An entire range of materials can be used today for solar cell production. Solar cells based on amorphous silicon, for instance, are thin transparent films that may be applied to any surface – including a window pane. When it comes to manufacturing solar cells, it is crucial to find ways to diminish light reflection from cells and avoid the overheating of transparent electrodes, which prevents the proper function of solar cells. Another key issues concerns the optimization of the active layers’ thickness, which is needed to ensure that each photon reaching the solar cell is turned into electricity.

Scientists from ITMO University devised a novel way to address these issues by putting droplet-shaped glass particles inside the top electrode. The resulting structure functions as an electrode as well as a light-trapping coating focusing the light on the solar cell.

“To create such structures on the surface of a solar cell, we use the method of atomic layer deposition of alumina zinc oxide. We literally build these electrodes atom by atom,” – explains Mikhail Omelyanovich, lead author of the paper – “As a result, overall solar cell efficiency is improved by 20%. What is more, such an electrode can be used for thin solar cells composed of any material beyond amorphous silicon.”

Mikhail Omelyanovich

It took the team several years to develop an affordable solar cell manufacturing method that would appeal to the industry.

“Three years ago we tried to cover the cell surface with microspheres. Despite improving light absorption significantly, a major drawback was their high reflectance rate. We considered removing the upper part of microspheres so as to make something similar to a lens that would focus the light on the solar cell. However, while working on the practical implementation of this idea we found a much better structure. On the whole, the final solution exceeded the expectations we’d based on theoretical calculations,” – says Omelyanovich.

According to the authors, the manufacturing of solar cells with such surface coatings does not require complex technology and the process may be easily adapted for mass production.

Reference: «Wide-angle light-trapping electrode for photovoltaic cells», Mikhail Omelyanovich and Constantin  Simovski Optics Letters Sep. 19, 2017