## 3 Results and Discussion  
The next step in our study was the analysis of the electronic structure of the formed borophene/ReS\({}_{2}\) and borophene/ReSe\({}_{2}\) van der Waals heterostructures. To this end, calculations of the band structure were carried out, and the DOS distributions were constructed based on these calculation results. Figure 4 shows the calculated DOS distributions for both borophene/ReS\({}_{2}\) (Figure 4a) and borophene/ReSe\({}_{2}\) (Figure 4b) heterostructures, and for isolated monolayers, in order to reveal the regularities in the formation of the DOS profile for van der Waals heterostructures. As can be observed from the graphs in Figure 4, the contours of the DOS profiles of the borophene/ReS\({}_{2}\) and borophene/ReSe\({}_{2}\) heterostructures largely repeat the contours of the DOS profiles of the ReS\({}_{2}\) and ReSe\({}_{2}\) isolated monolayers, respectively. At the same time, both heterostructures demonstrate a metallic type of conductivity, as evidenced by the absence of an energy gap between the valence band and conduction band. Therefore, we can say that borophene makes a decisive contribution to the type of conductivity of both heterostructures. In order to explain the obtained result, we calculated the distribution of the electron charge density over the atoms of the borophene/ReS\({}_{2}\) and borophene/ReSe\({}_{2}\) supercells according to the Mulliken procedure [PERSON] (1958). Based on the obtained distributions, it was revealed that a charge transfer occurred from borophene to ReS\({}_{2}\)/ReSe\({}_{2}\). The total value of the transferred charge to the ReS\({}_{2}\) layer was 0.76e, and to the ReSe\({}_{2}\) layer, it was 0.11\(e\). The difference in the value of the charge transferred by borophene is explained, on the one hand, by the difference in the distance between the borophene and ReS\({}_{2}\)/ReSe\({}_{2}\) layers along the z-axis. In the case of the borophene/ReS\({}_{2}\) heterostructure, the layers are closer to each other (2.96 A), which means that the charge transfer is more intense. In the case of the borophene/ReSe\({}_{2}\) heterostructure, the layers are farther apart (3.03 A). On the other hand, the difference in the value of the charge transferred by borophene can be caused by the fact that sulfur has higher electronegativity, according to [PERSON] (6.22 eV), as compared to selenium (5.89 eV). Figure 4: DOS of borophene/ReS\({}_{2}\) (**a**) and borophene/ReSe\({}_{2}\) (**b**) van der Waals heterostructures. Optoelectronic Properties of Borophene/ReS\({}_{2}\) and Borophene/ReSe\({}_{2}\) van der Waals Heterostructures  
Next, we analyze the optoelectronic properties of borophene/ReS\({}_{2}\) and borophene/ReSe\({}_{2}\) van der Waals heterostructures. This analysis was carried out on the basis of the calculated absorption spectra in the wavelength range of electromagnetic radiation, from 200 to 2000 nm, and spectra of the photocurrent. The calculated absorption spectra are shown in Figure 5. To reveal the regularities in the formation of the profile of the absorption spectra of the heterostructures, the absorption spectra of isolated monolayers of borophene and ReS\({}_{2}\)/ReSe\({}_{2}\) were calculated, which are also shown in Figure 5.  
Analysis of the absorption spectra profiles showed that both heterostructures are characterized by the appearance of two noticeable peaks in the UV range. In the absorption spectrum of the borophene/ReS\({}_{2}\) heterostructure, these peaks are located in the far (\(\lambda\) = 130 nm) and near-UV ranges (\(\lambda\) = 268 nm). Moreover, the peak in the near-UV region is due to the contribution of ReS\({}_{2}\), and the peak in the far-UV region is due to the contribution of borophene. Consequently, there is a synergistic effect of the combination of borophene and ReS\({}_{2}\), leading to an increase in the absorption capacity of the borophene/ReS\({}_{2}\) heterostructure in the UV range. At the same time, in the near-IR region (0.75-2 um), the absorption coefficient is minimal and is no more than 3%.