Tiny gold mirror could make solar panels lighter, cheaper, and stronger

Researchers at the International Iberian Nanotechnology Laboratory (INL), in collaboration with Uppsala University, have developed an innovative ultrathin solar cell featuring a nanostructured gold mirror that significantly enhances light trapping and efficiency. By applying a very thin, patterned gold layer coated with aluminum oxide on the back of the cell, the design reflects light back into the cell for a second absorption, boosting efficiency by about 1.5%. The aluminum oxide layer also serves to reduce electrical losses through interface passivation, preventing energy-wasting electron recombination. This approach addresses two major challenges in ultrathin solar cells: improving photon capture and minimizing energy loss, thereby making these cells more practical for real-world applications. The team employed a cost-effective and scalable one-step nanoimprint lithography technique to create the nanostructured mirror, enabling industrial-scale production. Tested on ultrathin ACIGS thin-film solar cells, the new design showed optimal performance when manufactured at 450 °C,