A group of researchers at Dartmouth College in New Hampshire have developed a new flexographic printing method that can help manufacture Perovskite solar cells quickly and reliably. This new technique brings inexpensive mass printing of solar cells closer to reality. Perovskites are materials that have the same crystal structure as the mineral calcium titanium oxide, which was the first-discovered perovskite crystal.
These materials have shown potential for high performance and low production costs when used to create solar cells. The researchers documented their findings in a study titled, “Eliminating the Perovskite Solar Cell Manufacturing Bottleneck via High-Speed Flexography,” published in Advanced Materials Technologies.
The authors of the paper are Julia Huddy, a third-year PhD student at Dartmouth, Youxiong Ye who was a postdoctoral researcher at the university and is now working as a metallurgist at an American steel corporation and William Scheideler, Assistant Professor of Engineering at the university.
Currently, all the commercially produced solar panels use solar cells made from silicon which must be processed to very high purity. This energy-intensive process uses large amounts of hazardous solvents and is also very expensive. In comparison, these perovskite cells are made of layers of minuscule crystals made of low-cost light-sensitive materials. The raw materials can be mixed into a liquid to form a kind of ink that can be printed onto many different kinds of materials.
“I imagine a combination of traditional applications of solar such as utility-scale and residential rooftop solar, which are very cost-sensitive, as well as non-traditional applications in electric vehicles and mobile devices. Perovskite cells have strategic advantages when it comes to lightweight and flexible form-factor devices, so I think those emerging applications could be the most promising,” professor William Scheideler wrote in an email to indianexpress.com
“Silicon commercial cells are at approximately 21 per cent PCE (power conversion efficiency) for standard PERC technology. The best single-junction lab-scale Perovskite modules are now in the range of about 20 per cent PCE, so the drop off relative to commercial systems is no longer as sharp. The gap that still needs to close is the efficient drop for going to very large scale (1m x 1m) modules,” he added when asked about the efficiency of Perovskite solar modules.
Even though these materials are a really promising solution to increase global solar energy capacity, it is difficult to scale due to slow production times and high manufacturing costs.
The new printing method developed by the engineers at the Dartmouth Engineer combines high-speed flexography, where ink is applied to various surfaces using flexible printing plates, and sol-gel inks composed of perovskite crystals. This accelerates the processing time of the material by 60 times, according to the study.
While the new study is promising, the efficiency drop with large scale modules isn’t the only challenge that future research in this field will have to overcome.
“The next milestones for our group are to scale up the transparent electrodes and design materials that will be more flexible and robust. This is a huge challenge for monolithic solar cells that become limited by parasitic effects from the transparent electrodes (traditionally, ITO: Indium Tin Oxide),” Scheideler said while speaking about the future milestones for the research group. “We have new ink designs for scaling up these materials and making them more flexible. This could be key for any mobile applications of perovskite that need to be mechanically reliable under operational stresses and ageing,”
Another milestone for the researchers to get past would be the vacuum deposition of metal electrodes, which continues to be a costly step in the fabrication process. Improving the nanoparticulate inks for this application will be an important step toward enabling terawatt scale perovskite solar energy, according to him.