Silicon solar cell manufacturing is dominated by cell architectures that rely on a high-temperature energy-intensive diffusion process to introduce dopants. Such doped layers lead to substantial Auger recombination losses. Charged oxide inversion layer (COIL) solar cells eliminate the need for high-temperature diffusion and highly doped surface layers by incorporating charge in a surface dielectric to form an inversion layer emitter beneath the semiconductor-dielectric interface. The success of the COIL design hinges on achieving a sufficiently high dielectric charge to produce highly conductive inversion-layer emitters. In this work, we develop a new "hot-corona discharge" technique to facilitate the charge drive-in via a process integrating corona charging and thermal annealing into a single step. We show the process is effective in creating an n-type inversion layer on p-type silicon wafers, yielding increases in carrier lifetime and reductions in emitter sheet resistance. The temperature (330-430 degrees C) and time (30-1020 s) dependence of this new hot-corona approach is studied, demonstrating careful control over charge density. By optimising the process against temperature and ion drive-in cycles, we achieve the highest positive charge concentration reported on a SiO2/Si interface of >4.0 x 10(13) q/cm(2). With the ability to incorporate such high charge density, a low sheet resistance and highly conductive inversion layer can be formed. This represents a significant step forward in the attempt to replace the diffused emitter technology with a low-temperature alternative, enabling high-efficiency inversion-layer solar cells with reduced thermal budget and intrinsic losses.

Photovoltaic manufacturers now offer modules tailored for residential, commercial, and utility-scale applications, each with distinct design considerations related to power and weight. The average power-to-weight ratio—known as specific power—has improved significantly over the past two decades, with modern crystalline silicon modules delivering up to 2.7 times the specific power of earlier designs. However, the trend toward larger, heavier modules has introduced challenges in handling, transport, and reliability. This work provides a data-driven analysis of specific power trends in crystalline silicon modules over the past two decades, based on scientific literature and module datasheets. We quantify the influence of emerging cell technologies on module design and performance and provide a component-level breakdown of module weight. Recent advances in high-efficiency, lightweight crystalline silicon modules present new opportunities in specialized markets. Addressing the reliability challenges of large and lightweight modules is critical to enabling the next era of crystalline silicon photovoltaics.

The understanding of hydrogen and chemical interfaces in passivating contact stacks is critical for advancing high-efficiency silicon solar cells. This work employs time-of-flight elastic recoil detection analysis (ToF-ERDA) to profile elemental depth distributions, particularly the unambiguous characterisation of hydrogen, in key surface passivation dielectric nanolayers-SiNx, AlOx, and Al-doped ZnO (AZO). By leveraging the high mass resolution and low fluence of ToF-ERDA, combined with Monte Carlo simulations (MCERD), our work resolves hydrogen distributions and distinguishes overlapping signals from Si and Al, enabling precise analysis of interface composition. SiNx layers exhibit hydrogen contents up to 21 at.%, with redistribution and performance degradation observed after high-temperature annealing. In contrast, AlOx shows lower hydrogen content (similar to 2 at.%) but significant lifetime improvements post-annealing, indicating dominant field-effect passivation. For SiNx/AlOx double-layer stacks, enhanced hydrogen diffusion into AlOx was observed, suggesting SiNx as a hydrogen source. AZO/AlOx stacks demonstrated excellent passivation (iV(OC) > 730 mV) post-anneal, with hydrogen predominantly located in the AZO, challenging conventional views of AlOx as the main hydrogen source. These findings underline the value of ToF-ERDA for evaluating passivation mechanisms and demonstrate the tools versatility and usefulness in characterising dielectric nanolayers.

Transparent conducting electrodes (TCEs) combine high optical transmittance and electrical conductivity, and are an essential component of tandem solar cells. Although tandem cells offer a pathway to power conversion efficiencies exceeding 40% at low cost, they introduce new challenges for TCE design. Achieving the required balance of optical, electrical and chemical properties has so far limited practical TCEs in tandems to a small set of high-cost, indium-based oxides. Recent advances in computational and experimental techniques have improved understanding of TCE solid-state physics, revealing promising alternative materials. In this Review, we examine the material properties essential for TCEs in perovskite–silicon tandems, evaluate current candidates, and highlight the key challenges and opportunities for next-generation TCE development. Our goal is to bridge the gap between materials science and device engineering, providing a roadmap to accelerate the integration of advanced TCEs in high-efficiency optoelectronic devices. Transparent conducting electrodes are a key performance and sustainability bottleneck in high-efficiency perovskite–silicon tandem solar cells. This Review examines how optical, electrical and interfacial losses in transparent conducting electrodes arise in tandem cells and outlines strategies to enable scalable, low-indium electrodes for next-generation devices.

