## 3 Results and Discussion
### UV Analysis  
The absorption spectra of the ZnO thin films (Figure 3a,b) reveal peaks within the 300 to 400 nm range, with additional peaks emerging for longer deposition times, specifically at 5 min. All films consistently demonstrated reflectance values ranging from 60% to 90%, as illustrated in Figure 3c,d, indicating their suitability for application in optical devices. Furthermore, an increase in deposition time was observed to positively impact overall reflectance, signifying an enhancement in optical quality. Figure 2: XRD analysis for the deposited films at **(A)** 60 V and 3 min; **(B)** 70 V and 3 min; **(C)** 80 V and 3 min; **(D)** 60 V and 5 min; **(E)** 70 V and 5 min; and **(F)** 80 V and 5 min. Figure 3: (**a**) Absorbance at 3 min; (**b**) absorbance at 5 min; (**c**) reflectance at 3 min; (**d**) reflectance at 5 min; (**e**) Kubelka–Munk at 3 min; (**f**) Kubelka–Munk at 5 min deposition time. UV analysis of the Kubelka-Munk plots (Figure 3e,f) resulted in estimated band gap values of 3.26 eV at 3 min and 3.28 eV at 5 min for the electrophoretic deposition time. This suggests that varying the electrophoresis deposition time did not significantly affect the band gap energy of the films. Equations (2) and (3) describe the Kubelka-Munk function (F(R)) [7]:  
\[\mathrm{[F(R)\;hv]=A\;(hv\;-E_{g})^{n}}, \tag{2}\]  
In the context of UV-Vis analyses, A represents the absorbance values acquired. Here, hv denotes the photon energy, \(\mathrm{E_{g}}\) signifies the band gap values, and n assumes a value of 2 specifically in the case of direct band gap values for ZnO. \[\mathrm{F(R)=(1\;-\;R)^{2}/2R}, \tag{3}\]  
where R is the material's reflectance value analyzed by the spectrophotometer. The Tauc plot, which is a graphical representation, was used to estimate the thicknesses of the thin films represented in Table 1 based on their optical absorption spectra. The Tauc plot involves plotting the square of the absorption coefficient (\(\alpha\)) (Equation (4)) against the photon energy (hv). The intercept of the extrapolated linear portion of the curve with the energy axis provides an estimate of the band gap energy (\(\mathrm{E_{g}}\)), which, in turn, can be related to the thickness of the film. \[\alpha=\mathrm{A/d}=-\mathrm{Ln\;(1/T)/d}, \tag{4}\]  
In Equation (3), the absorption A can be estimated by the Kubelka-Munk relation, F(R), and T is the transmittance value, which can be calculated by the absorbance values in Figure 3a,b. The thicknesses of the electrodeposited films were consistently around 2 \(\mathrm{\mu}\)m, indicating that the increase in deposition time was generally not significant. However, for the films deposited at a voltage of 60 V, a slightly higher difference was observed for films deposited at 3 min (2.02 \(\mathrm{\mu}\)m) and 5 min (2.1 \(\mathrm{\mu}\)m), resulting in an increase of 4% in thickness. The uniform thickness values align with the consistent band gap values for the films. [PERSON] et al. [23] also observed that in electrophoretic deposition (EPD), changes in thickness mainly occur within the first minute, while from 3 to 6 min, the deposition rate remains relatively constant. This phenomenon can be attributed to the increase in resistance; as the thickness grows, the resistance on the FTO also increases, leading to a decrease in the deposition rate [37]. Figure 4a,b show the transmittance values for the films deposited at 3 and 5 min, respectively. All the EPD films exhibited high transmittance in the visible range of the spectrum, ranging from 75 to 95%, and very low transmittance values in the ultraviolet spectra, where photon absorption and the transition from the valence to conduction band occur. The films deposited at 5 min exhibited superior transmittance quality, particularly evident at 80 V, where it increased from 75% for the films deposited at 3 min to 95% for the films deposited at 5 min, representing a 20% improvement with a longer deposition time.