Researchers at the University of Surrey have developed a lower-toxicity method for making perovskite solar modules at the scale a factory would need. Their method replaces the hazardous solvents the process has typically relied on with a system based on ethanol and a solvent derived from renewable sources. The work is published in the journal Nano Energy.
The researchers said the approach could allow solar panels to be coated onto thin, flexible surfaces at room temperature, in the way newspapers are printed. They said it could also remove the toxic chemicals that have been central to production until now.
Why solvents matter for perovskite solar modules
Perovskites are a leading candidate to sit alongside or replace conventional silicon solar cells. They can be dissolved into an ink and coated onto lightweight, bendable surfaces. However, these inks depend on solvents that are hazardous to handle and costly to manage on a production line.
The solvents commonly used include dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP) and acetonitrile (ACN). Several of these are classed as reproductive toxins. According to the researchers, producing a gigawatt of electricity from perovskite modules can consume more than 90,000 litres of solvent on a single coating line.
A reduced-toxicity solvent system
The Surrey team calls its system a significantly reduced-toxicity (SRT) solvent. It is based on ethanol and 2-methyltetrahydrofuran, a solvent derived from renewable sources such as farm and forestry waste. A small amount of a milder additive is used to control how the film forms.
The method also avoids the “anti-solvent” step that many perovskite recipes need. That stage usually introduces further toxic chemicals. The researchers said that skipping it and working at low temperature means the process uses less energy and fewer materials.
Mini-module efficiency and stability
To show that the recipe works beyond a single cell, the team built mini-modules with active areas of up to 11.5 square centimetres. These reached power conversion efficiencies above 18 per cent, which the researchers describe as among the highest reported for greener, scalable perovskite processing. The modules also remained 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.”
Designed for roll-to-roll production
The ink is coated at room temperature and dried with a jet of gas. The researchers say this step is compatible with continuous, high-throughput roll-to-roll manufacturing. The team has demonstrated the process on flexible surfaces, where perovskite’s advantage over rigid silicon is clearest. Potential applications range from building surfaces and portable electronics to the lightweight panels needed for space.
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 decarbonisation at scale in the same step, that is a double win for society.”
Research partners and funding
The paper is titled “Solvent systems with significantly reduced toxicity for high-efficiency perovskite solar modules: The route to scale”. It was led by Surrey and involved researchers at the University of Oxford, the University of Cambridge, 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.
Frequently asked questions
What solvent did the University of Surrey use to make perovskite solar modules?
The researchers used a significantly reduced-toxicity (SRT) solvent based on ethanol and 2-methyltetrahydrofuran, with a small amount of a milder additive to control film formation. 2-methyltetrahydrofuran is derived from renewable sources such as farm and forestry waste.
Which toxic solvents does the new perovskite process replace?
It removes the need for dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP) and acetonitrile (ACN). Several of these are classed as reproductive toxins.
How efficient are the lower-toxicity perovskite mini-modules?
Mini-modules with active areas of up to 11.5 square centimetres reached power conversion efficiencies above 18 per cent. They also remained stable under continuous light during testing.
Can the process be used for roll-to-roll manufacturing?
The researchers say it can. The ink is coated at room temperature and dried with a jet of gas, a step they describe as compatible with roll-to-roll manufacturing, and the team has demonstrated it on flexible surfaces.
Where was the perovskite solvent research published?
It was published in the journal Nano Energy under the title “Solvent systems with significantly reduced toxicity for high-efficiency perovskite solar modules: The route to scale”.
