Contact Press / Media
Dr. Armin Wedel
Head of department | Functional materials and devices, QD development
Phone +49 331 568-1910
The objective of the work on technology development for organic electronics devices is to realise intelligent systems in life science, automotive, textile and architectural applications, consisting of a combination of OLED, OPV, organic electronics, sensor and energy storage technologies. To this end, prototypical product ideas and production technology concepts will be implemented.
Quantum dots (QD) are a new class of nanomaterials in which the absorption and emission properties can be adjusted in a unique way. We are developing synthesis processes based on cadmium-free starting materials to provide environmentally friendly and RoHS compliant QDs, e.g. based on indium phosphide or zinc selenide, for QD LED and colour filter applications as well as for solar technology. In addition, new processes are being tested to scale up the synthesis of these materials to the gram scale.
We develop technologies to adapt the properties of surfaces - especially those of polymers - to the requirements of an application. We have experience in very different areas. They range from the development of environmentally friendly pretreatment processes for an adhesive metallization to the functionalization of surfaces for use in biological quality control, the food industry and medical diagnostics. In addition, we have a wide range of analytical tools at our disposal to characterise surfaces.
Our module consists of four printed organic thin-film solar cells, each with an area of 15 x 15 cm². The flexibility in form and design makes them particularly attractive for energy-efficient building. Beyond that, there are also almost unlimited possibilities for use. All processes are scalable, so that inexpensive mass production of the modules is possible.
Quantum dots (QDs) are inorganic nanoparticles that have very special properties due to their small size. The luminescence is narrow-banded and can be adjusted over the entire colour spectrum. QDs have a wide range of applications and are used in many areas: as highly efficient light converters or brilliant light sources in displays, as light sources for illumination and as specific markers in sensor technology.
Our specialization are cadmium-free quantum dots, which are less problematic for the environment and humans. These are based on indium and zinc.
We develop quantum dots (QDs) as emitters in displays and light sources. The QDs are directly electrically excited, the light source previously required to excite fluorescence is no longer necessary. Our innovative optoelectronic devices combine the advantages of OLEDs with the outstanding lighting properties of quantum dots: QD LEDs have the uniform light pattern, the paper-thin structure and the efficient operation of an OLED. At the same time, the wavelength of the light is freely adjustable and very narrow-banded.
We develop organic light-emitting diodes (OLEDs) for ambient lighting and signage applications. OLEDs have a uniform luminance over the entire active surface. The result is a clear and distinct luminous image that is easily visible from any viewing angle. For ambient lighting applications, the active surface can have almost any geometrical shape.
Liquid processing is a new trend in the production of OLED displays. According to the current state of the art, OLED materials are still mostly applied by vapor deposition processes. However, much material is lost on shadow masks and other surfaces. With printing processes, on the other hand, the ink can be applied specifically to the active pixel areas. A material efficiency of up to 90 % is possible for an RGB display.
However, high-resolution displays are a challenge for printing processes. The smallest technically realised drop size in piezo-based inkjet printing is approximately 1 pL. This means that RGB displays can be printed at a maximum of 240 ppi. This is sufficient for television sets. For smartphones and microdisplay applications, however, a resolution of at least 500 ppi is required.
In liquid-processed OLEDs, the extremely thin layers are applied by printing technologies. This eliminates the otherwise usual vapor deposition processes. Cost-intensive vacuum systems are not required. Liquid-processed OLEDs are a current trend in the production of displays. Here, the three active dyes (emitters) in red, green and blue are applied in a structured manner by inkjet or ESJET printing. However, all other layers, which are the same for all three dyes, are still applied by vapour deposition.
We are developing OLEDs which can be produced without any vaporisation processes. OLEDs processed in this way still have a lower efficiency than their conventionally produced models. On the other hand, the investment costs are significantly lower, so that even small quantities can be produced economically. Furthermore, the printing processes can be adapted quickly and flexibly to changes in layout and form. Therefore, completely liquid-processed OLEDs are initially interesting for signage and advertising purposes.
With a transparent complex ink, precise circuits of silver can be applied by inkjet printing. The ink is not particle-based, which on the one hand improves printability and on the other hand allows the processing of thinner layers by a lower loading of silver (< 5 %). Thermal curing is carried out at low temperatures (approx. 130 °C), which allows curing not only on glass (right) but also on sensitive surfaces such as foil or paper (left).