Photo-Carrier-Guiding Behavior of Vertically Grown MoS2 and MoSe2 in Highly Efficient Low-Light Transparent Photovoltaic Devices on Large-Area Rough Substrates.

Abstract

Two-dimensional MoX2 (X = S, Se) films were vertically grown on highly rough transparent conducting F-doped SnO2 glass substrates for the first time and successfully used as photogenerated carrier-guiding layers (CGLs) in transparent hydrogenated amorphous silicon (a-Si:H) thin film solar cells (TFSCs). The MoSe2 CGL layers could be grown at 530 °C using thermally cracked small Se-molecules on transparent FTO glass substrates and significantly improved cell performance. A transparent cell transmitting 26.0% of visible light with a 20 nm-thick vertically grown MoSe2 CGL showed an outstanding power conversion efficiency of 27.1% at a light intensity of 0.16 mW cm-2 (500 lx; corresponding to normal indoor irradiation). The shunt resistance (Rsh) of the TFSCs reached 32,000 Ω at a light intensity of 7 mW cm-2. An Rsh value this large is essential for low-light photovoltaic (PV) devices to prevent the dissipation of photogenerated carriers. These results strongly demonstrate that transparent a-Si:H-TFSCs with vertically grown MoX2 films should find wide use in building-integrated PV windows or indoor PV applications, as they can generate power even in very low-light environments.