Overreliance on silver in solar cell manufacturing places an immense challenge on sustainability. Terawatt-scale solar energy generation is required within the next few decades, and current attempts to replace silver screen printing are inferior compared to conventional techniques. This work reports on a novel metallization methodology using a UV picosecond laser to ablate textured surface dielectric layers in a pattern defined by an in situ stencil shadow mask. Since the stencil mask does not need to be removed, a metal contact can be directly deposited employing printing or vapor deposition in one integrated process. Here, we demonstrate 26 μm wide metal fingers via thermally evaporated aluminum directly deposited onto laser-patterned point contacts of 16.9 × 19.1 μm2 size. Optical and electron microscopy analysis shows that the UV picosecond laser ablation damage is limited, and sufficient alignment is achieved. A line resistivity of 15.74 ± 2.35 Ω/cm and a contact resistivity of <10 mΩ·cm2 show the current-carrying capabilities of the contacts. Complete solar cell devices were produced using our new stencil self-aligned contacts, and electrical measurements show a pseudo-efficiency of 18.8%. This novel approach could potentially lead to a replacement of non-sustainable silver as front and back contacts for bifacial solar cells.

Tunnelling oxide passivating contact (TOPCon) silicon solar cells have risen to the mainstream in photovoltaic energy deployment worldwide. Enhancing the reliability and longevity of TOPCon solar modules will ensure the continuous growth of solar power on a multi-terawatt scale. This work investigates the mechanisms involved in surface-related degradation (SRD) in TOPCon passivating schemes, specifically focusing on two aspects. Firstly, TOPCon contacts can exhibit firing-induced instabilities that correlate with increased recombination from degradation in surface passivation. Secondly, we explored the influence of surface polarisation, induced by corona charging, on SRD by subjecting samples to various light soaking and annealing conditions. The results demonstrate that the presence of an electric field at the surface accelerates SRD, particularly under positive corona charge conditions. Effective lifetimes on symmetrical TOPCon specimens were significantly reduced and correlated to surface passivation degradation under positive polarisation. The degradation observed supports previous findings where charged hydrogen ions, which respond readily to electric fields, play a critical role in the observed degradation. This study contributes to the body of evidence aimed at understanding hydrogen kinetics at the SiOx/c-Si interface, providing valuable insights into the mechanisms driving SRD in TOPCon solar cells, with implications for enhancing the stability and performance of silicon solar panels.

High-efficiency solar cell architectures, including silicon heterojunction (SHJ) and perovskite/silicon tandems, rely heavily on the unique properties of transparent conducting oxides (TCOs). The push towards terawatt-scale PV manufacturing means it is increasingly desirable to develop indium-free TCOs to facilitate the upscaled manufacturing of high-efficiency cell designs. Aluminium-doped ZnO (AZO) deposited by atomic layer deposition (ALD) has emerged as a promising candidate due to its combination of optical transparency and electrical conductivity. In addition, AZO has also been shown to passivate the c-Si surface. The ability for one material to provide all three properties without requiring any indium is advantageous in single junction and tandem solar devices. Herein, we demonstrate exceptional silicon surface passivation using AZO/AlO x stacks deposited with ALD, with a J 0 < 1 fA cm-2 and corresponding implied open circuit voltage (iVOC) of 740 mV. We provide a comprehensive analysis of the role of ALD precursor dosing to achieve optimised performance. A broad range of characterisation approaches were used to probe the structural, compositional, and chemical properties of AZO films. These indicated that the passivation properties are governed by a delicate interplay between the Zn and Al concentrations in the film, highlighting the importance of precise process control. Optical modelling in a single junction SHJ architecture indicates these AZO films are close in performance to high-mobility indium-containing TCOs. The insights provided by this work may help to further the case of indium-free TCOs, which is critical for upscaled production of high-efficiency solar cells.

