Porous silicon is very important for integrated technology due to its many superior properties such as its suitability for mass production, easy and controlled production, adjustable electrical and optical properties. Semiconductors with metal oxides such as indium oxide, indium tin oxide, tin oxide and zinc oxide are highly preferred in optical devices. Among these metal oxides, zinc oxide is especially preferred for photodetectors due to its stable crystal structure and large exciton binding energy of 60 meV. Researchers have carried out research on photodetectors with porous silicon-zinc oxide heterojunction structure. The importance of stable operation of the devices has been emphasised. For this reason, in this study, a porous silicon-based-zinc oxide heterojunction structure suitable for photodetector production was formed and the effect of aging of zinc oxide was investigated depending on time. As a result of the investigation, it was observed that the intensity decreased approximately 2.5 times at the end of 365 days due to the aging of zinc oxide. In addition, UV spectroscopy measurements were taken to investigate the optical properties that will affect its operation as a photodetector. Since the PS-ZnO heterojunction works as a detector in the UV region, the absorption and reflectivity of the PS-ZnO heterojunction were investigated especially in the UV region. As a result of the measurements, it was observed that aging decreases the absorption and increases the reflectance. All these findings underscore the negative impact of aging on photodetector performance.