Perovskite solar research shifts to stability as Noak raises €5 million

For module makers and investors, the question has shifted. Cell efficiency is no longer the only gate. Heat, humidity and scalable deposition decide whether perovskite tandems reach factories. The newest lab results come from different architectures at small scale. None of them yet proves field lifetimes or manufacturing yields.

Noak's seed round

Noak is a spin-off from imec and Hasselt University in Belgium. Its technology builds on more than a decade of research at Hasselt University, imec and EnergyVille. The company says the tandem stack rests on five years of outdoor operating data from more than 10 test sites in Asia, Europe and North America. The Helios Foundation, Nuhma and V2HFin backed the seed round.

The cash goes to EnergyVille in Genk. There Noak will use existing research infrastructure and prepare gigawatt-scale manufacturing partnerships. It lands in a weaker venture market. Solar VC funding reached $2 billion across 60 deals in the first nine months of 2026, according to Mercom data. That is down 31% from $2.9 billion in the same period of 2025.

Noak's pitch is durability, not a record.

Why stability is the bottleneck

At the Korea Institute of Energy Research (KIER), researchers built a nickel oxide catalyst. It pulls lithium ions out of the hole-transport layer once lithium salts have driven the needed reactions. The champion cell reached 25.24% power conversion efficiency and 25.1% stabilized output under one-sun illumination. It had an open-circuit voltage of 1.175 V and a fill factor of 83.21%. It kept more than 90% of its initial efficiency after 500 hours of continuous operation, and 95% under damp-heat testing at 85 C and 85% relative humidity. The process also raised hole-transport-layer conductivity by a factor of 2.5. It oxidized spiro-OMeTAD in under five seconds without the additive tBP.

Argonne National Laboratory went after crystallization instead. Its team added zinc bromide and methylammonium chloride to lower the melting point of the perovskite and slow crystal growth.

Additives and interfaces

A review from Zhengzhou University argues that zwitterions can combine defect passivation, crystallization modulation and interfacial energy-level tuning in one molecular unit. Betaine-type zwitterions are the most studied class. In tin perovskites, L-asparagine raised efficiency from 10.54% to 13.31%. Formamidine sulfinic acid reached 22.06% in a wide-bandgap device.

The salt-assisted Argonne work produced a 26.5% solar cell and an LED with 26.1% external quantum efficiency.

Tin cells remain far behind their lead-based rivals. A CsSnI3 device reached 10.76%, up from 8.98% for an unoptimized counterpart built with the same materials and environment. The first CsSnI3 cell, reported in 2012, managed about 0.9%.

What happens next

Noak's design moves electrical connections to the rear of the cell with a three-dimensional woven back-contact foil. The company says this cuts shading losses. It also splits tandem cells into smaller series- and parallel-connected sub-cells to reduce metal use.

The company frames the seed round as groundwork for large-scale production, not a product launch. It has given no ship date for a commercial module.