As part of the World Energy and Meteorology Council's (WEMC) seventh International Conference on Energy and Meteorology (ICEM), Royal Meteorological Society (RMetS) Energy Science Engagement Fellow Matthew Wright was involved in organising a workshop on Energy and Meteorology Education. Matthew co-organised this with Juan A. Añel, from the Universidade de Vigo and Spanish Royal Physics Society. The workshop was a success, with participants from across energy, weather and climate contributing to identify gaps and solutions in this important area. The workshop then split into breakout groups, to brainstorm gaps in energy and meteorology education and collaborate on a vision for this space. With attendees spanning academia, private companies and operational forecasters, each participant was able to bring their own expertise and experience to the discussion. We had a diverse range of experience and career stages present, from Master's and PhD students, to start-up founders and senior academics. This made for a varied and lively workshop experience. One of the biggest gaps identified by the breakout groups was the lack of connection between siloed departments in universities, or teams in companies. Whilst there is lots of expertise individually in energy, weather/climate and data science/machine learning, there is still not enough at the intersection of all three. All three are required to effectively meet the challenges facing the energy sector. Education in energy-meteorology should look to bridge the gaps between these three components. The difference between weather and climate education in the energy sector was another common theme. Attendees felt that climate change is incorporated and considered a lot more readily by energy companies than weather impacts are. More needs to be done to fill the hole between weather and climate, including improving the energy sector's understanding of sub-seasonal and seasonal forecasts. Simultaneously, it was agreed that there should be a focus on seamless weather/climate prediction services that enable the same skills to be used to analyse forecasts and projections across a range of timescales. Towards the end of the workshop, we touched on how to communicate the links between weather/climate and the energy sector to the general public (Figure 1). Juan and Matthew shared their personal experiences in this space, including Juan's media experience and RMetS's Climate Change Communications Training. Attendees agreed that the lack of understanding amongst the general public about weather/energy links needs addressing. For example, the group felt the public does not have a very deep understanding about the relationship between weather conditions and how much renewable power can be produced, and what this means for energy supply and price. Increasing the general public's understanding should be done with simple, clear communication that highlights the synergies between the energy consumers use, and the weather and climate. In terms of how the workshop sees future education in this space, the group felt it was important to maintain a balance of formal education courses and informal, on-demand courses like MOOCs. The latter could be taken by employees looking to ‘up-skill’, or brush up on a certain area that they do not have a formal background in. At the moment, both formal and informal courses are lacking in depth, breadth and availability. It is this lack of quality and availability that is the major barrier to energy-meteorology education, not the cost or the will to engage. Workshop attendees felt it was important that formal education courses, for example, Master's courses, are delivered in-person, or in a hybrid format. Informal education, such as short courses and self-learning, should be more flexible, with fully online and on-demand options. Currently, energy-meteorology education does not begin in school, but at universities (and often not until postgraduate level). Lots of value could be added by starting education about the links between energy, weather and climate earlier in the education system, for example, during physics lessons at school. Producing resources that can be used by teachers would help achieve this aim. This would sit alongside national curricula, and be complementary to the multitude of existing efforts to improve climate change and weather education. Overall, this was a successful workshop, but there is still much more work to be done to improve energy and meteorology education. RMetS will continue to work on improving educational resources for weather and climate, alongside organisations like WEMC. This will include producing resources (events, blogs and briefings) for the energy sector, as well as support for teachers earlier on in the education system through our ongoing educational programme. We are aiming to bridge the gap between weather and climate science and the energy sector to improve results in this important area. If you are interested in finding out more about the work RMetS does for the energy sector, sign up to our mailing list (at www.rmets.org/energy-special-interest-group). Matthew Wright: Writing – original draft; conceptualisation; resources; project administration; methodology. Juan A. Añel: Writing – review and editing; conceptualisation; resources; project administration; methodology. Hannah Mallinson: Conceptualisation; writing – review and editing.

