Researchers at the University of Sheffield in the UK have created a spray-on solar cell that uses perovskite as the light-absorbing layer. Although the cell's efficiency is only a modest 11 percent, it can be manufactured very cheaply, paving the way for significant reductions in the cost of large-scale solar panel production.

High-efficiency multi-junction solar cells are useful for specialized applications like space probes and satellites, but their complex structures and use of rare, expensive materials makes them impractical for widespread use. When it comes to large-scale energy production, price per watt, rather than efficiency, becomes the fundamental metric. In the context of solar, this means trading off some performance in favor of much cheaper materials and simpler, more streamlined manufacturing.

Solar cells based on perovskites (a family of crystals with a common, distinctive structure) look very promising in this regard, for two main reasons. Firstly, they can be manufactured on the cheap, using widely available materials prepared at low temperatures. And secondly, the technology around them is advancing at an astonishing pace. In a few short years, they have already reached efficiencies in excess of 19 percent, which is competitive with traditional cells based on crystalline silicon.

Now, Prof. David Lidzey and colleagues at the University of Sheffield have managed to create a spray-on solar cell that uses perovskite as the light-absorbing layer. The efficiency of the cell was measured at 11 percent, which is only a fraction of silicon-based cells, however, the combination of perovskite and spray-on technology could cut the price per watt figure considerably, making a compelling case for cheap solar power on a large scale.

Depositing perovskite using spray heads could significantly reduce manufacturing costs (Image: Jon Griffin/University of Sheffield)

The researchers had previously used the same spray-painting method to produce organic solar cells, but they say that replacing organic compounds with perovskite as the light-absorbing layer has led to significant efficiency gains. Spray-painting perovskite can streamline the manufacturing process, making it easier to scale production, and also wastes little material.

In the absence of actual production lines and economies of scale, it is nearly impossible to tell how the price per watt of a spray-on perovskite will compare to standard silicon cells, which are energy-intensive to produce. However, given the very rapid pace at which they've been progressing over the past few years, researchers have reason to be optimistic.

"I believe that new thin-film photovoltaic technologies are going to have an important role to play in driving the uptake of solar-energy, and that perovskite based cells are emerging as likely thin-film candidates," says Lidzey.

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