Using a blade coating, Italian researchers have developed a flexible solar cell that does not contain toxic dimethyl sulfoxide. They used the cell to make small solar modules with an efficiency of up to 6.58%.
“All the layers are manufactured in ambient conditions with a relative humidity of about 30-40%, so the manufacturing process does not require cleanrooms and controlled environments,” researcher Farshad Zafarzadeh said. pv magazine. “Furthermore, the use of highly toxic solvents has been avoided, which is a step towards the sustainability of perovskite solar cells.”
In the paper “All-Blade-Coated Flexible Perovskite Solar Cells & Modules Processed in Air from Sustainable Dimethyl sulfoxide (DMSO)-Based Solvent System” published recently Sustainable energy and fuels, Zafarzadeh and his colleagues described the blade coating as high performance coating method that requires a simple equipment and can be transferred to roll-to-roll manufacturing with minor changes.
“Blade coating perovskite layer in the surrounding environment is only possible with hot casting, gas quenching, vacuum extraction or a combination of these methods to prevent the spread of moisture during the perovskite phase,” they said.
In the manufacturing process, the researchers used dimethyl sulfoxide (DMSO), a toxic solvent commonly used in perovskite deposition, only in the first step, while in the second step they used isopropyl alcohol (IPA). In this way, DMSO is not trapped in the perovskite layer after the deposition is completed.
They built a cell an indium tin oxide (ITO) substrate, a tin(IV) oxide (SnO2) buffer layer, a perovskite absorber and a hole transport layer (HTL) made of polytriarylamine (PTAA).
“The solar cells are coated with large coatings bases (5×7 cm2), but measured on a small scale of 0.09 cm2 active area and master the device achieved a power conversion efficiency of 14.08%,” they said.
The Italian group also produced small solar modules based on this cell technology and even achieved an efficiency of the 21st century 6.58%.
“We demonstrated that this method is scalable at 13 cm2 × 13 cm2 sizes for flexible platforms. We are now working to improve the performance of the modules and further scale the devices,” said Zafarzadeh. “Although a cost analysis is beyond the scope of this work, we know that blade coating is an inexpensive technique due to its simplicity and low material waste.”
He also claims that the manufacturing process can be moved to roll-to-roll production, which enables fast, inexpensive and large-scale production. “Not to mention, the use of flexible platforms significantly reduces the overall weight of the solar modules, reducing transportation and maintenance costs,” he said.
In March 2021, the University of Rome Tor Vergata presented a perovskite solar module with a total active area of 42.8 cm2 and an aperture area of 50 cm2. The panel was built with 20% efficient perovskite cells connected in 14 series. It was able to retain 90% of the original efficiency after 800 hours of thermal loading at 85C.
Three months later, it unveiled a perovskite solar module with cells the triple cation cesium methylammonium formamidinium (CsMAFA). And in April 2022, it introduced a perovskite solar panel with a total substrate size of 20 cm × 20 cm and a stabilized power conversion efficiency of 11.9%.