An accurate description of the distribution of hydrogen at solar cell interfaces is critical for understanding both passivation and degradation phenomena. Time-of-flight elastic recoil detection analysis (ToF-ERDA) has recently been employed to study this hydrogen distribution by providing a one-dimensional (1D) depth profile. In this work, ToF-ERDA was used to investigate the hydrogen profile in a SiOX / SiNX passivating stack. The ability to resolve the interface with the c-Si interface was studied by using polished wafers and thin (20 nm) passivating stacks. This approach, coupled with Monte Carlo ERD (MCERD) modelling, showed that the identification of the interfacial oxide was much more clearly defined compared with previous reports using ToF-ERDA. Annealing the SiOX / SiNX at 450 °C for 5 minutes substantially increased the effective lifetime. However, no noticeable change in the H distribution measured with ToF-ERD was observed. We comment on the difficulty of correlating physical hydrogen measurements with the surface recombination properties.

Silicon heterojunction (SHJ) cell architectures, which have dominated silicon single‐junction efficiency records for the past 10 years, are processed at relatively low temperatures, on the order of ≈250 °C. Recombination‐active oxygen complexes in crystalline silicon, formed from interstitial oxygen (Oi), typically require temperatures higher than this to form. Therefore, it is typically assumed that SHJ cells are immune to such defects. This contrasts with the high‐temperature passivated emitter and rear cell (PERC) and tunneling oxide passivating contact (TOPCon) architectures, which can suffer from oxygen precipitates that are recombination active and difficult to predict. Herein, ring‐like defects are observed in boron‐doped p‐type SHJ solar cells, which leads to a degradation of open‐circuit voltage. It is shown that the spatial variation of this recombination activity is related to the boron–oxygen defect, the variation of which is likely due to the radial Oi distribution. Although boron‐doped p‐type wafers are no longer the industry standard, the defect engineering of wafers for SHJ production, using high‐temperature processing, is gaining significant interest. Such wafers can have an increased susceptibility to ring‐like defects. Therefore, spatially inhomogeneous defects causing recombination may become increasingly relevant for SHJ cells.

A highly efficient hole-selective passivating contact remains the crucial step required to increase the efficiency of polysilicon-based Si solar cells. The future development of solar modules depends on a device structure that can complement the electron-selective tunnel oxide passivating contact with an equivalent hole-selective contact. We investigate plasma enhanced chemical vapor deposited (PECVD) SiN x and atomic layer deposited AlO x as alternative nanolayers for the passivation layer in polysilicon tunnel contacts. We have fabricated p+ poly-Si contacts with resistivities below 100 m Omegacm2 using these alternative metal oxide and nitride nanolayers. Initial passivation tests yielded low levels of passivation; however, a detailed understanding of the nanolayers elucidated the strategies to improve passivation significantly, achieving an implied open-circuit voltage (iV OC) of 698 mV and dark saturation current density (J 0) of 34 fA/cm2 for a p+ poly-Si contact using a PECVD SiN x interlayer. These are among the best reported for nitride-based nanolayer tunneling contacts, with research into nitride-based tunneling contacts being still in its infancy.

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Indium-based transparent conducting electrodes (TCEs) are a major limiting factor in perovskite/silicon tandem cell scalability, while also limiting maximum cell efficiencies. In this work, we propose a novel TCE based on electrostatically doped graphene monolayers to circumvent these challenges. The electrode is enabled by a thin film dielectric that is charged and interfaced to a graphene film, optimally exploiting electrostatic doping. The field effect mechanism allows the modulation of charge carriers in monolayer graphene as a function of charge concentration in the dielectric thin film. Electrostatic charge was deposited on SiO2 membranes, and graphene transferred onto them exhibited a reduction in sheet resistance because of the induced charge carriers. We show a reduction in sheet resistance of graphene by 60% in just 3 min of dielectric charging, without impacting the transmission of light through the film stack. Hall effect measurements indicated that the mobility of the films was not significantly degraded. The deposition of negative electrostatic charge reversed this effect, allowing for precise tunability of charge concentration from n- to p-type. We develop a model to determine the required sheet resistance of a graphene TCE with 97% transmittance in a perovskite/silicon tandem cell. As the technique here reported does not impact transmittance, a graphene TCE with a sheet resistance below 50 Omega/square could enable efficiencies up to 44%, presenting a promising alternative to indium-based TCEs.

