The search for the cheaper, greener, more flexible solar cell is on. Now researchers at the Institute of Photonic Sciences (ICFO) in Spain have developed a new thin-film solar cell using earth abundant, non-toxic materials. The new photovoltaic (PV) devices are already 6.3 percent efficient.
"This is the first efficient inorganic nanocrystal solid-state solar cell material that simultaneously meets demands for non-toxicity, abundance and low-temperature solution processing,” said ICFO Professor Gerasimos Konstantatos, who led the work. “These first results are very encouraging, yet this is still the beginning and we are currently working on our next milestone towards efficiencies greater than 12 percent.” The other researchers were Dr. Maria Bernechea, Dr. Nicky Miller, Guillem Xercavins, David So, and Dr. Alexandros Stavrinadis.
Many technologies are promising including perovskite crystals, but they use toxic materials like lead. Others are working to develop those technologies without harmful elements but this research research at ICFO has developed a solar power device from the ground up without such materials.
They created a solution-processed, semi-transparent, flexible solar cell. The devices can be produced in ambient conditions at low temperatures, which is important because it further reduces the cost of producing the devices and requires less specialized, expensive equipment. The new cells are comprised of AgBiS2 (silver bismuth sulfide) nanocrystals, which the institute said are panchromatic light absorbers engineered transport charge.
"They contain AgBiS2 nanocrystals, a novel material based on non-toxic elements. The chemical synthesis of the nanocrystals allows exquisite control of their properties through engineering at the nanoscale and enables their dissolution in colloidal solutions. The material is synthesized at very low temperatures (100ºC), an order of magnitude lower than the ones required for silicon based solar cells,” Bernechea explained.
In developing the devices the researchers dispersed the nanocrystals into organic solvents. They remained stable for months without losing performance. They then deposited the nanocrystals on thin films until a thickness of roughly 35 nanometers was achieved.
The 6.3 percent conversion efficiency is on par with conversion efficiencies of other early stage development thin-film PV, according to ICFO. “This highlights the potential of AgBiS2 as a solar-cell material that in the near future can compete with current thin film technologies that rely on vacuum-based, high-temperature manufacturing processes,” it said.Tweet