Electroluminescence and photoluminescence of UV-aged poly(ethylene naphthalate) films

Changes in the optical and electrical properties of poly(ethylene 2,6-naphthalate) films aged under controlled UV irradiation are evaluated. Photoluminescence, conduction measurements and electroluminescence have been carried out in reference and aged materials. The fluorescence yield significantly decreased in aged materials, and new bands that are characteristic of the aging process appeared. The electroluminescence yield also dramatically decreased in UV-aged materials and so did the external current under DC field. This was confirmed by imaging the electroluminescence of a sample partly exposed to UVs. Some new information is brought regarding field-induced aging of the material.