SolCore Silicon Tandem Workshop

Dr Phoebe Pearce and NED delivered a three day workshop on Silicon Tandem Solar Cell Computer Modelling at Sungkyunkwan University, South Korea, 1-3 August 2023. Delegates included staff and students from SKKU in addition to industrial participants. The delegates learned how to perform computer simulations using our open-source packages SolCore for PV device simulation and RayFlare for multiscale optical simulation. Further tutorials are planned, with the next being held at UNSW in October 2023.

The tutorial materials are available online at the solcore-education gitHub repository. Most of the examples can be run through a web-browser using Binder by following this link.

Bulk Photovoltaic Effect Efficiency Limit

The Bulk Photovoltaic effect is the means by which ferroelectric materials can generate electrical power from incident light. A resurgence of interest in ferroelectric materials has led to some speculation that the bulk ferrorelectric effect could improve solar power conversion efficiency. In a recent paper "Energy Conversion Efficiency of the Bulk Photovoltaic Effect" published in PRX Energy, Andreas Pusch and co-authors show that the power conversion efficiency of a bulk photovoltaic device is necessarily low owing to a very strict tradeoff between the photovoltage and electrical conductivity required to enable high power devices. We conclude that the efficiency of any practical bulk photovoltaic device will fall a long way short of the semiconductor Shockley-Queisser efficiency limit.

OMEGA-Silicon project starts

The OMEGA-Silicon project seeks to augment the efficiency of silicon solar cells using molecular singlet fission. The approach allows for quantum efficiencies in excess of 100% and provides a pathway to take conventional silicon solar cell technology to efficiencies above 30%. The project involves eight industrial partners, Canadian Solar, DASolar, JA Solar, Jinergy, Jinko Solar, Jolywood, Leadmicro & Xinhao Energy. The Australian Renewable Energy Agency is funding the project over a 5 year period.

Further details about the project can be found at the OMEGA-Silicon website.

Night-time solar power featured on A Positive Climate Podcast

NED spoke with Alex McIntosh and Nick Zeltzer on A Positive Climate podcast about the prospects for night-time solar power and the challenges that universities face in taking technology from the research lab to commercial scale.

Thermoradiative diode presentation at the IEEE PVSC

Ned delivered a presentation on "Demonstrating the Thermoradiative Diode: 'Generating Electrical Power Through Radiative Emission' at the 49th IEEE Photovoltaic Specalists conference in Philadelphia. If you missed the presentation you can catch it online below.

Questions are welcome, email Ned at : nekins@unsw.edu.au

Quick links to useful papers:

Experimental demonstration:

• Nielsen, M. P., Pusch, A., Sazzad, M. H., Pearce, P. M., Reece, P. J., & Ekins-Daukes, N. J. (2022). Thermoradiative Power Conversion from HgCdTe Photodiodes and Their Current–Voltage Characteristics. ACS Photonics, 9(5), 1535-1540.

Thermoradiative concept:

• Byrnes, S. J., Blanchard, R., & Capasso, F. (2014). Harvesting renewable energy from Earth’s mid-infrared emissions. Proceedings of the National Academy of Sciences, 111(11), 3927-3932.

• Strandberg, R. (2015). Theoretical efficiency limits for thermoradiative energy conversion. Journal of Applied Physics, 117(5), 055105.

• Buddhiraju, S., Santhanam, P., & Fan, S. (2018). Thermodynamic limits of energy harvesting from outgoing thermal radiation. Proceedings of the National Academy of Sciences, 115(16), E3609-E3615.

• Pusch, A., Gordon, J. M., Mellor, A., Krich, J. J., & Ekins-Daukes, N. J. (2019). Fundamental Efficiency Bounds for the Conversion of a Radiative Heat Engine’s Own Emission into Work. Physical Review Applied, 12(6), 064018.

• Ekins-Daukes, N. J., Sazzad, M. H., Al Kiyumi, L., Nielsen, M. P., Reece, P., Mellor, A., Green, M. A., & Pusch, A.  (2020). Generating Power at Night Using a Thermoradiative Diode, How is this possible.  In Proceedings of the 47th IEEE Photovoltaics Specialists Conference, (pp. 2214-2218).

Demonstrating a Thermoradiative diode

The thermoradiative diode is an optoelectronic device that generates electricity through the emission of radiant heat in the mid-infrared. The device can generate power from any warm surface, including the Sydney opera house roof radiating into the cold night sky - effectively solar power at night!

Today we can power a wristwatch, in the future thermoradiative power could deliver electrical power densities around one tenth of a PV solar panel.

The scientific research has been published in ACS Photonics and also received coverage in the popular press:

• "Night-time solar technology can now deliver power in the dark" UNSW Newsroom
• "Harnessing the Night Sky to Generate Electricity Can Complement Solar, Scientists Say" VICE
• "Australian researchers show solar power can be generated at night" ABC
• "Australian researchers crack ‘nighttime’ solar" PV Magazine
• "We Are A Step Closer To Nightime Solar Power" IFL Science

Singlet Fission Enhanced Photovoltaics is on the Horizon: How do we get there?

