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Transition-metal dichalcogenide materials have attracted considerable attention due to their outstanding properties, and however, the carrier collection efficiency remains a major problem for achieving high-performance electronic and optoelectronic devices. In this research, we compared the carrier transport properties of graphite and Au in contact with MoS2 (WS2) materials. The use of graphite for the drain–source electrodes significantly improves carrier collection efficiency, thus enhancing the overall electronic and optoelectronic performance of MoS2 and WS2 FETs. The device’s ON/ OFF current ratio with two graphite contact electrodes increased by about two orders of magnitude (120 and 207 for MoS2 and WS2 FETs, respectively) than that with conventional Au electrodes. Furthermore, the Gr-MoS2-Gr FET shows ultrahigh responsivity (3869 A/W), detectivity ($4.6\times10$ 12 Jones), and extraordinary short photoresponse fall time ($60 ~\mu \text{s}$). Compared with the Au-MoS2-Au FET, the fall time is reduced by about six orders of magnitude. Interestingly, the Gr-MoS2-Gr and Gr-WS2-Gr FETs demonstrate different detection mechanisms. The Gr-MoS2-Gr photodetector shows a photoconduction mechanism under the gate voltage of −10 to −6 V and a photogate mechanism under −4 to 2 V, whereas the Gr-WS2-Gr photodetector is only driven by a photoconduction mechanism. The Gr-TMDs-Gr’s outstanding electronic and photoelectrical properties hold great potential for various applications in advanced optoelectronic devices. [ABSTRACT FROM AUTHOR]