ML-MoS2 synthesis and transfer: ML-MoS2 films were grown via MOCVD on sapphire substrates according to Sebastian et al . Molybdenum hexacarbonyl (Mo(CO)6) and hydrogen sulfide (H2S) served as the Mo and S sources. H2 served as the carrier gas. The samples were transfer to a 25 mm×75 mm×1.1 mm ITO coated glass substrates (Delta Technologies Part No. CB-40IN-S111, Rs=4-10 Ω) using a polymethyl-methacrylate (PMMA)-assisted wet transfer process. First, PMMA (IMM, 495K A5) was spin-coated on the ML-MoS2 covering the sapphire substrate. The PMMA-coated sample was immersed in a 1 M NaOH solution at 70 °C to separate the PMMA/ML-MoS2 film from the sapphire substrate. The separated film was then rinsed multiple times inside a water bath and finally transferred onto the target ITO substrate. The rinsed film was lifted from the water bath using the ITO and dried with N2 gas.