## 3 Results and Discussion
Figure 4: Depiction of the frontier orbitals along with a plot of the HOMO and LUMO energy levels for BAPCP and HAPCP, calculated using the B3 LYP-D3/def2-TZVPP level of theory. Figure 5: Cyclic voltammograms at scan rates of 30, 50, 100, and 150 mV/s for (**a**) BAPCP and (**b**) HAPCP. Figure 3: Optimized molecular structures of Disperse Blue 359 and the synthesized blue materials, calculated using B3 LYP-D3/def2-TZVPP. The solubility of the colorants in PGMEA, a solvent widely used in the display and image sensor industries, was analyzed to determine their suitability as color filter materials for image sensors [29]. The solubility of BAPCP and HAPCP in PGMEA was measured to be 1.3 wt% and 1.4 wt%, respectively, as summarized in Table 3. Compared to BAPCP, HAPCP showed a slightly higher solubility, which is attributed to the introduction of a longer hexyl group in HAPCP, improving its solubility. The incorporation of butyl and hexyl alkyl groups helps suppress molecular stacking during film formation, thereby reducing aggregation. In particular, hexyl exhibits higher solubility compared to butyl due to its longer alkyl chain, which enhances interactions with solvents. The solubility of the synthesized blue colorants was comparable to that of the commercial blue colorant, Disperse Blue 359. The thermal properties of the synthesized blue colorant materials were evaluated using thermogravimetric analysis (TGA) to determine T\({}_{\text{d}}\) at 5% weight loss, as summarized in Figure 7 and Table 4. The T\({}_{\text{d}}\) values of the synthesized compounds, BAPCP and HAPCP, were 279 \({}^{\circ}\)C and 282 \({}^{\circ}\)C, respectively. Compared to the T\({}_{\text{d}}\) value of 260 \({}^{\circ}\)C for the commercial Disperse Blue 359, both compounds exhibited over 19 \({}^{\circ}\)C higher thermal stability. This high thermal stability is important, as it meets the requirements for color filter manufacturing processes for image sensors, which typically need to withstand temperatures above 230 \({}^{\circ}\)C [30; 31]. The slightly higher T\({}_{\text{d}}\) value for HAPCP compared to BAPCP is attributed to the increased molecular weight. In conclusion, the thermal properties of the synthesized compounds suggest their potential suitability for application in image sensor fabrication processes. Figure 6: Cyclic voltammetry stability of (**a**) BAPCP and (**b**) HAPCP (scan rate: 100 mV/s). Figure 7: Thermogravimetric analysis (TGA) curves of the synthesized materials at a scan rate of 10 \({}^{\circ}\)C/min under a nitrogen atmosphere. \begin{table}
\begin{tabular}{c c c c} \hline \hline  & **Disperse Blue 359** & **BAPCP** & **HAPCP** \\ \hline Solubility [wt\%] & 1.3 & 1.3 & 1.4 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Optical properties of the synthesized materials in 1.0 \(\times\) 10\({}^{-5}\) M FGMEA solution. To assess the suitability of the synthesized pyrrole derivatives for color filters in image sensors, a solution containing an acrylic binder, the newly developed colorant, and a photo-initiator in PGMEA was prepared and applied onto a glass substrate via drop-casting to create a film. The coated color filter samples underwent a pre-bake at 100 \({}^{\circ}\)C, followed by exposure to UV light at a wavelength of 365 nm. To assess the thermal stability of the fabricated color filters, the samples were subjected to a 3 min heat treatment at 220 \({}^{\circ}\)C, and their transmittance was measured both before and after this process. The results are presented in Figure