Conference Program - LOPE-C 2011

SCIENTIFIC CONF. | THURSDAY-JUNE 30, 2011
Track 4
Novel Inks and Processes (04:30 pm - 06:00 pm) | LOCATION HARMONIE D / LEVEL C2
05:20 pm Quantum dots for hybrid inorganic-organic LED devices: Materials, processes and applications
Dr Armin Wedel,
Fraunhofer Institute for Applied Polymer Research, Germany
The most promising inorganic luminescent nanoparticles are the quantum dots (QDs) based on core-shell semiconductor materials due to their tunable and highly efficient
emission properties as well as their thermal and photochemical stability. Despite the wide research on the synthesis of cadmium selenide/zinc sulfide (CdSe/ZnS) only few
approaches have been attended to achieve fast and large-scale fabrications for industrial applications. The use of QDs as light-emitting materials in OLED (organic
light-emitting diodes) technologies requires highly purified and surface-modified nanomaterials. For the CdSe system, published syntheses procedures were adapted and
optimized in regard to parameters like the type of precursors and stabilizers, their concentration and ratio, the reaction conditions as well as regarding the shell formation. A
facile and fast purification procedure was developed to prepare the QDs for spin-coating techniques. QDs with high quantum yields (>50%) and narrow emission (FWHM <
30 nm) could be fabricated on a multi-gram scale. OLED devices were assembled successfully by spin-coating these QDs to thin films. The main scope of current research
on QDs is the substitution of the inherent toxic cadmium based QDs by more environmentally friendly materials like indium phosphide (InP). First approaches show the
potential of this system although optimal synthesis conditions are less known in literature. In order to receive high-quality materials suitable for OLED devices the synthesis
of InP QDs with narrow band emission as well as high quantum efficiencies are currently under investigation. On the basis of the optimized InP/ZnS synthesis and adapted
surface modification we could fabricate the first hybrid organic inorganic LED device based on non-toxic InP QDs. The multi-layer OLED device could be even assembled
on rigid glass substrates or flexible polymer substrates.
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