PhD student position in materials physics

Project description
Phosphor-converted white light emitting diodes (LEDs) based on a blue LED coated with yellow and red phosphors, or a near ultraviolet LED coated with red, green, and blue phosphors have become mainstream for many lighting applications. Commercially used LED phosphors contain rare-earth elements, but since rare-earth elements belong to the EU critical raw materials, new lighting solutions are urgently needed.

Lead (Pb) based halide perovskites are currently attracting large interest as LED phosphors free from rare-earth elements, but the toxic lead is a big problem for applications. The search for lead-free variants has recently led to the discovery of luminescence in, so called, halide double perovskites of the type A2BB’X6 (see e.g., J. Luo et al., Nature 563 (2018) 541) (A = K+, Rb+, Cs+; B = Li+, Na+, K+; B’ = Ga3+, In3+, Sb3+ and X = F-, Cl-, Br-, I-), which, besides being composed of abundant and safe elements, show broadband (white) luminescence. This latter feature is a very rare and attractive property for applications in LEDs, since it allows creating white LEDs based on a single phosphor. However, a strong reduction of the emission intensity upon increasing temperature, known as thermal quenching of luminescence, hinders the development of a white LED technology based on these materials. Developing thermally stable halide double perovskites depends on a mechanistic understanding of the light emission, but this is lacking. This PhD student project seeks to contribute to this knowledge gap, by unravelling the mechanism of thermal quenching of luminescence in halide double perovskites. The acquired new basic understanding will not only be of considerable fundamental interest but will be used as feedback into materials synthesis programs in order to develop new halide double perovskite phosphors with improved properties. 

The project is experimental in nature and focuses on physical and optical characterization of lead-free double halide perovskites. The techniques include physical and optical characterization techniques (photoluminescence techniques, IR/Raman spectroscopy, x-ray diffraction) at Chalmers, and techniques at international large-scale photon sources around the world (e.g. time-resolved diffraction and x-ray absorption spectroscopy). For this project, we will have a particularly strong collaboration with the Extreme Light Infrastructure Beamlines in Prague, Czech Republic. 

The recruitment is connected to the Wallenberg Initiative Materials Science for Sustainability. WISE, funded by the Knut and Alice Wallenberg Foundation, is the largest-ever investment in materials science in Sweden and will encompass major efforts at Sweden’s foremost universities over the course of 10 years. The vision is a sustainable future through materials science. All early-stage researchers recruited into the WISE program will be part of the WISE Graduate School, an ambitious nationwide program of seminars, courses, research visits, and other activities to promote a strong multi-disciplinary and international network between PhD students, postdocs, researchers, and industry.

Information about the division and the department
The project will be conducted within the research group of Prof. Maths Karlsson at the Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Sweden. The group focuses on characterization of fundamental key aspects of structure and dynamics in “functional” materials, with a view towards their implementation in energy-relevant technologies, such as light-emitting diodes, solar cells, batteries and fuel cells. The primary tools to this end involve the use and development of techniques at large-scale neutron and photon sources, vibrational spectroscopy, optical techniques, and computer modelling.

Major responsibilities
Your major responsibility will be to carry out the PhD project, as described briefly above. You are expected to develop your own scientific concepts and communicate the results of your research in a wide context, e.g., through meetings, seminars, national and international conferences, and in the form of informal reports, and peer-reviewed publications. As a PhD student, you will as well take courses corresponding to 60 ECTS and be involved in teaching on the undergraduate level corresponding to about 10% of your time.

Qualifications
To qualify as a PhD student, you must have a master’s level degree corresponding to at least 240 ECTS in a relevant field such as physics, materials science, or chemistry. The nature of this research project falls with the area of materials/optical physics. To be successful, you need to be highly motivated and have high analytical and communication skills. Given the strong international nature of the project, and the collaboration with several research groups and facilities around the world, you also need a flexible approach and enjoy traveling. Experience in advanced optical techniques, and in computer programming (which will be important for data analysis), is an asset.

The position requires sound verbal and written communication skills in English. If Swedish is not your native language, Chalmers offers Swedish courses.

Contract terms
Full-time temporary employment. The position is limited to a maximum of five years.

We offer
Chalmers offers a cultivating and inspiring working environment in the coastal city of Gothenburg. 
Read more about working at Chalmers and our benefits for employees.

Chalmers aims to actively improve our gender balance. We work broadly with equality projects, for example the GENIE Initiative on gender equality for excellence. Equality and diversity are substantial foundations in all activities at Chalmers.

Application deadline: 31-03-23

For questions, please contact:
Maths Karlsson, Department of Chemistry and Chemical Engineering, Chalmers University of Technology
E-mail: maths.karlsson@chalmers.se
Phone: +46 31 772 6770


*** Chalmers declines to consider all offers of further announcement publishing or other types of support for the recruiting process in connection with this position. ***