Solid state lighting based on large scale thin film devices are considered to be promising for future applications. We suggest to use stable and tunable composite thin film formed from small (nanosized) particle of lower direct bandgap embedded into wide bandgap transport layers e. g. of ZnO or ZnS and/or organic polymer (oligomer) semiconductors. Various fabrication processes wil be used such as, wet from formulated composite inks, sol-gel as well as vacuum based deposition in order to vary the size, distribution and percentage of clusters embedded into the transport matrix.

The alignment of energy levels (valence band offset, conduction band offset) will be investigated using composite films but also layer-on-layer type model systems to determine the energetic conditions of electron/hole transfer. The optical properties will be investigated by luminescence and electrolumincescence experiments. The structural stability of the thin films will be investigated with various scattering (SAXS, WAXS, GISAXS and SANS) and microscopy techniques (TEM, SEM, AFM, STM).

After the proof of concept the optical performance shall be systematically improved and the possibility of using clusters emitting at different wavelengths will be tested. Finally, demonstrator devices shall be developed which shall allow to decide on the technological perspectives of the given approach.

project partners:

TUD - Surface Science: vacuum technique expertise; deposition of hybrid materials, structural characterization, expertise in surface science

UB1 - LCPO: Polymer synthesis and their formulation into composite printable inks, sol gel based synthesis of composites, structural characterisation of the thin films

MERCK Darmstadt Germany