According to the Fraunhofer Institute for Electron Beam and Plasma Technology (FEP), this was achieved through a combination of materials research, roll-to-roll (R2R) pilot production and sustainability measures.
Efficiency and favorable production processes count
The researchers have already developed solar cells with an efficiency of over 21% on flexible PET substrates. The most important 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 perovskite stack coated entirely in a roll-to-roll process with slot die inks.
In parallel, VTT and TNO have scaled up 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 has also developed an encapsulation that keeps the solar cells stable for over 2,000 hours under wet-heat conditions (85 °C temperature and 85 % humidity) - proof of their durability in real applications.
"Our flexible perovskite cells have already surpassed 21% efficiency on bendable substrates, and we have demonstrated scalable roll-to-roll processes," says Dr. Riikka Suhonen from 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."
Consortium focuses on sustainability
The consortium attaches great importance to sustainability. Initial life cycle analyses show that the use of carbon electrodes, recycled PET and green energy can reduce thecarbon footprint by more than 50%. In addition, processes have been developed to recover materials such as lead and caesium from production waste.
In the second phase of the project, Pearl plans to 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.