High open-circuit voltage in transition metal dichalcogenide solar cells. (January 2021)

• Record Type: Journal Article
• Authors: Svatek, Simon A.; Bueno-Blanco, Carlos; Lin, Der-Yuh; Kerfoot, James; Macías, Carlos; Zehender, Marius H.; Tobías, Ignacio; García-Linares, Pablo; Taniguchi, Takashi; Watanabe, Kenji; Beton, Peter; Antolín, Elisa
• Is Part Of: Nano energy. Volume 79(2021)
• Publication Date: 2021-01
• Subjects: Ultra-thin photovoltaics -- Layered Materials -- Transition metal Dichalcogenides -- Low Woc; Nanoscience -- Periodicals; Nanotechnology -- Periodicals; Nanostructured materials -- Periodicals; Power resources -- Technological innovations -- Periodicals; Nanoscience; Nanostructured materials; Nanotechnology; Power resources -- Technological innovations; Periodicals; 621.042
• DOI: 10.1016/j.nanoen.2020.105427
• Languages: English
• ISSNs: 2211-2855

Abstract

Abstract: The conversion efficiency of ultra-thin solar cells based on layered materials has been limited by their open-circuit voltage, which is typically pinned to a value under 0.6 V. Here we report an open-circuit voltage of 1.02 V in a 120 nm-thick vertically stacked homojunction fabricated with substitutionally doped MoS2 . This high open-circuit voltage is consistent with the band alignment in the MoS2 homojunction, which is more favourable than in widely-used TMDC heterostructures. It is also attributed to the high performance of the substitutionally doped MoS2, in particular the p-type material doped with Nb, which is demonstrated by the observation of electroluminescence from tunnelling graphene/BN/MoS2 structures in spite of the indirect nature of bulk MoS2 . We find that illuminating the TMDC/metal contacts decreases the measured open-circuit voltage in MoS2 van der Waals homojunctions because they are photoactive, which points to the need of developing low-resistance, ohmic contacts to doped MoS2 in order to achieve high efficiency in practical devices. The high open-circuit voltage demonstrated here confirms the potential of layered transition-metal dichalcogenides for the development of highly efficient, ultra-thin solar cells. Graphical Abstract: ga1 Highlights: Open-circuit voltage in layered material photovoltaics above 1 V. Low WOC in a solar cell. Thickness for maximum absorbance ~100 nm in ultra-thin MoS2 solar cells. Indirect band gap electroluminescence in a graphene/BN/MoS2 :Nb tunnelling device. Effect of Schottky barriers on transition-metal dichalcogenide solar cells.