Decreasing the width of PV metalization and interconnection fingers and busbars has long been exploited as an incremental pathway to higher cell and module efficiency. German researchers believe that light can be guided around the contacting structures, boosting efficiency.
The KIT researchers used a polymer coating that aligned with the contacting ribbons and fingers, deflected the light around the metal and onto the surface of the cell. The approach is similar to the one being developed for optical invisibility cloaking.
"Our model experiments have shown that the cloak layer makes the contact fingers nearly completely invisible," doctoral student Martin Schumann of the KIT Institute of Applied Physics, in an interview with Science Daily. Schumann carried out the experiments and simulations on the project.
The researchers used polymer coatings to refract the light. The coating that looks most promising for commercial application is a grooved coating that can refract light away from the contacts.
"When applying such a coating onto a real solar cell, optical losses via the contact fingers are supposed to be reduced and efficiency is assumed to be increased by up to 10%," said Schumann.
The initial KIT research was carried out using model experiments and simulations. The researchers are now going to apply the coating to solar cells for further experimentation.