Transition metal dichalcogenides (TMDCs) are a promising class of two-dimensional (2D) materials for use in 2D electronics. This is due to an inherent band-gap that can be direct or indirect, depending on the number of layers, unlike graphene which has no bandgap in its pristine condition. For a wide range of applications, TMDC heterostructures or more broadly van der Waals (vdW) heterostructures are expected to show interesting properties due to interfacial effects. Furthermore, vdW heterostructures avoid any problems arising from lattice mismatch that affect other types of heterostructures. Current studies on heterojunctions between TMDCs have primarily focused on mechanical (or chemical) exfoliation or co-vapor growth methods. These methods are limited by the size and non-uniform distribution of the heterostructures on the substrate. Any application of TMDC heterostructures needs a viable method to produce large-area, patternable heterostructures. Recently we have demonstrated a large-area synthesis of TMDC thin films via vapor transport. In this presentation, I will discuss a one-step synthesis procedure we have developed for stacked heterostructures of multi-layer MoS2 and WS2. This heterostructure forms a p-n junction, so potential applications include the formation of thin, flexible 2D transistors. This method has the key advantage over current methods that it can be patterned, is large-area, and is suitable for scaled synthesis of devices. We have characterized our synthesized heterostructures with Raman Spectroscopy and cross-sectional transmission electron microscopy. Our device shows transport measurement consistent with what we would expect for a p-n junction device. This work lays the ground work for further studies on patterned synthesis of TMDC heterostructures.