This article focuses on the photo-ageing of polycarbonate and aims to evaluate the impact of light irradiation on the mechanical properties of the material. The properties were investigated using microhardness testing and AFM nano-indentation experiments. The variations in the polycarbonate macromolecular architecture were then determined using AFM nanoscale thermal analyses. Finally, infrared spectroscopy allowed the identification of some chemical changes involved in the changes in the macromolecular structure. The absorption and degradation profiles were studied with UVeVisible and infrared microspectroscopy analyses, respectively. A new reaction pathway, which corresponds to a cross-linking reaction route, was added to the current photo-oxidation mechanism.