Fraunhofer Institute for Applied Polymer Research

The Fraunhofer IAP is active in organic electronic research ranging from synthesis of novel materials with improved optical properties to device design and manufacture. Key research areas are OLEDs, OTFT, OPV, sensors, and actuators, Quantum Dots (QDs) and the printing technology ESJET.

Quantum dots (QDs) represent the latest generation of hybrid inorganic-organic nanomaterials. They form a triad of inorganic nanotechnology, organic semiconductor technology and solution-based processability. The emission properties of these inorganic, luminescent nanoparticles are controlled by the particle size. Fraunhofer IAP has developed several procedures for the synthesis and modification of QDs to provide very stable indium phosphide (InP) QDs covering a wide spectral range from green to red with a high quantum yield, low Full Width of Half Maximum (FWHM) and high stability in organic solvents and in polymer materials or resists.

Developing the high-performance QD-LEDs based on InP-based QDs is quite important to bring QLEDs into the future market. The researchers  investigated the performance of inverted QD-LEDs fabricated with synthesized multi-shell InP/ZnSe/ZnS QDs and ZnO nanoparticles for pixel areas down to 20 µm.

Solution processability is achieved with electrostatic (ESJET) or electrohydrodynamic jetting (EHDJET), a new technology for printing structures with very high resolution and aspect ratio. ESJET or EHDJET lowers the resolution limit for digital printing to 1 µm. It is a method of liquid processing under ambient conditions and can thus replace more expensive microfabrication technologies. One of many possible examples is high-resolution OLED and QD-LED smartphone displays.