## 3 Results and Discussion
The presence of absorption in this region is due to the contribution of borophene, since there is no absorption in ReS\({}_{2}\) in the range 0.75-2 um. A similar picture was observed for the borophene/ReSe\({}_{2}\) heterostructure. One of the characteristic absorption peaks is located in the far-UV region (\(\lambda\) = 134 nm) and is due to the contribution of borophene, and the other peak is located in the near-UV region (\(\lambda\) = 300 nm) and is explained by the contribution of ReSe\({}_{2}\). In the near-IR region (0.75-2 um), absorption is due to the presence of borophene in the heterostructure, but the absorption coefficient is minimal and does not exceed 4%. Nevertheless, it should be noted that the borophene/ReS\({}_{2}\) and borophene/ReSe\({}_{2}\) heterostructures are characterized by greater absorption in the IR range, as compared, for example, with molybdenum disulfide MoS\({}_{2}\) and molybdenum diselenide MoSe\({}_{2}\), which absorb no more than 1% [49]. Based on the obtained absorption spectra and solar radiation spectra on the Earth's surface (AM1.5) and outside the Earth's atmosphere (AM0), the photocurrent spectra were calculated. The solar radiation spectra AM0 and AM1.5 were taken from the National Renewable Energy Laboratory (NREL) website [50], which shows solar spectra in the  
Figure 5: Optical absorption coefficient of borophene/ReS\({}_{2}\) (**a**) and borophene/ReSe\({}_{2}\) (**b**) van der Waals heterostructures. wavelength range of 280-2000 nm. The photocurrent spectra of the borophene/ReS\({}_{2}\) and borophene/ReSe\({}_{2}\) van der Waals heterostructures are shown in Figure 6. The photocurrent values are given for a surface area of 1 cm\({}^{2}\). Figure 6 shows that the maximum value of the photocurrent for the borophene/ReS\({}_{2}\) heterostructure falls at a wavelength of 600 nm, and is 9.36 mA cm\({}^{-2}\)\(\upmu\)m\({}^{-1}\) in the case of the spectrum AM0 and 7.81 mA cm\({}^{-2}\)\(\upmu\)m\({}^{-1}\) in the case of the spectrum AM1.5. For the borophene/ReSe\({}_{2}\) heterostructure, the photocurrent maximum is shifted closer to the left edge of the visible range and falls at a wavelength of 480 nm. In the case of the AM0 spectrum, this value is 10.19 mA cm\({}^{-2}\)\(\upmu\)m\({}^{-1}\), and in the case of the AM1.5 spectrum, it is 7.98 mA cm\({}^{-2}\)\(\upmu\)m\({}^{-1}\). Thus, for both heterostructures, the peak of the photocurrent falls within the visible range of electromagnetic radiation. One of the most important physical characteristics of optoelectronic devices is the magnitude of the integrated photocurrent or the density of the photocurrent. It is calculated as the integral of the photocurrent spectrum. Table 1 shows the calculated integral values of the photocurrent for the entire solar radiation spectrum, and for the visible range of the solar spectrum, 380-780 nm, as well as the maximum value of the photocurrent at a wavelength of 550 nm, which corresponds to the maximum power of solar radiation. For comparison, Table 1 also shows the calculated values of the above optoelectronic characteristics for graphene and borophene with the allotropic form \(\beta_{12}\). Analysis of the data in Table 1 shows that the borophene/ReS\({}_{2}\) and borophene/ReSe\({}_{2}\) heterostructures are approximately 10 times higher than graphene and borophene \(\beta_{12}\), in terms of the integral value of the photocurrent in the visible range for the AM0 and AM1.5 spectra. The value of the maximum photocurrent at a wavelength of 550 nm is also higher in van der Waals heterostructures. In terms of this indicator, they exceed graphene by more than 4 times, and borophene \(\beta_{12}\) by more than 10 times. It should also be noted that the integral photocurrent of borophene/ReS\({}_{2}\) and borophene/ReSe\({}_{2}\) heterostructures in the visible range of radiation correlates well with the photocurrent density of the graphene/MoS\({}_{2}\) heterostructure (3 mA/cm\({}^{2}\)) [51] and multilayer WS\({}_{2}\) (4.10 mA/cm\({}^{2}\)) [52] obtained in a real experiment.