Atip Pengpad, Hanna Radtke, and Andrew Williamson

PhD students working together on a project in the Photon Science Institute

Background

Atip: I was attracted to this role because solar power can have a great impact on many people, so studying it can make a difference for future generations. I chose the University of Manchester because the UoM has a strong background in the research of solar cells.

Hanna: I am thinking about a career in academia, so doing a PhD after my undergrad was the usual way to go. During my undergrad project I grew quantum dots and studied their optical properties. This motivated me to have a deeper look at more complex nanoparticles for solar cells. Having done my undergrad solid state project in surface science my current PhD project matched my interests and background perfectly.

Andrew: Having looked into various PhD research topics across different groups, I was drawn to this role because I would be able to develop a wide range of experimental and analytical skills and participate in an exciting field of research.

Atip: I chose the University of Manchester because it has a strong background in the research of solar cells.

Hanna: I chose the Manchester because of the project! Basically I knew I'd like to do a PhD in the UK and I had a rough idea that I'd like to do a project which has something to do with quantum dots for solar cells, so I looked through all the projects of all UK universities which have a solid state department and this project in Manchester was the most interesting.

Andrew: Having done my undergraduate degree at Manchester University, I already knew that I loved the city and the Physics department, so it was an obvious choice for me to stay. The fact that the research group is fantastic helped too!

Research

Our research involves looking at the chemical composition of nanoparticles called quantum dots. By controlling the size and architecture of these particles their efficiency to absorb sunlight and the efficiency of charge transfer vital for solar cells can be influenced. We are using tunable X-rays (synchrotron radiation) to excite electrons from the particles. These electrons give us information about the elements and their oxidation state within the sample. This allows us to reveal complicated core shell structures and so we can give feedback as to how the nanoparticle design can be improved to get the best efficiency for solar cells.

Most of our work revolves around analysing data taken during our time at synchrotron facilities around Europe. When at a synchrotron, like MAX-LAB in Lund, Sweden, we take shifts and work for 24 hours a day. We spend our time there operating an ultra-high vacuum chamber and scanning our nanoparticles using a technique called depth profiling synchrotron radiation X-ray photoelectron spectroscopy (XPS). When we return from the synchrotron, we sleep for 24 hours, before getting on with our analysis. We usually go to synchrotrons a few times a year.

We all really enjoy going abroad to work in a high-tech synchrotron facility this is always exciting – and getting to work alongside experts from many different areas of research is enlightening. It is interesting to see data being generated in a big metal machine covered in aluminium foil.

Our project is incorporated into a larger project of studying core-shell quantum dots which is spread across several research groups within and even outside the University of Manchester. Being in a large cooperation with others helps to understand results and through comparison of different techniques we develop a wider picture of the materials we are looking at. We hope that the whole project is contributing to a better understanding of the processes in quantum dots. In the research community we obviously present our work in papers and at conferences.

To raise awareness of green energy and our research our research group (Prof. Flavell's group), in most cases in cooperation with other groups from the Photon Science Institute, we take part in exhibitions for school children and the general public, like in the science arena at the “Live from Jodrell Bank” events. We also give talks and carry out experiments in schools.

For our research, team work is very important especially when we are working 24/7 at a synchrotron – the need to coordinate and plan is paramount, particularly for those working the graveyard shift as logical thought can become quite difficult at 5am!

Future

The overall aim is to increase the efficiency of quantum dot based solar cells; so that they can replace the classic silicon based systems. This is a big aim and it would be great if our project turns out to be one of the small steps towards achieving it.

At the moment it the main problems with efficient quantum dots is that they are unstable and in most cases toxic. So a real ‘game-changer’ would be if someone could produce stable, non-toxic nanoparticles which show high quantum yields and good charge carrier transport into underlying substrates.

Atip: When I have completed my PhD I intend to continue doing research and teach at the Khon Kaen University (Thailand).

Hanna: Well it's still some time to go till I finish my PhD and plans might change, but the most likely scenario is that I will take on a post doc position in a related field.

Andrew: I don't have any firm plans at the moment but I do have aspirations to become an elite dog trainer and move to New Zealand. Alternatively I might become a physics teacher.

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