A new review lead article published in Chemical Physics Reviews lays out the progress made to date in silicon fission enhanced photovoltaics, an advanced PV concept that utilises multi-exciton generation in organic chromophores to reach a limiting efficiency of >40%, far in excess of the single junction limit. The study, lead by Dr Tayebjee at UNSW Sydney, also presents new pathways to practically realise this concept.

Novel alloys for high-efficiency photovoltaics

A detailed experimental and theoretical study of silicon-germanium-tin alloys, in collaboration with Christopher Broderick from Tyndall National Institute in Cork, Ireland, has been published in Physical Review Materials. An open access version of the paper can also be found on arXiv. The follow-up paper with further results is currently under review but can also be found on arXiv.

RayFlare: integrated optical modelling of solar cells

A stable version of the optical modelling package RayFlare has been published, alongside a paper in the Journal of Open Source Software. This package is an evolution of the optical modelling capabilities of Solcore, expanding them to include ray-tracing and method for combining different optical solvers in the same structure. Further details can be found in the documentation here.

Multi-junction solar cells paving the way for super high-efficiency

New perspective paper published in the Journal of Applied Physics presenting the state of the art in multi-junction solar cell technology and some thoughts on future directions.

Singlet fission and tandem solar cells reduce thermal degradation and enhance lifespan

Singlet fission is usually promoted as a means for increasing the efficiency of solar cells. There are however ancillary benefits since it can be an endothermic process and hence reduce the operating temperature of a solar panel. We quantify this thermal benefit in our new paper published in Progress in Photovoltaics.

Generating Power at Night using a Thermoradiative Diode, How is this Possible?

Ned presented how a thermoradiative diode can generate power from the night sky at the 47th IEEE Photovoltaics Specialists Conference in June 2020.

Paper on integrating Bragg reflectors into multi-junction solar cells.

Our SolCore PV simulation code was used to design a new type of multi-junction solar cell with an integrated Bragg reflector. Yajie Jiang shows how a spectrum-splitting collector where the solar cell is both a PV device and the dichroic mirror. Full text available from [ https://doi.org/10.1016/j.solmat.2019.01.011 ]

ACEx PV & Design Summer School

January in Sydney saw students converge on UNSW for the PV & Design summer school; a week-long initiative hosted with the Centre for Exciton Scienceto help science and engineering students develop innovative ideas for exploiting solar power. Professor Angele Reinders from the University of Twente in the Netherlands took the students through the process of design, supported by lectures on fundamentals of solar power by Ned and Dr Murad Tayebjee, and photochemistry and excitonic interactions by Professor Tim Schmidt. The students finished the week by pitching their preliminary designs and undertaking a practical session on Coogee beach, building luminescent solar concentrators with Alain Rives. The students will continue to develop their innovative designs over the coming months, some of which have already inspired new research activities. The outcomes of the workshop will be presented at the forthcoming IEEE Photovoltaic Specialists conference in June 2019 in Chicago.

Ned presents at the 23rd Australian Institute of Physics Congress

The AIP Congress in 2018 was held in Perth from 9-13th December. Ned gave a presentation to the Conference on Optoelectronic & Microelectronic Materials and Devices ( COMMAD 2018 ) on “III-V Solar Cells - present status and future prospects”

Phoebe and Ned present at the Fall MRS meeting, Boston

The group had two oral presentations in symposium ET11 on Emerging Materials and Device Concepts for Flexible, Low-Cost Photovoltaic Technologies

Phoebe presented her work on ‘SiGeSn as a Candidate Material System for use in Thin-Film Multi-Junction Solar Cells’, describing how this promising new semiconductor could lead to manufacturable and hence lower cost high efficiency multi-junction solar cells. The work is in collaboration with Andrew Johnson at IQE plc.

Ned’s spoke about ‘Demonstrating the Hot Carrier Solar Cell—The Ultimate Thin Photovoltaic Device’ describing how a thin 8nm layer of chromium metal can be used to almost completely extinguish sunlight and generate a photocurrent. The work is in collaboration with James Dimmock, former QPV group member, Matthias Kauer formerly at Sharp Laboratories Europe, Paul Stavrinou at the University of Oxford, Huiyun Liu and Jiang Wu at University College London. The work will shortly be published in a Special Issue of Semiconductor Science & Technology dedicated to hot carrier photovoltaics.

On the closing morning of the conference, Ned and Kyle Kyle Montgomery from US Air Force Research Labs chaired a rump session on “Wavelength Selective Photonic Structures Applications to Solar Cells”, reporting on results from our collaborative work on Interstitial light trapping, in addition to presentations from Seth Hubbard from Rochester Institute of Technology, Rao Tatavarti from Microlink Devices, Roger Welser from Magnolia Solar, Jeremy Munday from University of Maryland, Andrew Johnson from IQE and Stephen Bremner from UNSW Sydney.