Researchers in France have achieved 19.18% power conversion efficiency for flexible single-junction perovskite solar cells having an active surface area of 33 mm², announced the country's National Solar Energy Institute (INES), operating under the Alternative Energies and Atomic Energy Commission (CEA).
The team admitted that it is not the highest performance since higher efficiencies have been achieved for flexible perovskite in the past, but said its technology 'reconciles simplicity and performance' (see 22.6% Efficiency For Flexible Foldable Perovskite).
According to INES, it has already obtained record performances with regard to the device surface achieving 20.3% efficiency on 11.2 cm², using glass as a rigid substrate. They transferred this technology onto a flexible substrate, by adapting the thickness of the active layer to the optical specificities of the substrate as polyethylene terephalate (PET) and indium tin oxide (ITO), and the ratio of iodine to the bromine content to better tune the bandgap. The end result was 19.18% efficiency.
Researchers deployed a double-cation perovskite layer of cesium and formamidinium as a planar structure that they believe has promising results. "Accelerated aging damp heat tests (at 85°C/85%RH) conducted at CEA on similar encapsulated flexible cells retained 90% of their initial efficiency even after 800h testing," added INES.
The team said it is now working in parallel to realize larger flexible modules with a view to achieve even higher performances. At the same time, they are also working on industrially scalable deposition methods for different layers in the stack on high area substrates.
This achievement follows 18% efficiency the researchers at CEA-INES achieved for perovskite solar modules in February 2021 (see 18% Efficiency For Perovskite Solar Modules).
CEA-INES said it is working on advanced materials, from cell to encapsulant to develop flexible, fully printable perovskite solar cells with an efficiency of 22% and a minimum of 80% initial performance after relevant accelerated tests from standards, under Apolo Project, financially backed by the European Union's Horizon 2020 research and innovation program. Its ultimate aim is to reach module cost below €0.40 per W.