Fraunhofer FEP: Milestone in flexible perovskite solar cells – EU-funded PEARL consortium demonstrates roll-to-roll production

The researchers have developed solar cells with an efficiency of over 21% on flexible PET substrates. Key achievements of the project partners include:

• The Spanish research institute ICIQ achieved cells with an efficiency of 21.6% through special surface treatments (molecular surface passivation using fullerenes and silane-based self-assembled monolayers).
• The University of Rome Tor Vergata achieved 17.03% using more environmentally friendly solvents for the perovskite materials and optimized doctor blade coating processes.
• The Technical Research Center Finland VTT demonstrated a laboratory-scale record cell with an efficiency of 14.8% using a novel gravure printing process with DMSO-based perovskite inks.
• The Dutch research institute TNO achieved an efficiency of 9.1% with a fully roll-to-roll slot-die coated perovskite stack.

In parallel, VTT and TNO scaled up the R2R coating and patterning to larger formats and developed flexible mini-modules with an area of 36 cm² and a power conversion efficiency of 4.5%.

The consortium also developed an encapsulation that protects the solar cells for 2.000 hours under wet-heat conditions (85°C temperature and 85% humidity) – proving their durability in real-world applications.

“Our flexible perovskite cells have already surpassed 21% efficiency on bendable substrates, and we have demonstrated scalable roll-to-roll processes,” said Dr. Riikka Suhonen of VTT, the coordinator of the PEARL project. “These achievements bring our 25% target within reach – and pave the way to low-cost, high-performance solar modules for applications ranging from building-integrated photovoltaic systems to the Internet of Things.”

Focus on sustainability

The consortium places great emphasis on sustainability. Initial life cycle analyses show that the use of carbon electrodes, recycled PET and green energy can reduce the carbon footprint by more than 50%. In addition, processes have been developed to recover valuable materials such as lead and caesium from production waste – an important step towards a circular economy.

Outlook

In the second phase of the project, PEARL will further optimize its roll-to-roll pilot manufacturing processes, test larger modules for outdoor use and publish the results of the life cycle analyses. The aim is to bring flexible solar cells to market for applications such as building-integrated photovoltaics and the Internet of Things. Project deliverables will include an optimized module design report, R2R encapsulation processes and pilot-scale production protocols that together will establish Europe’s leadership in flexible perovskite PV manufacturing.

Together with its partners from the network of EU-funded perovskite projects, PEARL will exhibit at joint booth F6 at the EU PVSEC in Bilbao from 22-24 September 2025. PEARL will also be represented at this conference as a panelist in the “Perovskite Innovation Roundtable: Driving EU Leadership in Perovskite Innovation” (Monday, September 25 at 17:00).

About PEARL – Flexible Perovskite Solar Cells with Carbon Electrodes

The PEARL project started on October 1, 2023 and will run for 36 months. The project has received funding from the European Union’s Horizon Europe research and innovation program under grant agreement number 101122283.

This work has also received funding from UK Research and Innovation (UKRI) under the UK Government’s Horizon Europe funding guarantee (grant agreement number 10097706) and has received funding from the Swiss State Secretariat for Education, Research and Innovation (SERI).

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Further links

👉 www.fep.fraunhofer.de  
👉 www.pearl-project.eu  

Photo: VTT Oy