The International Technology Roadmap for Photovoltaics (ITRPV) is a globally recognized annual report discussing and projecting photovoltaic (PV) industry trends. Over the past decade, the silicon PV manufacturing landscape has undergone several rapid changes. By analyzing ITRPV reports from 2012 to 2023, we highlight some key discrepancies between projected industry trends and estimated actual market share. Some technologies have vastly exceeded the expected trends, e.g., the passivated emitter and rear cell and the use of gallium as the dominant p-type dopant. However, other projections have not occurred as quickly as expected, e.g., adopting silicon heterojunction cells and shifting to n-type wafers. In this work, we provide insights into the fidelity of projected trends by discussing some of the factors causing such rapid technological changes. By reflecting on 10 years of roadmap data, we highlight the fast-moving nature of the PV industry, meaning that business-as-usual projections must be assessed with caution.

High‐efficiency silicon‐based tandem solar cells will likely drive the push towards terawatt (TW) scale PV manufacturing on the pathway to net zero emissions by 2050. In this work, we provide a comprehensive analysis of material consumption and sustainability issues for future tandem solar cells. First, we analyse the material consumption and sustainable manufacturing capacity of a variety of potential candidates for the top cell in a silicon‐based tandem cell. We show that III‐V, CIGS and CdTe are not suitable to support TW‐scale manufacturing. Perovskites thus present the most sustainable approach, as long as indium is not required in the cell structure. Next, we turn our attention to the silicon bottom cell architecture by comparing PERC, TOPCon and SHJ. Although tandem cells can generally reduce silver consumption relative to single junction silicon cells due to the more favourable J MP / V MP ratio, the PERC cell architecture could allow for significantly reduced Ag consumption compared with both TOPCon and SHJ by relying on Al for the rear p‐type contact. In order to drive a rapid shift towards TW‐scale manufacturing, a rapid upscaling compared with the current production capacity is needed. The results presented herein highlight the need for careful consideration of sustainability issues when designing future high‐efficiency tandem cells that will help the world mitigate the dangers of climate change.

This review details the design considerations for the bottom silicon cell in perovskite/silicon tandems. The review highlights the shift in mindset required when transitioning to the mass production of tandem solar cells.

