2023 QEPrize Winners
PERC Solar Photovoltaic Technology
The 2023 Queen Elizabeth Prize for Engineering is awarded to Martin Green, Andrew Blakers, Aihua Wang and Jianhua Zhao for the invention and development of Passivated Emitter and Rear Cell (PERC) solar photovoltaic technology, which has underpinned recent exponential growth in high performance, low-cost solar electricity.
Over the last 40 years Green and his team’s pioneering work, combined with that of many others, has transformed photovoltaic technology and dramatically reduced costs, with solar now the cheapest source of electricity in most countries.
The photovoltaic effect was first reported by Edmond Becquerel in 1839 and was able to be explained theoretically by Einstein’s 1905 work on the photoelectric effect. The first practical solar photovoltaic cells were developed at Bell Telephone Laboratories in 1954 and became the standard energy source for spacecraft. Commercial production for terrestrial use began in the 1970s, with the efficiency of commercial solar cells reaching 14% by the early 1980s.
The key contribution of this year’s Laureates lies in greatly boosting the energy conversion efficiency. It was believed that 20% efficiency was the practical limit for a single-layer silicon solar cell until papers by Green, Blakers, Wang and Zhao and others theoretically determined the maximum achievable efficiency lay close to 30%, with Green suggesting a higher practical limit of 25%.
In 1983, Green and Blakers at the University of New South Wales produced solar cells with 18% efficiency, surpassing the 16.5% recorded previously. Over the next few years, they published cell results of 19% and 20% efficiency.
In most solar cells, efficiency was limited, among other factors, by photon-generated electrons being lost through recombining with the thick doped silicon layer at the back surface. To overcome this, PERC introduced an additional layer on the back surface that helped prevent recombination and further, reflected unused photons back into the silicon to generate more electrons. The awardees and their colleagues published their first paper on PERC technology in 1989, boasting a record-setting 22.8% efficiency.
Green’s lab at the University of New South Wales held the global record for efficiency for 30 of the 40 years from 1983 to 2023, with Wang and Zhao leading the work which eventually reached Green’s 25% efficiency target.
The awardees opted to publish rather than patent, since commercial uptake seemed remote, freeing PERC technology to be widely adopted. It took two decades of development before PERC technology entered the mainstream. PERC technology is now the most commercially viable silicon solar cell technology for use in solar panels, recently accounting for almost 90% of the global solar cell market.
The shift to zero emissions electricity to replace fossil fuels is capable of eliminating approximately three quarters of current-day global emissions. Harnessing the power of the sun through the use of silicon photovoltaic cells is rapidly increasing, mostly using PERC cells. Solar is providing about half of new-build electricity generation capacity worldwide.
Not only is solar being introduced into major national electricity grids but because of its low cost and easy installation, it is also appearing in microgrids for towns and in farms and dwellings across global low- and middle-income countries.