Solar energy generation is forecast to play a critical role in the transition to low-carbon energy and achieving zero emissions targets within the EU and worldwide. For the EU, solar power is forecast to meet 20% of the EU electricity demand in 2040^[1], reaching 20TW by 2050 with the installation of 632GW p.a.^[2]. Power from solar and other light sources is also a convenient energy source to power autonomous devices in an increasingly connected world for example applications such as roadside signage or indoor self-powered sensors. Solar cells can also be integrated with building structures to reduce building energy requirements from other sources.

Silicon (Si)-wafer based PV technology accounted for about 95% of the total production in 2020[3]. Despite major advances over recent decades, there are a limitations to Si-based photovoltaics (PV) including cost to manufacture the panels which relates directly to the levellised cost of electricity from solar, the fact that global semiconductor Si supply is constrained and it is on the EU list of critical materials[4] and high energy consumption and associated greenhouse gas emissions associated with Si foundry processes.

Metal-halide perovskite solar cells (PSC) have seen rapid advances over the last decade with power conversion efficiency (PCE) now comparable to that of Si cells³. In contrast to Si, perovskites can be deposited using low-temperature solution-based processes and high-volume production methods such as printing onto a wide variety of substrates. Perovskite raw materials are not based on critical materials. Perovskite solar cells could therefore be cheaper than Si in volume production. Another major attraction of perovskites is the property of tuneability where the bandgap and spectral response can be adjusted in the design of the material to meet different application requirements such as outdoor / indoor and mixed lighting conditions, shaded and building integrated solar collection or in different device architectures such as tandem.

Perovskite cells are not yet available commercially and to fully realise the potential of the technology requires overcoming a number of challenges including poor stability of the materials and degradation in performance, the use of some expensive or scarce materials in charge transport and electrode layers such as spiro-OMeTAD and ITO, and concerns over lead (Pb) toxicity to humans and the environment.

To address these challenges, SUNREY will develop a range of new material and device concepts to boost performance and enhance stability, maintaining a focus on scaleable low-cost and sustainable production, and minimising environmental hazard. These are summarised in Figure 1.1.

Figure 1.1 SUNREY technology innovations for transforming perovskite PV performance, durability and sustainability. A new solution for making highly efficient 2-D perovskites will improve stability and efficiency. Novel electron transport layers and architectures tuned to the perovskite band structure improve stability and efficiency whilst opening up a wide range of possible applications. New approaches to encapsulation, supported by model-based approach to degradation mechanism analysis and optimisation of solution-based and hybrid processes are also applied to conventional perovskite as well as novel and Pb-free materials.

SUNREY innovations related to the call topic scope:

“Research and resolve the degradation issues/mechanisms encountered from material to module”

Sunrey will develop enhanced characterisation and modelling methods including use of electrical impedance spectroscopy coupled with modelling and material characterisation including interaction between environment, materials and structure to better understand degradation pathways and predict lifetime-limiting mechanisms. These models will be linked to accelerated testing regimes and test equipment design to provide the basis for material and device optimisation and for prediction of device and module lifetime. This activity will encompass the influences of module design, encapsulation and barrier properties as well as material design and cell architecture.

“Produce stable and highly efficient perovskite PV architectures/modules by optimizing the constituent materials, the architecture of the cell, the interfaces, the interconnections between cells, the environment conditions during the fabrication steps of cells and modules, the encapsulation of cells and modules, etc.”

SUNREY will:

• Introduce novel interface and charge collection layers to improve stability of perovskite photovoltaic materials and cells, particularly emerging Pb-free materials to mitigate stability problems in these materials and provide compatibility with low-cost solution-based processes. Charge transport layers will be tunable to enable rapid adaptation of the design to new applications such as indoor light harvesting.
• Develop hybrid vacuum / solution processing methods to optimise growth and deposition conditions and embed passivation / stabilising layers to enhance stability of perovskite materials and solar cell structures
• Develop novel approaches to encapsulation and barrier materials including the use of nano-filled polymer encapsulants and conformal low-cost atomic layer deposition of low-defect impermeable layers. These will be combined with advanced encapsulation methods to provide the best combination of performance, stability and low cost.
• Develop simulation and optimisation tools for maximising performance and stability within the device architecture and to support lifetime prediction.

“Propose new device concepts and new materials (improved lead-halide perovskites or Pb-free perovskite analogues) to deal with any toxicity issues.”

SUNREY will develop novel mixed 2D/3D tin perovskites with conjugated p-conjugated organic diammonium cations to enhance the stability of Pb-free tin perovskite solar cells under operation from several hundreds to several thousands hours. Current lifetimes of Sn-based perovskites are too short for commercial applications.

“Ensure compliance with the relevant protocols (ISOS) at laboratory scale. Develop adequate stability assessment methods/measurements; propose and perform device/module real –life (under actual outdoor operating conditions) characterisation for reliability and energy yield assessment.”

SUNREY will perform comprehensive testing and evaluation at laboratory scale including outdoor testing and compliance with the relevant protocols (ISOS), characterisation for reliability and energy yield assessment and generation of data to support performance and lifetime models. Testing will be conducted by an accredited solar PV test lab (AIT) as well as at partner facilities around Europe.

“Identify environmental “hotspots” and how to address them. Perform a life cycle analysis (including decommissioning and disposal) to bring evidence of the low environmental impact, better resource efficiency than current commercial PV technologies, and circularity potential.”

SUNREY will develop comparative, toxicological and environmental impact models, including life cycle assessment and life cycle cost analyses (including decommissioning and disposal) to bring evidence of the low environmental impact and demonstrate better resource efficiency and more efficient circularity than current commercial PV technologies. These will be applied to materials and processes developed in the project, feeding back to the design process to ensure safe and sustainable designs.

“Extend application range”

SUNREY will develop scaleable processes to implement the new materials, solar cell and module designs with a focus on low-temperature solution-based processes that can be applied to a range of substrates such as flexible. The development of tuneable charge transport layers meets an important requirement for fully exploiting bandgap tuneability of perovskites. This will open up new applications with targeted markets including utility-scale panels, IoT and MicroPower, Independent Power Sources, Building Applied Utility Power (BAPV) Building-Integrated Photovoltaics.

[1] https://ec.europa.eu/info/research-and-innovation/research-area/energy-research-and-innovation/solar-energy_en

[2] https://about.bnef.com/new-energy-outlook/

[3] Fraunhofer Institute for Solar Energy Systems, Photovoltaics Report, 2021.

[4] https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:52020DC0474&from=EN