The SMARTLINE-PV project aims to develop scalable, environmentally friendly tin-based perovskite solar cells, addressing the challenges of lead toxicity and improving crystallisation processes.
Photovoltaic solar energy conversion is of high importance in Europe’s transition toward a clean, resilient, and climate-neutral energy system. While silicon solar modules dominate today’s PV market, their rigidity, weight, and limited design flexibility constrain their use in many emerging applications. In contrast, next-generation thin-film photovoltaic technologies, particularly perovskite solar cells, enable solar energy generation in areas where conventional photovoltaics are less suitable.
Among these emerging technologies, perovskite solar cells have attracted great attention over the past decade. Their rapid rise in power conversion efficiency, now exceeding 27%, combined with low-temperature processing and compatibility with flexible substrates, positions them as a disruptive alternative to conventional photovoltaics. However, these high-performance perovskite solar cells contain lead, which raises environmental and societal concerns and could challenge large-scale deployment.
The EU-funded Horizon Europe project SMARTLINE-PV addresses this challenge by developing scalable, tin halide perovskite solar cells with the focus on innovative crystallisation technologies. By combining material innovation, plasma-assisted processing, ecodesign, and application-driven demonstrators, SMARTLINE-PV aims to unlock new areas of applications, in particular, in the rapidly growing fields of Internet of Things (IoT) devices and Building-Integrated Photovoltaics (BIPV).
A strong European consortium driving innovation
SMARTLINE-PV brings together a multidisciplinary consortium of 13 partners from across Europe, combining academic and applied research expertise, and industrial know-how. The universities and research organisations (Graz University of Technology, HZB, Joanneum Research, CNR, Fraunhofer ISE, CEA, and bifa Umweltinstitut) lead the development of advanced tin perovskite materials, crystallisation chemistry, device architectures, module integration, sustainability assessment, and circularity, while the industrial partners (INO GmbH, temicon, Homerun Energy, COMTES FHT, Terran and FILBAU) focus on scalable processing, roll-to-roll compatibility, and market-oriented design. This tightly integrated collaboration enables SMARTLINE-PV to bridge the gap between fundamental materials research and industrially relevant photovoltaic solutions, enabling a transition from laboratory innovation to deployable clean-energy technologies.
From lead to tin: A sustainable materials shift
Replacing lead with tin in perovskite solar cells is a promising route towards environmentally friendly photovoltaics. Tin halide perovskites share many of the favourable optoelectronic properties of their lead-based counterparts, including strong light absorption and excellent charge transport. Encouragingly, tin-based perovskite solar cells have already demonstrated efficiencies exceeding 17%.
Despite this progress, several critical challenges remain. Tin perovskites are prone to fast crystallisation, high defect densities, and chemical instability, in particular, due to the oxidation of Sn2+ to Sn4+. These factors negatively impact device efficiency, reproducibility, long-term stability, and large-area fabrication.
SMARTLINE-PV tackles these issues through novel precursor chemistry and crystallisation control strategies. Innovative crystallisation mediators are designed to slow down the crystal formation process, allowing tin perovskite films to grow with fewer defects and improved structural uniformity. In parallel, the project explores non-oxidising solvents, hydrogen-bond interactions, and halide-halide interactions to stabilise the tin oxidation state and further improve film quality. These material innovations lay the foundation for high-performance, stable tin halide perovskite solar cells that are suitable not only for laboratory demonstrations, but also for industrially relevant manufacturing.
Plasma-assisted crystallisation for scalable manufacturing
Conventional perovskite fabrication often relies on anti-solvent dripping, a process that is difficult to control, solvent-intensive, and not well suited for large-area or roll-to-roll production. In contrast, the plasma-assisted approach, investigated in SMARTLINE-PV, enables fast, solvent-free crystallisation at low temperatures, offering good control over nucleation and crystal growth. By combining optimised precursor formulations with carefully tuned plasma conditions, uniform and high-quality perovskite films can be produced without anti-solvents. This process is also well compatible with roll-to-roll (R2R) manufacturing, enabling continuous deposition on large-area flexible substrates. This compatibility represents an important step toward industrial scalability, reduced energy consumption, and lower production costs.
Device engineering for efficiency and stability
In addition to the optimisation of the perovskite absorber, SMARTLINE-PV focuses on customising the device architecture specifically for tin perovskites. Tailored interlayers are developed to enhance charge extraction, suppress recombination losses, and protect sensitive interfaces within the solar cell stack. Novel device architectures are explored to improve mechanical flexibility and long-term operational stability under real-world conditions.
Through this integrated approach, SMARTLINE-PV aims to achieve efficiencies above 20% for tin-based perovskite solar cells, an ambitious but realistic target that would highlight the potential of this solar cell technology as a viable alternative to established thin-film technologies.
Coloured modules through the MorphoColor concept and building integration
In the built environment, solar energy systems are expected to combine performance with design and functionality. SMARTLINE-PV addresses this by enabling colour variation in tin perovskite solar cell modules through the MorphoColor concept, which is inspired by the structural colouration found in butterfly wings. The MorphoColor concept relies on photonic structures that combine geometrically patterned substrates with interference layers to create bright, customisable colours without relying on pigments. This approach enables perovskite solar modules with selectable colour, which are ideally suited for architectural integration.
For BIPV applications, this design freedom is transformative. Facades, sunshades, and roof elements can simultaneously generate electricity and contribute to the visual identity of buildings, an essential factor for deployment in urban and historic environments.
Ecodesign, circularity and low carbon footprint
Sustainability is a guiding principle throughout SMARTLINE-PV. The project integrates eco-design and circularity concepts across the entire lifecycle of the solar cells, from raw materials and manufacturing to use, recycling, and end-of-life considerations. Low-temperature, fast processing reduces energy demand during fabrication, contributing to a low carbon footprint compared to conventional photovoltaic technologies. The elimination of lead and solvent-intensive processing further enhances environmental compatibility and social acceptance.
Demonstrators supporting technology transfer
To bridge the gap between laboratory research and practical deployment, SMARTLINE-PV places strong emphasis on application-oriented demonstrators. Flexible tin perovskite solar modules are integrated into IoT devices, enabling autonomous, maintenance-free power supplies for sensors and smart systems.
In parallel, BIPV demonstrators showcase the integration of flexible, colour-selectable modules into building elements such as roof tiles and sunshades. These demonstrators are tested under real-world conditions, providing valuable data on performance, durability, and user acceptance.
Shaping the future of thin-film photovoltaics
By addressing efficiency, scalability, sustainability, and aesthetics through a holistic approach, SMARTLINE-PV represents a significant step toward a new generation of thin-film photovoltaics. The project demonstrates that tin-based perovskite solar cells can move beyond niche research topics and become viable candidates for real-world applications.
SMARTLINE-PV demonstrates how advanced materials research, innovative processing, and thoughtful design can be combined to develop practical and impactful photovoltaic solutions. By addressing both technical performance and integration aspects, the project supports the broader adoption of photovoltaics in everyday applications and contributes to a more sustainable built environment.
Disclaimer
This project has received funding from the European Union’s Horizon Europe research and innovation programme under grant agreement no. 101122327.
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