In our last inspirational scientist blog, Charlie Barty-King, PhD student at the University of Cambridge, described his work with hydroxypropyl cellulose. In the next instalment of the series Alex Gillett, a postdoctoral researcher in the Optoelectronics group at the University of Cambridge, describes his research on improving the efficiency of polymer solar panels, compared with traditional silicon. Polymer solar panels have the potential to provide greener energy than silicon as their production requires much lower temperatures and consequently has a lower carbon footprint. Read on to find out how to combat global warming with polymer solar panels and get Alex’s advice on working in science.
A warming planet
In recent years, there has been an awakening in society about the impact of global warming on our planet. We are now beginning to see the impact of higher temperatures in our everyday lives, from rising sea levels to more extreme weather events. Ultimately, global warming is being driven by our ever-increasing demand for energy, needed to power our modern lifestyles. However, it is not necessarily our demand for energy that threatens our survival as a species, but rather where we get this energy from. The huge increases in living standards enjoyed by some, but not all, of the world’s population is derived from fossil fuels, such as oil and gas. By burning fossil fuels to create the energy on which we are so dependent, we are effectively releasing carbon dioxide that has been trapped deep in the earth’s crust for millions of years back into the atmosphere. The increased levels of carbon dioxide in the air that we breathe then traps more heat, ultimately resulting in global warming.
Generating energy without pollution
To combat global warming, scientists around the world have been searching for less polluting ways to generate energy. This often relies on extracting energy from natural phenomena, such as the wind and the tide. The area that I work in involves capturing energy from the sun; there is enough energy from the sun hitting the earth every hour to power all of humanity for one year! Therefore, exploiting this abundant and limitless energy source will play a key role in the transition away from fossil fuels.
Converting sunlight into electricity
The most common way of converting sunlight into a useful form of energy (electricity) is through a solar panel. These are the blue-black rectangle slabs that you see mounted on top of buildings, or even in large scale ‘solar farms’ scattered throughout the countryside. The distinctive colour of these solar panels is because they are made from silicon; virtually every solar panel you will see uses this element. This is because silicon is cheap and widely available. However, for a solar panel to operate efficiently, the silicon needs to be very pure. To achieve this, very high temperatures are required: over 1000 oC! This creates a conundrum: whilst solar panels generate electricity without pollution, a significant amount of energy is required to obtain the very high temperatures needed for their production. This energy almost always comes from fossil fuels, which releases significant amounts of carbon dioxide into the atmosphere. Therefore, silicon solar panels are not as ‘green’ as they seem!
A new type of solar panel
My research focuses on next-generation materials that can be used in solar panels. A promising type of materials is ‘polymers’; effectively fancy versions of the plastics used to make shopping bags. Polymer solar panels show great promise as their production requires much lower temperatures than silicon (less than 100 oC). As a result, the amount of carbon dioxide created per ‘kilowatt hour’ (a common unit of energy) is only about 5-7 grams for polymers; much better than the 50 grams for silicon. However, a key issue for polymers is that they are generally less efficient in converting sunlight into electricity than silicon. A typical silicon solar panel that you might see on your neighbour’s roof can convert about 20% of the sun’s energy into electricity; for a commercial polymer solar panel, this is currently only about 10%. Whilst these numbers may sound low, the theoretical maximum efficiency of a solar panel is only about 30%! However, the lower efficiency of polymers is a key factor now limiting their widespread use. Therefore, the aim of my research is to improve the efficiency of polymer solar panels so that they are more commercially competitive with silicon.
Why Science?
Science was not something I specifically intended to do as a career; it was originally just a topic that I did well at in school, probably because I enjoyed it more than the other subjects. As a result, I decided to pursue an undergraduate degree in chemistry. However, my interest in polymer solar panels didn’t begin until I did an undergraduate research placement in a group that worked on these materials. As I enjoyed this experience so much, I decided to do an industrial placement year as part of my undergraduate degree in a company that was trying to develop polymer solar panels. The experienced gained from these roles allowed me to obtain funding to do my PhD in Cambridge on this topic, which has ultimately led me to the position I am in today: doing science as a career. I am quite fortunate to have a lot of freedom in determining my own research direction, which is something I particularly enjoy. Having a job where you are free to investigate those things that interest you most is very rewarding.
How to become a scientist
The process of becoming a scientist begins at school, even though you might not realise it at the time. As well as working hard (most undergraduate science degrees require quite high grades for entry), it is also important to choose the correct subjects to study. For your A-levels, IB, or equivalent, studying those subjects out of physics, chemistry, and biology, that interest you most is the first step. It is also often beneficial to study more than one of these subjects; physics and chemistry make a good pairing, as well as chemistry and biology (or even all three!). As well as pure science subjects, maths (and further maths) is also an important choice. Science degrees contain a significant mathematical content, so being familiar with maths is very beneficial; many universities will often insist that you have a good grade in maths, as well as the other science subjects, for admission. Once you are accepted onto an undergraduate science course, take every opportunity to explore the exciting science taking place around you. As well as teaching, universities also conduct cutting-edge scientific research; there will often be the opportunity to get involved with this though summer research placements or research projects in your final year of study. Getting hands-on experience in the lab is also very beneficial in securing a job as a scientist after your degree, or even a PhD position. A PhD involves 3-4 years of working as a junior scientific researcher at a university, during which time you will gain practical skills for performing scientific experiments and develop your scientific mind. Ultimately, a PhD is a necessary requirement to becoming an academic (a university-based scientific researcher) and is also highly desirable qualification for jobs in scientific industries.
Alex received his PhD in 2019 under the supervision of Professor Sir Richard Friend in the Optoelectronics group at the University of Cambridge. He is now currently a postdoctoral researcher in the same group and a by-fellow of Churchill College. His research interests include using laser spectroscopy techniques to understand and improve polymer solar cells. Previously, he also worked at Merck KGaA, where he studied the degradation mechanisms of polymer solar cells.
