## 4 Conclusions  
Heterojunction with intrinsic thin layer cells was optimized to operate under the AM1.5 standard spectrum and the Atacama Desert spectrum, varying the thicknesses and number of carriers in the different layers, and the resulting characteristics for each layer are shown in Table 5. The results show that when modeling under the Atacama spectrum, an  
Figure 8: Reflectance, absorbance, transmittance, and external quantum efficiency. The solid line indicates that TCO is ITO. The dashed lines indicate that TCO is graphene. optimized cell has a higher efficiency than under the AM1.5 spectrum, with a percentage difference of 6.89% (the absolute values are shown in Table 4). For the modeling of graphene as transparent conductive film, the number of graphene layers was varied from 1 to 10 layers. Under both spectra, the optimum number is three graphene layers, achieving efficiencies of 18.8% and 20.1% for the Standard and the Atacama spectra, respectively. However, the use of graphene instead of ITO decreased the efficiency of the cell in 13% for AM1.5. A similar result was obtained in the experimental work of [PERSON] et al. [15]: they reported a decay of 30% when they used a graphene layer with a Niquel grid instead of ITO in organic cells. A similar decay was obtained in the experiment of [PERSON] et al. [21], who used several graphene layers as AZO replacement in HIT cells. Their best result was achieved for four and five graphene layers, but the efficiencies were \(\sim\)35% lower compared to the use of AZO. [PERSON] et al. [22] deposited graphene on top of the ITO film in HIT cells and obtained an increment of 1.6% after the deposition of one graphene layer, while the addition of more layers resulted in a poorer performance compared to bare ITO. The contribution that graphene can make to the cell with the busbars was estimated, varying the number of busbars in the square solar cell of 244.315 cm\({}^{2}\), and the modeling showed us that for more than seven busbars, there were cells of greater efficiency. Although the deposition of graphene on the \(\mathrm{a-Si:H(p)}\) emitter gave lower values of the electrical characteristics, the results are still encouraging when analyzing the results of the quantum efficiency in the range of the ultraviolet spectrum, and this may have relevance to spectra such as the Atacama Desert spectrum or the extraterrestrial spectra. When graphene is the transparent conducting electrode, quantum efficiency has a higher value in the ultraviolet range, which shows that it may be convenient to use graphene-based solar cells in places where ultraviolet intensity is high. Conceptualization, P.F. ; methodology, H.R. and P.F. ; software, H.R. and P.F. ; validation, H.R. and P.F. ; formal analysis, H.R. and P.F. ; investigation, H.R. and P.F. ; resources, P.F. ; data curation, H.R. ; writing--original draft preparation, H.R. ; writing--review and editing, P.F., P.M., A.M. and V.C; visualization, H.R. ; supervision, P.F., P.M., A.M. and V.C. ; project administration, P.F. ; funding acquisition, P.F. All authors have read and agreed to the published version of the manuscript. This research was founded by ANID/FONDECYT/11190289 project, as well as ANID/FONDAP/1522A0006 \"Solar Energy Research Center, SERC-Chile\"; ANID-Fondecyt 1210490; ANID-ECOS210038-C21E08 and ANID--Millennium Science Initiative Program--NNBP # NCN2021_021. In addition, we recognize the support of the Graduate School at the Universidad de Antofagasta. A. Marzo would like to thank the Ramon y Cajal contract (RYC2021-031958-I), funded by the Spanish Ministerio de Ciencia e Innovacion MCIN/AEI/10.13039/501100011033 and by the European Union \"NextGenerationEU/PRTR\". Not applicable. Data Availability Statement: Data available on request. We recognize the support of Helmholtz-Zentrum Berlin for providing the AFORS-HET simulation software. The authors declare no conflict of interest. Figure 13: \(a-Si:H(n^{+})\) optimization, according to donor concentration.