In this work, we report on p-Phenylenediamine (PPD) functionalized reduced graphene oxide (rG0)/Si hybrid-structure designed for UV photodetector applications (PD). The hybrid-structure was characterized by using Fourier Transform-infrared spectroscopy, X-ray photoelectron spectroscopy to confirm the formation of nano-hybrid structure and the experimental results confirmed the covalent bond between rGO and PPD. The diode parameters such as barrier height, series resistance, and ideality factor were estimated for both PPD functionalized rGO (PrGO)/Si and rGO/Si heterostructure by using I-V characteristics. The time-resolved photocurrent spectroscopy used to examine the photoresponse properties of both PrGO/Si and rGO/Si samples with UV light (lambda = 382 nm). The experimental results showed that PrGO/Si exhibited significant UV photoresponse than that of rGO/Si PD. The PrGO/Si heterostructure device exhibited photoresponsivity of 1.4 x 10(-3) A/W, which is 15 times higher than rGO/Si. The high photoresponse was attributed to the synergistic effects originated from the charge transfer between PPD and rGO. The results proved that PrGO is a promising material for high response photodetector applications.