The RMetS hosted its second Climate Change Forum at the Coin Street Conference Centre, London, on 20 October 2022, with support from the Institute of Food Science and Technology (IFST),1 the Chartered Institute of Highways and Transportation (CIHT)2 and the Royal Institute of Chartered Surveyors (RICS).3 The event brought together academics, policymakers and professionals to discuss the actions needed within the next 5–10 years to reach Net Zero emissions by 2050. The Net Zero target was identified as necessary to achieve the Paris Agreement's 1.5°C goal as set out in the latest report by the Intergovernmental Panel on Climate Change (IPCC). The morning included keynotes from experts, with interactive discussions in the afternoon. Discussion groups focused on three sectors considered vital to reaching Net Zero: food, transport and buildings. The conference was opened by RMetS President Lesley Gray (University of Oxford). Jim Skea (Imperial College London) introduced the key messages and conclusions from the IPCC Sixth Assessment Report. The Forum heard that ‘human impact on the climate is indisputable’ and how we have already changed the climate in ways that affect billions of lives. Jim is a member of IPCC Working Group III (WG3; IPCC, 2022), which focuses on mitigation responses and offers some hope for the future. WG3's report suggests strategies to halve emissions by 2030, including for the green energy transition, land use changes, and to reduce demand for energy and products through lifestyle changes. Jim concluded that we do have the policy, economic and regulatory tools to reach Net Zero by 2050, they just need to be intensified and spread more widely. ‘The time for action is now’ (Figure 1). Swenja Surminski (Marsh McLennan, London School of Economics) spoke about climate risks and the importance of climate change adaptation (altering our behaviour and systems to protect society from the impacts of climate change), in addition to mitigation (preventing the planet warming further, by reducing greenhouse gas emissions). She gave insights from the third UK Climate Change Risk Assessment (UK Adaptation Committee, 2022), showing that climate risks have increased significantly over the last decade. These risks intersect with social inequality and could jeopardise some of the infrastructure required to reach Net Zero. Swenja finished by reminding us that society is too reactive: currently, only 12% of disaster management funds are spent on risk reduction (Tanner et al., 2014). The emphasis needs to shift to resilience and adaptation, to equip us for the effects of climate change. Second, Joanna Warner (Department for Business, Energy and Industrial Strategy [BEIS]) summarised the UK Government's Net Zero Strategy (BEIS, 2021) and associated activities. The Strategy was launched on 19 October 2021, just before the 26th Conference of Parties to the UN Framework Convention on Climate Change (COP26), and sets out policies and proposals for decarbonising all sectors of the UK economy by 2050. It aims to be ‘pro-business and pro-growth’, encouraging co-benefits, whilst helping the UK meet its international commitments. Whilst there has been disruption to energy markets over the past year, which have forced the Strategy to be adapted, the Government is still very much committed to Net Zero. Pete Falloon (Met Office) discussed what climate change means for the UK agri-food system. A key theme was the need to consider the food chain as a whole, ‘from farm to fork’, as opposed to just production. Pete summarised how to mitigate the food system's effect on the climate and adapt to the food security challenges climate change poses. Society's over-reliance on cars was highlighted by Jillian Anable (University of Leeds): current levels of car use would cause the transport sector to exceed its 2050 carbon budget by 2030 (Anderson, 2019). To avoid this, we need to reduce total car mileage, a shift to zero-emissions vehicles and increase public transportation usage. Alice Moncaster (Open University) stated that approximately 50% of global energy-related carbon emissions can be attributed to the building sector (UNEP, 2020), whether through operational use (e.g. heating, lighting) or through embodied carbon (e.g. construction materials and their transportation). To reduce this footprint, we must stop demolishing and rebuilding and start retrofitting, whilst using less carbon-intensive building materials, such as concrete and steel. After three exceptional talks, Liz Bentley (RMetS) chaired a panel discussion with the three speakers to hear the thoughts of the audience. Delegates were then able to view science posters over lunch. These highlighted the high standard of weather and climate data needed for understanding infrastructure risks from climate change, and some key methods for adaptation to climate change across the UK. Delegates divided themselves into three breakout groups, each focusing on a sector discussed in the previous session. Each group, with the help of industry experts, produced recommendations for climate change mitigation and adaptation within their sector. These recommendations were fed back to the group in a discussion facilitated by Becky Venton (RMetS) and chaired by David Warrilow (RMetS). Stephen French (IFST) chaired a lively discussion with the help of experts Christian Reynolds (University of London), Louise Manning (University of Lincoln) and Barnaby Coupe (The Wildlife Trust). Siobhan Campbell (Department for Transport) chaired this discussion and was aided by industry experts Saikat Barman (WSP), Rowland Potter (Executive Consultancy Services), Matt Tompsett (Kier Highways) and James Woodcock (University of Cambridge). Reflecting on Jillian's sectoral vision, much of the discussion focused on disincentivising car use and/or incentivising public transport use. The group agreed it is important to develop principles to guide climate action in the transport sector and appreciate the necessary trade-offs – now or in the future – for transportation to reach Net Zero. Industry delegates remarked that, even in highly emitting companies, the private sector (and individuals) will adapt if there is a clear roadmap to decarbonisation. The discussion was led by Rachel Capon (Mineral Products Association) with support from buildings experts Victoria Tink (Home Builders Federation), Ronita Bardhan (University of Cambridge) and Fabrizio Varriale (RICS). The discussion centred on the mitigation options highlighted by Alice, focusing on how retrofitting could be financially incentivised. Current barriers included a lack of incentives for renters or landlords, current energy performance certificates (EPCs) not reflecting a building's full life cycle and a labour/skill shortage. The final plenary session concluded that a whole systems approach is required, to implement complementary policy mechanisms across all three sectors. Current town planning systems must change to make Net Zero work from a food, buildings and transport perspective. Reliable data, tools and education are needed to increase people's awareness of their climate impact and help the public make climate-smart decisions. These shifts in public perceptions – for example, from viewing car ownership as a necessity, to seeing the benefits of public transport and carpool schemes – require collaboration across all sectors. Some of these transitions will take time, so policy emphasis should be put on those with proven technology and public backing. The meeting ended by highlighting the key role of the society in informing these much-needed future adaption and mitigation policies. The authors thank RMetS, IFST, CIHT, RICS and delegates.