Job - Postdoctoral fellow Light scattering for white LEDs (24 months)

There is worldwide a strong drive to efficiently generate white light for many applications in lighting. The modern approach is to employ white light emitting diodes (LEDs). These LEDs typically consist of a blue diode combined with luminescent phosphors to convert part of the blue light to the additional colors yellow, green, and red. The phosphors are intentionally made to multiply scatter light to realize longer path lengths. Thus blue light is converted more efficiently which simultaneously allows for reduced device sizes.
The main challenges for white LED technology are that it is difficult to achieve consistent and predictable color and color uniformity, and that white sources tend to have a chromaticity that depends on emission direction (known as halo or color-over-angle). While one may improve color consistency and avoid halo by introducing extra optical components, this approach inevitably leads to undesirable efficiency losses. Hence basic approaches are needed. The difficulty in solving these technological questions is due to the lack of a physical model of the behavior of light in the phosphors. Currently, the transport of light in phosphors is described by ray-tracing models that do not have predictive power and that are based on unphysical parameters. A physical description of multiple scattering of light from first principles is offered by Nanophotonics. However, these theories are so far not yet employed on broadband sources such as white LEDs.
The postdoctoral fellow will devise and perform optical experiments, and interpret results using modern theory. This research project is funded by the Technology Foundation STW. The research is conducted in a group of enthusiastic young people and inspiring colleagues. Part of your research will be performed at Philips Lighting facilities in Eindhoven, and at FOM-Institute Amolf in Amsterdam. We use state-of-the-art optical facilities including tunable ultrafast lasers and advanced photonic materials. Your research initiatives will be strongly appreciated. We also expect a postdoc to supervise PhD and undergraduate students in our group.

You are an enthusiastic scientist with a PhD degree in Physics, Nanotechnology,  Physical Chemistry,  Electrical Engineering or related disciplines, with strong interest in Physics of light and creating new materials.

If you are interested or want to know more about this vacancy, please contact: prof.dr. W.L. Vos, Phone +31 4895388 or by e-mail, w.l.vos@utwente.nl
Dr. A. Mosk, Phone:+31 53 4895392, or by e-mail,  a.p.mosk@utwente.nl.

We offer a very challenging position in an inspiring multidisciplinary and international environment. As a Postdoctoral fellow you will be offered a full-time (38 hours/week) position for two years. In accordance with the Collective Labour Agreement for Dutch Universities, the gross monthly salary starts at 2861,00 euro gross salary depending on experience plus a holiday allowance (8%), an end-year bonus (8.3% of the annual salary) and a number of additional benefits. The University of Twente provides excellent campus facilities, and actively supports professional and personal development.
 

The University of Twente. We stand for life sciences and technology. High tech and human touch. Education and research that matter. New technology which drives change, innovation and progress in society. The University of Twente is the only campus university in the Netherlands; divided over six faculties we provide more than fifty educational programmes. The University of Twente has a strong focus on personal development and talented researchers are given scope for carrying out pioneering research.

Within the TNW Faculty (Faculty of Science & Technology) of the University of Twente some 700 staff members and more than 1100 students are involved in training and research on the interface of chemical technology, applied physics and biomedical technology. Fields of application include sustainable energy, process technology and materials science, nanotechnology and technical medicine. Research, which enjoys a high profile both at home and internationally, has been accommodated in the multidisciplinary research institutes IMPACT, MESA+ and MIRA. The faculty works together intensively with industrial partners and researchers in the Netherlands and abroad and conducts extensive research for external commissioning parties and funders.