Two-dimensional (2D) transition metal dichalcogenide (TMD) family has the potential to be used as an active material for the next-generation p-n junction (opto-) electronics devices thanks to its fascinating electronic, optical, and physical properties. Lack of homogenously p- and n-type doped 2D-TMD due to the doping challenge during growth is one of main challenges. Beyond the conventional doping techniques during growth, several approaches such as plasma, thermal, chemicals, etc. have been employed to achieve p- and n-type 2D-TMDs. In this study, suspended and substrate-supported n- and p-type MoS2, WS2, and WSe2-based p-n junction diodes were fabricated, and the effect of traditional doping and post-growth doping on the diode parameters and emission profile of the devices were investigated. Free-standing junctions show better electrical and optical properties compared to substrate-supported diodes. It also has superior emission properties in the conventionally doped 2D- TMDs-based junctions, while the post-growth doped materials-based p-n junctions exhibit better diode characteristics in terms of electrical properties.