Transparent and light-emitting epoxy nanocomposites containing ZnO quantum dots as encapsulating materials for solid state lighting

Polymer nanocomposites are usually made by incorporating dried narroparticles into polymer matrices. This would easily lead to aggregation of nanoparticles and then would readily bring about opaqueness for narrocomposites based on functionally transparent polymers. In this work, preparation of highly transparent ZnO quantum dots (ZnO-QDs)/epoxy nanocomposites that can emit intense luminescence was reported for the first time by uniformly dispersing ZnO quantum dots in a transparent epoxy resin via a direct dispersion method. The direct dispersion of ZnO quantum dots without drying in the epoxy matrix could effectively avoid aggregation of fine quantum dots and showed a good dispersity of ZnO-QDs in the epoxy matrix. Such materials showed a high transparency in the visible region and exited a broad emission spectrum peaked at 442 nm. On the other hand, in traditional solid state lighting emission diodes, semiconductor quantum dots are used as phosphors that are attached to the die of the lighting emission diode (LED) lamps for emitting luminescence. In this work, the as-prepared ZnO-QDs/epoxy nanocomposites were successfully employed as packaging materials for solid state lighting emission diodes in which conventional phosphors are not required while the nanocomposite encapsulating materials are responsible for emitting luminescence and thus the encapsulated LED lamps have an innovative structure. Consequently, the as-prepared ZnO-QDs/epoxy nanocomposites are promising for use as novel encapsulating materials in LED technology due to the much simplified encapsulating process.