Field enhancement in photovoltaic devices across different length scales

Lead Research Organisation: University of Cambridge
Department Name: Physics

Abstract

Ultra-thin III-V photovoltaics are an emerging device concept offering a light-weight form factor with unprecedented radiation tolerance, as well as fundamental solar energy conversion efficiency enhancement. Thin III-V devices (~1 m) are a commercialized technology however, the ultra-thin regime (an order of magnitude thinner) is relatively undeveloped. It was recently demonstrated that this ultra-thin regime exhibits intrinsic radiation tolerance[1]. Furthermore the ultra-thin geometry enables strong E-field localization which leads to high carrier density and, in theory, corresponding
voltage enhancement. This effect has been considered from a theoretically perspective [2] but never
experimentally demonstrated.
This project will focus on design and simulation, fabrication and characterization of photovoltaic
devices across different length scales. Far-field scattering structures will be employed to achieve full
solar absorption in PV films ~100 nm thick, while near-field plasmonic effects will be exploited to
reduce device thickness by a further order of magnitude (~10 nm). The thinnest geometries offer the
greatest potential for field enhancement but are also the most technologically challenging. Possible
embodiments are illustrated below. III-V films are used because of their relevance to space power
applications but also to provide a radiatively limited system to probe the limits of field enhancement
in photovoltaic devices.

Planned Impact

Our main impacts will be:
- a new generation of interdisciplinary nano researchers with expertise across science and innovation
- development of new nanotechnologies, and their translation into companies
- strategic developments in four key areas: Energy Materials, Sustainable NanoMaterials, Nano-Bio Technologies, and NanoElectronics/Photonics
- a paradigm change of collaborative outlook
- a strong interaction with stakeholders including outreach for the public, and a platform of industrial partners
- improved use of interdisciplinary working tools including management, discipline bridging and IT

Economic impact of the new CDT is focused through our industrial engagement programme, as well as our innovation training. Our partner companies include Nokia, Unilever, Dyson, BP, Hitachi, IBM, Microsoft, Sharp, Toshiba, Sumitomo, Nanoco, Renishaw, Aixtron, Thales, De La Rue, TWI, and local nano-SMEs including Cambridge Display Technology, Plastic Logic, Eight19, Base4, Sphere Fluidics, Mesophotonics, Cavendish Kinetics, Owlstone, and CCMOS. Such partnerships are crucial for the UK to revive high value manufacturing as the key pillar to lead for future technologies. To develop this strategy we link to the Manufacturing Catapult centre (CPI) and the new Cambridge Centre for Manufacturing in Large-Area Electronics.

Training impact emerges through not just the vast array of Nano techniques and ideas that our cohorts and associated students are exposed to, but also the interdisciplinary experience that accrues to all the academics. In particular the younger researchers coming into the University are plugged into a thriving programme that connects their work to many other sciences, applications, and societal challenges. Interactions with external partners, including companies, are also strong and our intern programme will greatly strengthen training outcomes.

Academic impact is fostered by ensuring strong coherent plans for research in the early years, and also the strong focus of the whole CDT on nanoassembly of functional nanomaterials and nanodevices. Our themed areas provide a strong goal-based rationale for the research directions, and also ensure high impact research will emerge. Our track record is already strong (even though our first students have not yet finished), including 1 Nature Chem., 1 Nature Mat., 4 ACS Nano, 2 Adv.Mat., 2 Ang.Chem., 5 Appl.Phys.Letts., 1 Chem.Comm., 2 JACS, 2 Nano Lett., as well as others, plus 5 patents in process. Our cohorts have given 32 talks at international conferences, and many posters. As well as our new patents, the CDT students have already directly spun-off one company (CamIn) and several more are being discussed.

Societal impacts arise from both the progression of our cohorts into their careers as well as their interaction with the media, public, and sponsors. We have a strong careers programme and industrial + academic breadth ensure researchers are well aware of their options, and constantly discussing with their peers. Our efforts to bring societal challenges to students' awareness frames their view of what a successful career looks like. We directly encouraged a wide variety of engagement, including interaction with >5000 members of the public each year (mostly pre-university) through Nano exhibits during public events such as the Cambridge Science Festival. We also run several public policy workshops, and will further develop this aspect through the Cambridge Centre for Science Policy. Longer term societal impact comes directly from our engagement with partner companies creating jobs and know-how within the UK.

Publications

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