MoS2 solar cell with 120 nm-absorber and 3.8% AM1.5G efficiency

Recent research on semiconductor materials with layered crystalline structure, like the transition metal dichalcogenides (TMDCs) MoS2 and WeS2, has opened the path to the realization of ultrathin, ultralight microelectronic devices. TMDCs enable the exfoliation or growth of ultrathin laminae - from a monolayer to hundreds of nm thick - that have self-passivated surfaces and are mechanically and chemically stable. Furthermore, applying just mechanical methods several laminae can be assembled at room temperature to form a device (a van der Waals structure). Among the potential applications of TMDCs, the development of ultrathin solar cells is attracting attention because of the possible reduction in cost and in semiconductor material consumption, and because of the suitability of these materials for flexible and ultralight photovoltaics. In this work, a 120 nm thick MoS2 p-n junction is presented. We have developed a straightforward method to fabricate ohmic contacts to both n and p MoS2 and we have added an h-BN layer on top of the semiconductor to minimize the reflectance of the front surface. The homojunction device exhibits (3.8 ± 0.2)% efficiency and 57% fill factor under AM1.5G illumination. This work contributes to the maturity of the emerging technology of TMDC-based ultrathin solar cells.