In this article, the effect of different substrate material on characteristics are analyzed for sensing application using photonic crystal fibers (PCF). The proposed quasi cladding slotted core Q-PCF have been investigated over wider frequency spectrum ranging from 0.7 THz to 2.5 THz by utilizing various background materials such as Polytetrafluoroethylene (PTFE), Polypropylene (PP), Topas and Zeonex. The investigation shows that the changes of background material strongly affects PCFs properties like sensitivity, core power fraction, confinement loss (CL) and effective material loss (EML). The investigation also reveals that background material with lower refractive index (RI) provides higher sensing response. PTFE is found to be supreme in communication and sensing application for the proposed Q-PCF. Additionally, different PCF characteristics related to different background materials have been studied explicitly.