Bottom-gate transistors with mono-layer MoS2 channels and polycrystalline antimonene source/drain contact electrodes deposited at 75 °C are fabricated. Significant performance enhancement of field-effect mobility 11.80 cm2 V−1·s−1 and >106 ON/OFF ratio are observed for the device. Increasing photocurrents are also observed for the MoS2 transistor under light irradiation, which is attributed to the reduced carrier recombination at the metal/2D material interfaces. The results have demonstrated that besides the matching of work function values with the 2D material channel, the crystallinity of the contact electrodes is the other important parameter for the Ohmic contact formation of 2D material devices.