepared by depositing the
films onto glass substrates at different deposition rates: R$_1=1$ mL/min,
R$_2=3$ mL/min, and R$_3=7$ mL/min, respectively. Subsequently, the films
underwent annealing at 500 $^\circ$C for 2 hours in air. A detailed
investigation was conducted to analyze the structural, morphological, optical,
and electrical properties of the $\mathrm{WO}_3$ thin films. The FE-SEM images
revealed the formation of circular strings with varying diameters for all
layers. The diameter of each string decreased as the deposition rate increased.
XRD structural analysis indicated that, before annealing, sample R$_1$
exhibited a polycrystalline nature with mixed tetragonal-hexagonal phases,
while the other two samples were amorphous. After annealing, sample A$_3$ also
became polycrystalline. Moreover, the UV-Vis spectra analysis demonstrated a
monotonic decrease in the band gap of the layers with increasing spray rate,
potentially attributed to the attenuation of the quantum confinement effect.
The Seebeck effect was used to authenticate the $n$-type conductivity of the
WO$_3$ layers, as the Seebeck effect and conductivity exhibited a direct
connection. Furthermore, the current-voltage variation was found to align with
the oxygen vacancies sites. Remarkably, the sample A$_3$ with the highest
deposition rate exhibited the lowest resistivity.
