Compared to bulk materials, atomically thin materials like transition metal dichalcogenides (TMDs) offer size and tunability advantages over traditional materials in developing miniature electronic and optical devices. The 2-dimensional TMDs are of particular interest because they have potential applications in energy conversion, electronics and quantum computing. The properties of these materials can be tuned by external forces like applying tensile strain or electric fields, but until recently, nobody had identified a means of intrinsically tuning these materials for optimum photoluminescent or optoelectronic properties.