M.Sc Thesis


M.Sc StudentElla Sinai
SubjectSynthesis and Characterization of Color-Tunable Conjugated
Polymer Nanocomposites
DepartmentDepartment of Materials Science and Engineering
Supervisor Full Professors Frey Gitti
Full Thesis text - in Hebrew Full thesis text - Hebrew Version


Abstract

 Luminescence of non-primary colors requires the combination of two or more chromophores that emit simultaneously. However, the observed color of a mixture of light-emitting polymers originates generally only from the lowest band-gap polymer due to efficient energy transfer between the polymers. Isolation of the polymer in an inorganic semiconducting matrix could inhibit energy transfer while still supporting the carrier transport necessary for the operation of light-emitting diodes. Here, we report on the synthesis and characterization of red, green and blue nanocomposites, prepared by intercalating conjugated polymers into the galleries of layered semiconducting SnS2. The nanocomposites structure and properties were studied by XRD, SEM, TGA, optical absorption and photoluminescence. Synthetic parameters, such as initial SnS2 particle size and extent of intercalation time on the intercalation efficiency were investigated. It was found that reducing SnS2 particle size to sub-micron significantly improved intercalation efficiency, while increasing intercalation time above one day had no effect on the intercalation yield. Furthermore, the thermal stability of the composites was studied by measuring the XRD and TGA patterns following a series of heat treatments. Optical characterization by photoluminescence and absorption indicated that the intercalated polymers maintain their optical properties upon intercalation, so that the nanocomposite’s emission spectra are similar to those of the intercalated polymers. Finally, color tunability was achieved by mixing the monochromatic composite powders at controlled mixture compositions. The efficacy of this simple approach for color tunability was demonstrated by fabricating single-layer light-emitting diodes in a variety of non-primary colors.