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20 May 2021

Perovskite ink sellers will be part of the future solar supply chain

The nascent perovskite photovoltaic sector has an extreme variety of startups and approaches. Some, like Oxford PV, are developing and manufacturing a complete product from start to finish, while others develop only their particular innovation and then look to license it.

For example, the UK’s Power Roll has developed a microgroove architecture, but doesn’t make its own perovskite ink – that’s left to the likes of Solaires Enterprises, one of the younger perovskite startups.

In contrast to solar-grade polysilicon, perovskites are cheap, both in terms of raw materials and equipment. That doesn’t make it trivial to supply, as there’s still plenty of research to be done on what exact formulae should be used. “Perovskite” in this context refers only to the structure of the chemical compound, not the specific elements involved, which can vary.

Research into which formulae to use isn’t about a generic “best option”. While there are generic problems to be solved, especially as regards smooth coating and degradation, different perovskite variants also have different absorption spectra. This means there will be a variety of formulae used according to different situations. For example, the formula used for a solar module attached to an indoor device doesn’t need to have a longer lifespan than whatever it’s powering, doesn’t need to resist degradation from heat, cold or humidity, and will want a different absorption spectrum compared to a module that has line of sight to the sun.

As such there is room for an ongoing business model developing these formulae, and that is what Solaires Enterprises is pursuing – promising to develop a formula specific to the needs of each customer. This is comparable to Saule Tech’s adaptation of its perovskite module designs to the devices of their customers.

Even once perovskites have entered the mainstream, perovskite-perovskite tandems will be a while into the future, and those will benefit from experiments to cover as much of the right parts of the light spectrum as possible between several formulae. Solaires is looking into perovskite-perovskite tandems, but for now can’t even give an expectation of when they might be ready, or whether these would be tandems at the cell level, which is more powerful, or at the module level, which is less technically challenging.

Founded in Canada fifteen months ago with two co-founders, some patent ideas, and $3 million from friends and family, Solaires has grown to 21 employees, almost all researchers, and is accumulating patents and funding – from government, pre-seeded capital, and innovation programs for now. It’s early days yet, but Solaires is in contact with long-standing Canadian solar manufacturer ATS Industrial Automation among others.

Another reason for Solaires to keep tweaking its formulae is the prevalence of a variety of manufacturing techniques – inkjet techniques require a certain viscosity, and besides that Solaires ink is suitable for spin-coating, blade-coating, and slot-die techniques. However the company doesn’t deal with vapor deposition.

Once the business model is online, Solaires will receive a three-layer structure – with a flexible film, the device to be powered, and the electron transfer layer already coated. Solaires’ job will be to apply the ink and the hole transfer layer, using either roll-to-roll or sheet-to-sheet printing, depending on the scale of the product. The only non-fluid deposition would be a very thin layer of gold, but silver could be applied instead in a liquid form. Vapor deposition is costlier than other techniques, though perovskite leader Oxford PV does use vacuum deposition.

Solaires is looking to very small-scale applications – for solar-powered devices, where there is no entrenched competition from silicon PV, and for bendable thin-film modules. Rooftop, façade and then utility applications are further away for perovskites, and Solaires will pursue them only when the time comes. Solaires’ first proof of concept was “PV blinds” – at the tilt a blind blocks outdoor light, it is of course also absorbing sunlight.

Solaires’ product has reached 22% cell efficiency – which is respectable – but it remains unsure of lifespan, with more tests needed. This is because of its emphasis on devices, where there is no need for the module to outlive what it’s powering – but in time they will work towards 15 years.