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Our aim is to understand, develop and exploit functional nanolayer materials for next-generation optoelectronic devices and integrated circuits.

About us

We are a dynamic, interdisciplinary research group working on a variety of electronic device materials.

Join us

Explore our complete list of publications and PhD theses, most of which we have made open access and open data via ora.ox.ac.uk.

Publications

Roadmap on established and emerging photovoltaics for sustainable energy conversion

J. Phys. Energy 6 (2024) 041501. Photovoltaics (PVs) are essential for cutting greenhouse gas emissions and meeting future electricity demand. To achieve net-zero emissions, global PV capacity must grow from 0.9 TW in 2021 to 8.5 TW by 2050. This paper reviews recent progress in improving PV efficiency, stability, and cost, while also exploring emerging technologies like indoor PVs, space PVs, and agrivoltaics. >80 UK-based scientists joined efforts to highlight key challenges and opportunities for future research and development across more than 10 different fronts of PV technology.

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Enhancing dielectric-silicon interfaces through surface electric fields during firing

Solar Energy Materials and Solar Cells, Volume 269, 112799, 2024. Hydrogen passivation from dielectrics plays a pivotal role in enhancing the performance of silicon solar cells. In our latest work, we demonstrate how controlling carrier populations through charge-assisted field effect passivation can influence interface chemistry. The chemical passivation of Si-SiO2-SiNx interfaces is determined by the electric field's polarity and strength. Achieving optimal processing requires managing surface electric fields, the chemical interface, hydrogenation, and charge migration.

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Characterization of solar cell passivating contacts using time-of-flight elastic recoil detection analysis

Appl. Phys. Lett. 123, 261106 (2023). Detecting hydrogen in solar cell structures is key to understanding their performance and degradation. This study uses time-of-flight elastic recoil detection (ToF-ERD) to accurately identify hydrogen and deuterium in a poly-Si/SiOx contact. By analysing how particles scatter when hit with chlorine ions, the method provides clear, artifact-free data on hydrogen distribution. The technique offers detailed depth profiles of elements like silicon, nitrogen, oxygen, and hydrogen, helping researchers understand hydrogen's role in cell efficiency and durability.

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Towards a Graphene Transparent Conducting Electrode for Perovskite/Silicon Tandem Solar Cells

Progress in Photovoltaics: Research and Applications,1–15, 2023. We report a novel graphene doping technique via thin film ‘ion-charged dielectrics’ compatible with perovskite/silicon tandem solar cells. By electrostatically doping graphene monolayers, we show a reduction of >60% in sheet resistance, with light transmittance through the graphene being entirely unaffected. Our model of perovskite/silicon tandem efficiency indicates that a doped graphene transparent conducting electrode could enhance cell performance while improving the sustainability of future solar energy devices.

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Design considerations for the bottom cell in perovskite/silicon tandems: a terawatt scalability perspective

Energy and Environmental Science, 10.1039/D3EE00952A, 2023. Perovskite/silicon tandem solar cells are poised to take over as the market-leading technology. However, the processing approaches and materials in high-efficiency tandem demonstrations are incompatible with mass production. We highlight the disconnect between current research-based techniques and the stringent constraints imposed by large-scale mass manufacturing, identifying the critical design criteria for this technology to become a commercial reality.

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Ion-Charged Dielectric Nanolayers for Enhanced Surface Passivation in High Efficiency Photovoltaic Devices

Advanced Materials Interfaces, 2300037, 2023. Here we use ion-charged oxide nanolayers to enhance the passivation of silicon surfaces via the field effect mechanism. We provide first report of enhanced passivation from rubidium and caesium ion-charged oxide nanolayers. The charge state and formation energy of ion-charged silicon dioxide are calculated from first principles. Optimal ionic charge concentration of ≈1.5e12 q cm−2 leads to a recombination velocity and current density as low as 2.8 cm s−1, forecast to provide efficiency improvements as high as 0.7% absolute.

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Recombination in Passivating Contacts: Investigation Into the Impact of the Contact Work Function on the Obtained Passivation

Solar RRL, 2201050, 2023. Improving contacts in silicon solar cells is crucial for reaching high-efficiency and low-cost solar electricity. Here we study the impact of the metal work function on the contact electrical characteristics. The surface saturation current density is extracted from photoluminescence and simulated to gain insights into the interface charge dynamics. Suitable metals should be deployed to minimise losses in high-efficiency solar cells.

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Sustainability evaluations on material consumption for terawatt-scale manufacturing of silicon-based tandem solar cells

Progress in Photovoltaics, Research and Applications, 2023,1–13. Here we show that III-V, CIGS and CdTe are unsuitable for TW-scale solar manufacturing. Si-Pvk tandems the most sustainable as long as indium is not required. Additionally, while tandem cells can reduce silver consumption / kW, the PERC cell architecture could allow for significantly reduced Ag consumption compared with both TOPCon and SHJ.

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SiNx and AlOx Nanolayers in Hole Selective Passivating Contacts for High Efficiency Silicon Solar Cells

IEEE Journal of Photovoltaics, vol. 13, no. 1, pp. 22-32, 2023. Maximising the efficiency of silicon solar panels requires the use of passivating contacts with nano-interlayers that limit the loss of charge at silicon/metal interfaces. Here we investigate silicon nitride and aluminium oxide as novel nanolayers that provide passivation while allowing charge flow. We show that these nanolayers have significantly lower resistivity than current standard silicon oxide. A promising reduction in loss was shown with the AlOx interlayer, in part due to the dielectric intrinsic high negative Q

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Our Research

Our research aims to understand the interfaces between electronic materials, develop new processing for advanced nanolayer materials, and apply them to new and improved electronic, optical, electrochemical, and computing devices.

Featured Publications

Roadmap on established and emerging photovoltaics for sustainable energy conversion

Enhancing dielectric-silicon interfaces through surface electric fields during firing

Characterization of solar cell passivating contacts using time-of-flight elastic recoil detection analysis

Towards a Graphene Transparent Conducting Electrode for Perovskite/Silicon Tandem Solar Cells

Design considerations for the bottom cell in perovskite/silicon tandems: a terawatt scalability perspective

Ion-Charged Dielectric Nanolayers for Enhanced Surface Passivation in High Efficiency Photovoltaic Devices

Recombination in Passivating Contacts: Investigation Into the Impact of the Contact Work Function on the Obtained Passivation

Sustainability evaluations on material consumption for terawatt-scale manufacturing of silicon-based tandem solar cells

SiNx and AlOx Nanolayers in Hole Selective Passivating Contacts for High Efficiency Silicon Solar Cells

Lab News

Sebastian's comment on the recent tandem solar cell world record

The Silicon PV comes to Oxford

Congratulations to James McQueen

Group attends the 14th Silicon PV Conference, Chambery, France

Group attends the 18th PVSAT conference, Glasgow, UK

Anastasia is awarded Marie Sklodowska-Curie Postdoctoral Fellwoship

Congratulations to Yan Wang

Group attends PVSEC-34, Shenzhen

Matt publishes in The Conversation

Group attends 17th Photovoltaics Science, Applications and Technology (PVSAT-17) Conference

Matt is awarded Marie Sklodowska-Curie Postdoctoral Fellwoship

Our work is featured in PV Magazine