Developing highly efficient nanowire solar cells to help meet future global clean energy demands
New research funded at UCL will provide a roadmap for high efficiency and low-cost solar cells of the future. The Leverhulme Trust have just awarded a 3 year Research Project Grant for over £180k for a project titled "High-efficiency GaAsP nanowire solar cells on silicon" to UCL Electronic and Electrical Engineering. The work is to be directed by Professor Huiyun Liu, Professor of Semiconductor Photonics.
The exponential demand for energy is a grand challenge for the future of humanity. Solar energy is arguably, one of the most viable means to meet our clean energy demand. The sun continuously delivers to the earth 120,000 TWs of energy, which dramatically exceeds the world's current rate of energy needs (13 TW). Amazingly, covering just 0.1% of the earth's surface with solar cells of 10% efficiency would satisfy our current global energy requirements. However, the energy currently produced from sunlight remains less than 0.1% of the global energy demand. The major barrier for the large-scale use of solar energy is the high cost and inadequate efficiencies of existing solar cells.
Innovations are needed to harvest incident solar photons with greater efficiency and economic viability.
Silicon-based solar cell modules currently dominate the solar energy market because of their low-cost and long term reliability, but convert only about 8-20% of the available solar energy. Very high efficiencies (>40%) can be obtained using multi-junction cells with several active layers, each absorbing different parts of the solar spectrum, combined with concentrator optics to reduce the amount of expensive compound III-V semiconductor materials, on expensive Ge substrate. However, the III-V materials and Ge substrate needed for such devices are too rare and expensive for broad use.
Professor Liu and his team propose to combine these above two approaches to develop multi-structured III-V semiconductor technology using nanowires, which can yield even higher solar cell efficiency, but use inexpensive silicon substrates. High-performance solar cells will be achieved by the fabrication of defect-free III-V nanowires on silicon substrate, which will exploit the advantages of nanowire's unique growth mechanism - nanowires have a unique strain tolerance that allows unusual material combinations. The UCL engineers aim to combine multi-junction light harvesting with inexpensive substrates that are better suited for high-volume mass-production, to create highly efficient, low-cost solar cells. In addition, nanowires are promising for photovoltaic devices due to several advantages of 1-D nanostructures over thin films, such as (i) increased light trapping, (ii) a direct path for charge transport, and (iii) a greater surface area for light harvesting offered by the geometry of such nanostructures.
Professor Liu has extensive experience in epitaxial material growth and solar cell devices, and is in a strong position to make a considerable international impact in this strategically important field. This research is unique in the UK and the establishment of novel III-V epitaxial material systems and new low-dimensional quantum devices on Si substrates has massive potential if successful.
About Professor Huiyun Liu
In 2007, Professor Liu was awarded the Royal Society University Research Fellowship to develop advanced semiconductor nano-scale materials and devices. Over the past 15 years, he has built a wealth of knowledge, extensive expertise, and an established a track record on the development of the state-of-the-art quantum-dot (QD) and nanowires photonics materials and devices by molecular beam epitaxy. To date, he has co-authored over 250 papers (including Nature Materials, Nature Photonics, Nature Communications, and Nano Letters) with >3200 citations and a h-index of 32, demonstrating the high impact of research that he has led and has been involved in.
About The Leverhulme Trust
The Leverhulme Trust was established by the Will of William Hesketh Lever, the founder of Lever Brothers. Since 1925 the Trust has provided grants and scholarships for research and education. Today, it is one of the largest all-subject providers of research funding in the UK, distributing over £60m a year.