Abstract: Graphene has been intensively studied in photovoltaics focusing on emerging solar cells based on thin films, dye-sensitized solar cells, quantum dots, nanowires, and so forth. However, the typical efficiency of these solar cells incorporating graphene is below 16%. Therefore, the photovoltaic potential of graphene has not yet been shown. In this work, the use of graphene for concentration applications on III-V multijunction solar cells, which indeed are the solar cells with the highest efficiency, is demonstrated. First, a wide optoelectronic characterization of graphene layers is carried out. Then, the graphene layer is incorporated onto triple-junction solar cells, which decreases their series resistance by 35% (relative), leading to an increase in fill factor of 4% (absolute) at concentrations of 1000 suns. Simultaneously, the optical absorption of graphene produces a relative short-circuit current density decrease in the range of 0% to 1.8%. As a result, an absolute efficiency improvement close to 1% at concentrations of 1000 suns was achieved with respect to triple-junction solar cells without graphene. The impact of incorporating one and two graphene monolayers is also evaluated.

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