A woman in science and engineering can improve the world and enjoy doing it
In 2010, Dr Kylie Catchpole’s work on nanophotonic light trapping was listed as one of MIT Technology Review’s ‘10 most important emerging technologies’. In 2011 she was an episode winner on ABC television’s New Inventors. Her work has been featured in the news sections of Science magazine and The Economist, and she has published over 60 papers which have been cited over 1000 times to date.
These achievements highlight what Kylie loves most about science – it is “really important” and it is also “a lot of fun”.
Kylie was always interested in science – physics in particular – and she was also interested in environmental issues. “Solar cells,” she says, “seemed the perfect combination.” She describes the aim of her research very simply, but with tremendous enthusiasm, as “better, cheaper solar power”.
“My research is basically about putting tiny particles of silver on the surface of solar cells to make the cells work better. Even the most efficient solar cells today reflect some light, so energy is lost. These particles act as antennas to transmit the light directly inside the cell. The light can then bounce back and forth inside the cell, which increases the chance that the light will be absorbed. This increases the amount of energy the cell can produce. Depending on the cell design, we can produce up to double the electrical current.”
Importantly, Kylie’s research can be used on thin solar cells. Thin cells are much cheaper than conventional cells because they use less silicon. “The thickness of a thin-film silicon solar cell is only one or two micrometres compared with 200 micrometres for a conventional wafer cell”, she explains. “Since silicon is the highest cost in a solar cell, a thin cell can dramatically reduce your material costs.”
However, while thin-film silicon solar cells are cheaper than conventional cells, they are also much less efficient. “When you decrease the thickness that much, you also decrease the absorption of light”, says Kylie. “The improvement in efficiency and decrease in material cost we have achieved in our cells could help make solar power more competitive with fossil fuels.”
When Kylie says science is “really important” she is not overstating the case.
Kylie is Canberra-born and did her undergraduate physics degree at the ANU, winning a University Medal. She also earned her PhD from ANU. Following that she was a post-doctoral fellow at the University of New South Wales (UNSW) and the FOM Institute for Atomic and Molecular Physics in Amsterdam where she had the opportunity to work with some world-leading researchers.
Amsterdam was a professionally and personally rewarding experience. “It was great to see how another city worked,” she explains. “Amsterdam is an amazing place and a tribute to what planning can achieve – it has a population 32 times larger than Canberra, but it feels much less crowded than Sydney. There are dedicated lanes for bikes, trams and buses, lots of green space.”
In a move that feels like “coming full circle” Kylie is now back in Canberra as an Australian Research Council Research Fellow and she currently leads the nanostructures for photovoltaics group at the Centre for Sustainable Energy Systems in the ANU College of Engineering and Computer Science.
It was her beginnings in physics that gave Kylie the ideas and insights into the science of solar cells which has supported her breakthrough developments. Her understanding of plasmons – density waves of electrons created when light hits the surface of a metal under precise circumstances – has been particularly useful in solar cell development.
Kylie first came across plasmonics when investigating the light wavelength absorption of different metals and she started to think about how it could be applied in solar engineering. The tiny nanoparticles Kylie places on the top of silicon cells produce plasmons which direct light into the cells, which is the antenna effect that makes the cells so efficient.
Almost every scientific development or breakthrough is, like this one, a mix of ideas from different fields but Kylie is quick to point out that every piece of research described as a “breakthrough” really takes many years of research and testing.
So following her “breakthrough” there is now the slow process of developing knowledge about designing structures at a very small scale – from one to 100 nanometres – where tiny changes can have large impacts. Slow as it is, Kylie believes that this current research will produce answers in two years – and the main question is, says Kylie, “is it a cost-effective process?”
Solar research is a growing area at ANU. The Centre for Sustainable Energy Systems is one of the largest in Australia with around 80 researchers and the group works with UNSW and overseas research groups and industry. “Sadly,” says Kylie, “in Australia we do not have any solar manufacturers available for collaboration. We are working with a number of Asian companies – for example we are working with the third largest solar company in the world which is in China.”
While it would be beneficial in so many ways to have more of a solar industry in Australia, Kylie points out that Australian intellectual property is contributing to global development in the whole solar power field. “This will have returns for Australia in terms of rewards for any commercial deals that are struck. It will also have returns in that we will have new solar technology available for households and industry here.”
Solar panels on house roofs are becoming a relatively common sight. Prices of solar modules have dropped markedly in the last few years. This in turn has increased demand and achieved economies of scale that are pushing prices down further. Even cheaper solar power requires a reduction in the cost of materials or an increase their efficiency.
Kylie’s research aims to do both. “Thin solar cells use less materials, and our methods are also improving their efficiency. We are also looking into ways to make the manufacturing of these more efficient cells cheaper.”
The process she uses for depositing the particles is simple and robust. Metal particles are formed on a solar cell close to the end of the standard solar cell fabrication sequence. Starting with the silicon cell, an oxide is grown on the surface in an oxygen furnace at high temperature. The metal nanoparticles are then deposited on the thin-film silicon cells by vacuum evaporation. This process initially involves evaporating a thin silver film onto the cell surface and then heating the sample to 200°C. This creates roughly evenly sized, evenly distributed particles on the solar cell surface. This process could easily be scaled up for manufacturing.
In Australia solar power is already competitive with the retail price of electricity and this is one of the first countries in the world where this has happened. “It will not be long,” says Kylie, “before Australia will be the first country in the world where solar power is competitive with the wholesale price of electricity.”
Outside the university Kylie enjoys spending time with her family especially when they can get out into the bush in and around Canberra. And she is hoping to do some more travelling now that her children are getting older.
Kylie admits that it is a challenge juggling a family and a research career but she has also found it very helpful. “It has enlarged my perspective,” she says, “I still work as hard as I did before having children, but I worry less about my research.”
The other challenge Kylie has faced is being a woman in science. Statistics about the low numbers of women in science continually highlight the obstacles. “I paid attention to them for a while,” says Kylie, “but I found them too depressing, so my solution to that was to stop reading them.
“I don't think there is intentional bias against women but I do think that there is unintentional bias. For example, there was a study from Sweden that found that papers are judged more harshly if reviewers know the author is a woman than if they don’t know. Since then, I have always used my initials rather than first name on my papers. Also many prizes have age-based limits, which can unintentionally discriminate against women who take time off to have children.”
Despite the challenges and obstacles, Kylie would encourage women to consider going into science or engineering.
“There are lots of very exciting ways to make an important contribution to society in these fields. You also have a tremendous amount of freedom to shape your work to the way you want it to be. Basically you get to do something that’s really important and is also a lot of fun. It’s true that jobs in this area can be insecure, but with these types of skills there will always be plenty of employment opportunities.”