## 3 Analysis of Results  
The investigation of the I-shaped design and thin wire design is analyzed using COMSOL Multiphysics. The simulation is done based on the FEM. The result for the I-shaped design and thin wire design is presented for the range of 500 nm to 3000 nm. Figure 1: Structural design of the I-shaped and thin wire metasurface solar absorber. (**a**) an I-shaped solar absorber 3D view; (**b**) an I-shaped metasurface solar absorber front view; (**c**) an I-shaped metasurface solar absorber top view; (**d**) a thin wire metasurface solar absorber top view. The size of different parameters is presented in the figure. The length, width, and height of the substrate are 7000 nm, 7000 nm, and 2500 nm, respectively. The I shape and thin wire length are 3000 nm. The total length and width of an I-shape are both 3000 nm. A thin wire has dimensions of 3000 nm in length and 500 nm in width. The figure is not up to the scale. The three-layer design with sandwiching graphene layers is visible in the figure. The wavelength band presented includes the wavelengths of the visible and infrared regions. The absorption results for these two designs are also compared in Figure 2a,b. In Figure 2b, the numerical values of the responses are presented for the average absorption, and they are compared. The I-shape metamaterial design results show an overall average absorption of 96% for the whole range, while the thin wire design shows a 95% result for the same range, which clearly shows that the I-shape metamaterial is giving optimum performance compared to the thin wire design of the metasurface-based solar absorber design. The absorption results in Figure 2 show that there are about five peaks near the perfect absorption achieved. The absorption level for this absorption peak is more than 99%, with the highest peak having an absorption of 99.5%. Thus, this proposed solar absorber is also showing perfect absorption behavior. The response in the figure shows that in the initial phase, the absorption curve is the same, but after 1500 nm, the absorption of the I-shape metamaterial design is higher compared to the thin wire metamaterial design. The change in response is achieved because of the metasurface shape, which was converted from a thin wire shape to an I-shape. The I-shape has more area compared to the thin wire shape. The increase in area increases the overall inductance, which will result in more absorption compared to the thin shape. The I-shape design is further investigated for optimal geometrical parameters. The optimization is carried out for various dimensions of the substrate and resonator. The result of this structure optimization is discussed in the following section. The electric field response of the I-shape design is studied to verify its effect on the absorption results. The absorption results of the I-shape design presented in Figure 2 can be verified by the amount of electric energy concentrated in the solar absorber, which is presented in the electric field response figure. The E-field response is investigated in Figure 3. The electric field response is presented for six different points on the wavelength spectrum. These six different wavelength points of the spectrum are identified based on the different absorption levels at those points, allowing the field energy to be explored at those different wavelength points. The different wavelength points that are investigated here are 500 nm, 1000 nm, 1500 nm, 2000 nm, 2500 nm, and 3000 nm. The six points cover the whole  
Figure 2: The metamaterial design comparative response for I-shape design and thin wire design is shown in (**a**) an absorption plot (**b**) and a comparative table with numerical data. The highest average absorption response is 96% for the I-shape metamaterial design. spectrum of wavelengths observed for absorption results. The E-field response presents that as the wavelength of investigation is increased, the absorption is also increased, and the absorption is also achieved through SiO\({}_{2}\) and GaAs substrates.