Roll-to-roll flexible solar thin-film with 10% efficiency

The researchers have already completed the most important production steps in one go, using a continuously running system. The next phase is to complete all the steps in the same system, which will make the manufacturing process considerably more efficient. The thin-film solar cells have already achieved 10.2% efficiency.

The goal is to produce fully integrated solar modules with even greater efficiency. Mass production could help to create a new generation of affordable, flexible photovoltaic (PV) thin-film modules.

ZSW uses a 12 m web-coating system. A temperature-resistant plastic polymer film called polyimide is used as the substrate. The film is 0.0025 cm thick and 30 cm wide.

“The unique feature of this web-coating system is that all coating steps take place simultaneously in the same vacuum,” explains Professor Michael Powalla, Board Member at ZSW and Head of the Photovoltaics Division.

“While the back contact is applied at one end of the system by means of cathode sputtering, the co-evaporation of the CIGS absorber and the deposition of the transparent front contact layer are located elsewhere in the system.”

In the current development stage, the molybdenum back contact, the four elements for the CIGS absorber and the zinc oxide window layers can be deposited. The development and integration of a new buffer layer is still in progress. The monolithic cell interconnection will also be fully integrated at a later point in time.