Karl Jonas Riisnaes, The 1966 PhD Scholar

Postgraduate Researcher, EPSRC Centre for Doctoral Training in Metamaterials (XM2)

Recap and background

I am writing to give an update on my research which is kindly supported by The 1966 Scholarship. I started my research into metamaterials at the University of Exeter in September 2018. I feel like I have now found my place among my fellow researchers in the cohort and find the benefits of being in an open and supportive community inspiring and exhilarating. As part of my doctoral training I have also been attending courses in quantum mechanics which I have found to be of much use in my self-study of relevant journal papers and condensed matter physics.

Project overview

My research is on the development of perovskite based electrically induced lasers, to demonstrate an electrically driven hybrid graphene and perovskite laser by harvesting the unique synergy of state-of-the-art developments on atomically thin light emitting diodes and lasers, and the novel atomically thin electrically conductive graphene materials.

- Establish and investigate the viability of transportation and storage of Organo-Halide Perovskite Crystals from our collaborators in Italy to our facilities in Exeter.

- Examine methods of device fabrication based on Organo-Halide Perovskite Crystals

- Crystal exfoliation and transfer to Silicon substrates to obtain few layer crystals for device manufacturing

- Submission of 6 month report and mini Viva

- Electrical contact deposition on crystals though orthogonal electron beam lithography

- Fabrication and measurement of perovskite based Photo transistor

- Light emitting diode

- Electrically induced lasing

Research progress to date

So far I have worked out an effective way of transporting and storing the perovskite crystals so they can be used in research for at least 3 months. In addition, through searching literature and our facilities, I have identified electron beam lithography as the necessary method of fabrication.

I am currently experimenting and working out a method for electrical contact deposition on the crystal through the use of electron beam lithography (EBL). EBL will allow us to deposit nano-meter size electrical contacts on top of the crystals. This is an important step in the research on the organo-halide perovskite as traditionally EBL has not been a viable method for electrical contact deposition. EBL uses solvents detrimental to the perovskite crystal in the "development" stage and "lift off" stage. Hence, the research has been focused on finding solvents compatible with the process steps and with the crystal. I'm now close to achieving the first device with electrical contacts using Chlorobenzene as a process solvent in EBL. With the devices made, we will make electrical measurements on the crystal and start the process of developing the first light emitting devices.

Through the experiments carried out to develop a method to deposit electrical contacts I have had to learn how to use several fabrication tools such as an EBL system for patterning PMMA resist and a thermal evaporator for metal deposition. To characterise the state of the crystals I have also had to use a Laser system to look at the specific photoluminescence spectrum associated with this particular hybrid perovskite.

Recently I handed in a report on my work over the last 6 months, which the content of, I have had to defend in a mini-viva. Although I am still waiting for the feedback, my general feeling and indications from my assessors is that the both the report and the viva showed good research and good knowledge of the subject.

Impact of your support

I would like to specify my appreciation and gratitude for the support this scholarship provides in my day to day research. Financially it gives me the opportunity to focus on my research rather than having to take up part time work to make ends meet. I believe good research is hard to achieve unless you have energy and time available for it - it feels like this scholarship provides just that. I look forward to keeping you updated on my progress.