This paper demonstrated Multi-stages peel test method to evaluate the interfacial adhesion strength between brittle thin film and polymer substrate for flexible optoelectronic devices. The mechanical properties of polymer substrate are strongly influenced by UV irradiation. Therefore, it is considered that the UV irradiation also affects the interfacial adhesion strength between ceramic thin film and polymer substrate. The interfacial adhesion strength was measured by Multi-stages peel test. The results show that the interfacial strength depends on the peeling angle and UV irradiation makes the interfacial adhesion weaker. In-situ observations under tensile test of PET/ITO film were also carried out to investigate the fracture process of brittle thin film under tensile loading. The results show that the crack initiation on brittle thin film decreased after UV irradiation. It is considered that since the interface was damaged due to UV irradiation and the rigidity of interface decreased, the shear stress at the interface between PET/ITO interfaces cannot be high enough to make new cracks.
