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Large single-crystal domains of WS₂ are grown by chemical vapor deposition, and their photoluminescent properties under a lateral electric field are studied. We demonstrate that monolayer and bilayer WS₂ have opposite responses to lateral electric fields, with WS₂ photoluminescence (PL) substantially reduced in monolayer and increased in bilayers with increasing lateral electric field strength. Temperature-dependent PL measurements are also undertaken and show behavior distinctly different than that of the lateral electric field effects, ruling out heating as the cause of the PL changes. The PL variation in both monolayer and bilayer WS₂ is attributed to the transfer of photoexcited electrons from one conduction band extremum to another, modifying the resultant recombination pathways. This effect is observed in 2D transition metal dichalcogenides due to their large exciton binding energy and small energy …