Characterization of PVD Lumogen films for wavelength conversion applications

Lumogen Yellow S0790 is a commercial azomethine based pigment and is used for enhancing CCD devices for detecting ultraviolet radiation. In this work we report on the crystal structure and morphology of the raw material, as-deposited and post-annealed films, as well as the influence these have on the subsequent optical properties. Our measurements of physical vapour deposited (PVD) Lumogen films indicate that commercial Lumogen powder is crystalline in its as-received state, with a melting point of 273.3°C and boiling point of 328.6°C. Furthermore, we have found that as-deposited films on room temperature substrates possess an inherent crystalline structure, which has not been reported previously, but also that the material's structure changes into a completely different crystalline form upon annealing for 90 hours at 80°C.