## 3 Results and Discussion
### Photoconversion Efficiency of the DSSCs Fabricated Using the AZ Films  
The AZ films obtained were used for DSSCs fabrication and the photoconversion efficiency was evaluated. Figure 10a shows the J-V curves of the fabricated DSSCs using AZ films with different deposition cycles. From Figure 10a, the current density of the DSSCs obtained using AZ-I, AZ-II and AZ-III are 1.64, 4.62 and 0.70 mA cm\({}^{-2}\), respectively. The highest current density is obtained using the AZ-II sample indicating a rather dense ZnO film generating a better electron conductive pathway for the photogenerated electron from the ZnO to the FTO substrate. Severe abrasion and the presence of ZnO particle agglomerates resulted in the lowest current density of 0.70 mA cm\({}^{-2}\) as the poor interparticle connectivity could lead to electron recombination. Similar phenomenon has been reported by [PERSON] and [PERSON] using aerosol-deposited TiO\({}_{2}\) porous films and subsequent heat treatment of the films (at 450 \({}^{\circ}\)C) improved the connectivity of the particles leading to higher PCE [46]. The photoconversion efficiency (PCE) % was determined using the following Equation (2):  
\[PCE=\frac{I_{SC}V_{OC}FF}{P_{in}}\times 100\% \tag{2}\]  
where, \(J_{SC}\) is the short circuit photocurrent density, \(V_{OC}\) is the open circuit photovoltage, \(FF\) is the fill factor and \(P_{in}\) is the incident light density (100 m W/cm\({}^{2}\)). The calculated PCE % of the AZ films are shown and compared in Figure 10b. The PCE % obtained increased from 0.73 to 1.78% when the deposition cycle was increased from one (AZ-I) to two (AZ-II). However, the PCE % deteriorated to 0.19% after the three deposition cycles (AZ-III). The result indicates that the formation of less dense ZnO film with agglomerated particles on the surface of the AZ-III sample resulted in a poor PCE of the DSSC. A dense and compact aerosol-deposited ZnO film can suppress electron-hole recombination during PCE evaluation. In a study reported by [PERSON] and [PERSON], they investigated the DSSCs performance of aerosol-deposited multilayer titanium dioxide (TiO\({}_{2}\)) films and the effect of a compact TiO\({}_{2}\) layer [46]. They demonstrated that a presence of compact TiO\({}_{2}\) layer between FTO substrate and subsequent TiO\({}_{2}\) film deposition resulted in higher DSSC performance due to a reduced electron recombination. It is noteworthy that a mixture of TiO\({}_{2}\) particles with the size of 700 and 25 nm were used while the thickness of aerosol-deposited TiO\({}_{2}\) films obtained in their study ranged from 15-17 \(\upmu\)m. Moreover, the repetitive bombardment of ZnO particles could have caused abrasion and generated crystal defects that adversely affected the PCE of the assembled DSSC. The crystal defects in the AZ-III film, i.e., interstitial oxygen (O\({}_{\text{i}}\)), which are determined from the RTPL analysis, indicate that electron-hole recombination at these defects led to significant deterioration of the PCE. Figure 10c shows the incident-photon-to-current conversion efficiency (IPCE) curves obtained as a function of excitation wavelengths between 400-700 nm using the assembled DSSCs. The curves indicate the active IPCE response of the AZ films. The IPCE of the AZ-II samples exhibited a maximum IPCE at wavelength of 510 nm, with a 52% IPCE using the AZ-II sample. The IPCE result is consistent with the UV-Vis results obtained in Figure 8, indicating that the AZ-II sample possesses the best absorbance compared to AZ-I and AZ-III samples. Table 3 summarizes AZ films based DSSCs versus its structural, electrical, optical, and photovoltaic performance by various deposition cycles. The findings from this study indicates that aerosol-deposited ZnO films can be used for DSSC. Although further optimization, elucidation and control deposition of desired AD films are still required, the feasible rapid film deposition at room temperature possesses good potential for future development of scalable and affordable solar cells.