Building two-dimensional (2D) heterostructure emerges novel properties, with promisingrnapplications in photovoltaic (PV) cells. By performing density functional theory (DFT) based firstprinciplesrncalculations,rnelectronicrnpropertiesrnofrnWS2rnandrnJanusrntransition-metalrndichalcogenidesrnrn(JTMDs)rnrnmonolayers were calculated and depending on the lattice mismatch, layered 2DrnJTMDs/WS2 heterostructures were formed. The formation of the JTMDs/WS2 van der Waalsrn(vdW) heterostructures have shown great potential for the design of novel electronic devices. Inrnthis study, Janus MoSSe/WS2, WSSe/WS2, and MoSTe/WS2 heterostructures were developed andrntheir structural and electronic properties were evaluated using first principles calculations basedrnon DFT calculations using Quantum ESPRESSO and VASP codes. It was found that thernheterostructures bandgap is smaller than the Janus TMDs and WS2 monolayer. Structuralrnrelaxations were performed using generalized-gradient approximation (GGA) approaches for bothrnthe monolayers and heterostructures. Structural stability and electronic properties of JTMDs/WS2 rnvdW heterostructures with AC and AD stacking were investigated which are the most stablernconfiguration compared with other configurations based on the binding energy and the interlayerrndistance. Results show that the Janus MoSTe/WS2, MoSSe/WS2, and AD-configuration ofrnWSSe/WS2 vdW heterostructures are indirect bandgap semiconductor, but WSSe/WS2 with ACconfigurationrnisrnarndirectrnbandgap.rnThernJTMDs/WS2rnvdWrnheterostructuresrnexhibitedrnarnbandgaprninrnrnthernrangernofrn1.54rntorn0.54eV.rnrnInrnaddition,rnMoSSe/WS2rnandrnMoSTe/WS2rnheterostructuresrndisplayedrnrnarntype-IIrnbandrnalignmentrnwhichrnisrnimportantrntornimprovernthernphotoelectricrnconversionrnefficiency.rnrnHowever,rnrnthe band alignment of WSSe/WS2 heterostructure is difficult to identify and needrnadditional calculations. First principles study shows that the investigated 2D heterostructures haverna suitable bandgap for photovoltaic applications. Among the JTMDs/WS2 vdW heterostructures,rnMoSSe/WS2 and MoSTe/WS2 manifest type-II band alignment, making them promisingrncandidates for photovoltaic (PV) applications.