Developing improved ways to manufacture quantum dots

A Keele researcher has been awarded a prestigious grant to develop ways of improving the manufacture of an advanced nanoscale technology – quantum dots – which has a huge range of applications, to make it more accessible and available for researchers and electronics manufacturers.

Dr Peter Matthews, Research Fellow in Energy and Sustainability, has received a £221,717 grant from the Engineering and Physical Sciences Research Council (EPSRC - grant reference EP/V043412/1) for a project to develop ways of improving the manufacture of quantum dots, a nanoscale technology which can be utilised in a variety of ways, including everything from solar panels and TV screens, to testing for infections and detecting drug levels.

Quantum dots (QDs) are fragments of semiconductors that absorb and emit different colours of light depending on their size. They are over a million times smaller than a golf ball, and they can be very difficult to manufacture.

In an ideal manufacturing scenario, all the QDs created would be identical in size, representing perfect quality control, but this is very difficult to achieve in practice due to the way they are currently created.

This involves two materials reacting to form a central point, or nucleus, around which the QD grows in a matter of minutes. However, if the mixing of the two materials is not even, then these nuclei form at different times and so the growth period of the QDs lasts for different lengths of time, resulting in different sizes.

Researchers in a laboratory can control this process relatively easily, but on a practical industrial scale it extremely hard to achieve instantaneous mixing, meaning the uptake of these materials has been low despite their amazing potential.

To combat this, Dr Matthews and his colleagues will develop a new synthetic route that eliminates the need to form nuclei, by preparing these in advance – removing the need for instantaneous mixing. This will enable the researchers to have perfect quality control over the size of the quantum dots that they produce.

They will prepare compounds consisting of a cluster of the elements that make up the quantum dot and optimise the route from these cluster nuclei to QDs by controlling the growth.

Dr Matthews said: “For quantum dots it can be very hard to determine the exact position of each atom, without using an extremely expensive high-powered electron microscope, of which there are only a few worldwide.

“However, we can take advantage of routine molecular techniques to determine the exact atomic positions of the cluster’s constituents, such as any additives or their surfaces. In this second part of the project, we will develop so-called molecular models of the QDs, to allow the rationale design of future materials and empower more researchers, facilitating the future development of QDs.

“I’m very excited to begin tackling this project at Keele and to start producing some really useful results that will benefit industry and research partners alike.”