Cd-free quantum dots (non-Cd QDs) such as InP for red and green as well as ZnSe for blue emission have been investigated intensively as an emitting material for light-emitting diodes (LEDs) due to their potential as an environmentally friendly alternative to Cd-based QDs with promising device performance.
Here, the research efforts on improving the efficiency and stability of Cd-free QD-LED and the remained challenges will be discussed including our current investigations.
Since the inkjet printing technology for patterning of QD layers is essential for the full-colour display applications. We will present the latest results of inkjet printed QD-LED devices and tandem QD-LED structures.
Our broad understanding of the design approach not only on Cd-free QD materials but also on EL devices can provide new opportunities to overcome the remained research issues for the commercialization of QD-LEDs in the next-generation information display market.
Armin Wedel studied Physics at the University of Rostock from 1981 to 1986. In 1992 he received the Ph.D degree in Physics at the University of Potsdam.
From 1986 until 1991 he works as a scientific research assistant at the Institute of Polymer Chemistry of the Academy of Science in Teltow.
Since 1992 he works at the Fraunhofer Institute for Applied Polymer Research in several research positions. He was a member of research group of physically active polymers with the topic of nonlinear optical properties of side-chain polymers and works as a research assistant in the field of OLEDs, OTFTs and OPV.
Now he is responsible for the development of the technology of organic light emitting diodes (OLED) from the layout to the encapsulation and organic photovoltaic in several applications. Since 2009 the new research topic are QDs as a new class of emitting materials in future display and lighting application.
Since 2006 he is head of the Department of Functional Materials and Devices at the Fraunhofer Institute for Applied Polymer Research and Division Director of Functional Polymers.
He holds more than 18 patents, 70 publications in various journals and is on the board of the German Flat Panel Display Forum (DFF e.V.) and the Mid-Europe Chapter of the Society for Information Display (SID) operates. In 2012 he received an award of the Korean Society Display (Korean Information Display Society) for outstanding achievements in the field of synthesis and application of environmentally friendly quantum dots (QD) for display technology.
Fraunhofer IAP develops customer-specific applications in the fields of OLEDs, OPV, OTFT and sensors. The main focus is on synthesis of novel materials with predictable and reproducible properties as well as on device design and manufacture. In a clean room environment several processing techniques are available from spin coating to inkjet printing and high precision slot die coating on a robot controlled S2S manufacturing line with substrate sizes up to 150 x 150 mm². Current issues for the development of OLED, OPV and OTFT go into the design of flexible devices for signage, for security applications and energy harvesting.
