Solar panels that can be coated onto thin, flexible surfaces could one day be made the way newspapers are printed, at room temperature and without the toxic chemicals the process has relied on, claim researchers from the University of Surrey.
In a paper published in the journal Nano Energy, scientists set out a lower-toxicity way to make perovskite solar modules at the scale a factory would need. Perovskites are a leading candidate to sit alongside or replace conventional silicon solar cells, because they can be dissolved into an ink and coated onto lightweight, bendable surfaces. The problem for perovskites is that the ink itself depends on solvents that are hazardous to handle and costly to manage on a production line.
The Surrey research team produced their ink around safer ingredients. Their system, which they call a significantly reduced-toxicity (SRT) solvent, is based on ethanol and 2-methyltetrahydrofuran, a solvent derived from renewable sources such as farm and forestry waste, with a small amount of a milder additive to control how the film forms. It removes the need for the toxic solvents the field has long leaned on, including dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP) and acetonitrile (ACN), several of which are classed as reproductive toxins.
The researchers note that producing a gigawatt of electricity from these perovskite modules can consume more than 90,000 liters of solvent on a single coating line, so cutting toxic solvents out of the ink removes a real health and environmental burden from manufacturing.
To show the recipe works beyond a single cell, the team built mini-modules with active areas up to 11.5 square centimeters and reached power conversion efficiencies above 18 percent, among the highest reported for greener, scalable perovskite processing. The modules also stayed stable under continuous light during testing.
Dr Ehsan Rezaee, lead researcher of the study from the University of Surrey, said:
“We are designing the chemistry of perovskite materials together with the manufacturing process, with industry in mind. For a technology to move from the laboratory into a real manufacturing environment, we need to consider not only performance, but also the solvents, processing conditions, safety, resource use and overall complexity of production.”
The approach is built for continuous, high-throughput production. The ink is coated at room temperature and dried with a jet of gas, a step compatible with roll-to-roll manufacturing, the same principle used to print newspapers at speed. The team has shown it working on flexible surfaces, which is where perovskite’s advantage over rigid silicon is clearest, from building surfaces and portable electronics to the lightweight panels needed for space.
The method also avoids the “anti-solvent” step that many perovskite recipes need, a stage that usually introduces further toxic chemicals. By skipping it and working at low temperature, the process uses less energy and fewer materials.
Professor Ravi Silva, corresponding author and Director of the Advanced Technology Institute at the University of Surrey, said:
“The potential impact of our innovation extends beyond simply replacing a hazardous solvent. A process based on easy-to-use, non-toxic solvents and simpler coating steps reduces the need for solvent handling, waste treatment and the safety infrastructure that goes with them. That points to more compact, resource-efficient and potentially lower-cost manufacturing for emerging solar technologies. We want to help make clean energy available across the world, and if we can support decarbonization at scale in the same step, that is a double win for society.”
The paper was led by Surrey and involved researchers at the University of Oxford, the University of Cambridge, the Helmholtz-Zentrum Berlin in Germany, the MAX IV Laboratory in Sweden and the National Physical Laboratory. The research was supported by the Engineering and Physical Sciences Research Council and the EU Horizon 2020 project MUSICODE.