A group of Trinity researchers, led by Professor of Chemistry John Boland were recently awarded a European Research Council (ERC) Proof of Concept grant to the value of €150,000 which will allow them to further develop new nanotechnologies which could revolutionise smart devices and solar panels. Specifically, they work in the field of nanowires. These are infinitesimally small electronic components, on the order of nanometers – billionths of a metre – used in the production of all kinds of digital devices endemic in the modern world. Trinity News sat down with Prof. Boland and Dr. Emmet Sheerin to learn how this research developed over time and where they hope to take it next.
This grant follows five years of research which was driven to a large extent by Dr. Emmet Sheerin who did his PhD under Prof. Boland and who is now a research fellow. During this time, Sheerin worked with Boland on nanowire technology which would essentially allow for complex, transparent conducting materials which had capacities far beyond existing conductors in terms of efficiency and durability. Boland says that during these five years of research (which were also funded by the ERC) the focus of the research changed on several occasions, as the potential applications of their research became more evident over time and new ideas arose.
In the first phase, the research revolved primarily around the development of nanowire networks capable of having a ‘memory’ comparable to connections in the human brain, where efficient and rapid conductivity of signals would be possible by means of artificial junctions between nanowires. It was also in this initial phase that they developed a technique which essentially lays out a template on which the nanowires can naturally align themselves in such a way that seamless always active junctions are formed between each nanowire.
“Existing technologies – used in the touch screens of smart devices and the photovoltaic cells of solar panels – are reliant on glass, which has limitations in its flexibility, durability and weight.”
As their research continued, they made the decision to shift the focus of their research to a previously unexplored application of nanowires, with the same techniques that they had already developed in the first phase. Specifically, they wanted to explore the use of plastic, rather than glass, as their transparent semiconductor. Existing technologies – used in the touch screens of smart devices and the photovoltaic cells of solar panels – are reliant on glass, which has limitations in its flexibility, durability and weight. By choosing to pair inexpensive PET plastic with their nanowire networks, their work sought to bring about an alternative which could challenge the market dominance of the current solutions.
Another important component of their research was the use of aluminium as the chosen conductor in the nanowire networks. Research in nanowires structures had so far been limited primarily to silver, due to it being an excellent conductor and its capacity to form the structures required for nanowires. Silver is however a very expensive and rare metal, especially when compared to aluminium which is the most abundant metal on Earth. Furthermore, despite being quite resistant to corrosion, silver still does corrode and degrade eventually, which aluminium doesn’t. The ease with which aluminium nanowires can be produced on plastic semiconductors is another huge advantage, and Boland says that by coupling these two innovations, the efficiency of the nanowire networks they have created match those consisting of a silver nanowire network and a glass semiconductor.
“Plastic brings with it the advantages of high flexibility, low weight and low cost.”
Although the technology used to produce glass has become increasingly complex, in order to increase durability and even allow some flexibility, there is a limit to how much further we can push it. Plastic brings with it the advantages of high flexibility, low weight and low cost. Despite this, its use as a transparent semiconductor has been very limited due to the structural nature of plastic. Plastics will normally form a series of ridges all along the surface which reduce the amount of light or tactile feedback which pass through the plastic down to the conductor. This characteristic leads to lower efficiency in the nanowires underneath the surface, which are reliant on these signals. It also creates a surface roughness which renders it unappealing for use in touchscreens. Whilst doing their research using plastic as a transparent semiconductor, Sheerin and Boland developed a new, inexpensive planarisation technique which removes the roughness and leaves a smooth surface which is comparable to polished glass.
The other problem with plastic is that it is not as airtight as glass, and so any conductors paired with it are prone to corrosion over time, due to exposure to oxygen. When deposited as a nanowire forming structure, aluminium naturally forms aluminium oxide (Al2O3) on its surface, a thick compound which prevents further corrosion and so pairing it with a plastic semiconductor was the obvious solution to this particular problem. Overcoming the limitations which have so far plagued plastic will likely prove to be an important step in the next phase of technological advancements in devices which have until now relied on long-established materials like glass and silver.
Whereas silver has been used in developing nanowire technologies, almost all conventional smart devices use Indium Tin Oxide (ITO) as a conductor for their touch screen technologies as it is easy to mass produce. However, this alloy is quite rare compared to a cheap, plentiful metal such as aluminium, so the benefits of developing these new technologies are clear. ITO is also deposited as a film rather than a nanowire and so it is relatively inflexible.
As Sheerin and Boland enter the next phase of this research they reflect on the significant changes in direction which emerged as the project matured and the applications of the work they were doing became more apparent. What started as research in the development of an artificial neural network capable of machine learning, evolved over time to focus primarily on the applications of nanowire networks coupled with transparent plastic semiconductors in the development of novel, advanced technologies.
“their work could, quite literally, shape the technology of tomorrow if realised.”
From the production of vehicles and construction of buildings whose surfaces incorporate flexible solar panels to the development of flexible smart devices which are more durable and cheaper to produce, their work could, quite literally, shape the technology of tomorrow if realised. While many grants are given over the course of two or three years, Boland says that by awarding five-year grants to fund research such as this, the ERC gives a high degree of freedom to its scientists to develop the various aspects of their research over time in line with those aspects which are likely to benefit society the most.
With the strong foundation they have built in the area of nanowire technology, Sheerin and Boland now hope to apply their findings to producing prototypes which incorporate these new technologies. Boland emphasises that entering this phase in research and development would be impossible were it not for the diverse skill set present in the chemistry research group CRANN and also the Science Foundation Ireland funded AMBER research group Their workforces consist not only of researchers, but also outreach staff who establish vital connections with companies who would be interested in partnering up to develop such prototypes. Legal experts also play an important role since they provide much needed assistance to the scientists in filing patents so that technologies and techniques are not stolen.
The success of this research so far is testament to the advancements which can be made when scientists are given sufficient freedom and funding. Perhaps in the not so distant future we will see the fruits of their labour implemented in everyday technologies.
