| Work Detail |
A German research team has developed a precise cleaning process for electrode deburring in perovskite and organic solar PV roll-to-roll production lines. It is based on commercially available equipment from Germany-based Acp Systems.
German researchers have developed a process to remove conductive burrs on perovskite and organic PV substrates that can be integrated into roll-to-roll production lines. It is based on an automated liquid carbon dioxide-based snow-jet cleaning system made by Acp Systems, a German industrial equipment manufacturer.
The deburring process emerged from a project called PV-CO2. The research team explained the rationale for the research in a technical article published by Acp Systems. It explained that conductive burrs can form after laser structuring of front electrodes of perovskite solar cells and organic PV (OPV) substrates.
The burrs protrude just a few micrometers, and if they are not removed, there is a risk of damage and short circuits. “The current practice is to remove the burrs mechanically at very low web speeds. However, there is a risk of the structured layers becoming damaged due to the mechanical impact,” said the researchers.
To develop a more precise, automated, and dry deburring step, the team applied Acp Systems’ Quattroclean snow-jet cleaning technology. It is a solvent-free, dry process based on liquid carbon dioxide (CO2) in a compressed air jet system, which can be used for either full-surface or selective cleaning.
“Thanks to the dry process, components and assemblies that must not come into contact with moisture can also be cleaned,” Acp Systems’ research engineer, Jonas Illg, told pv magazine. “In addition, the cleaning process with Quattroclean snow blast technology can be easily automated, integrated into fully automated production processes and monitored.”
Liquid CO2 is the cleaning medium, which Acp sources from recycled chemical and biomass energy production processes. It is guided and accelerated through wear-free two-substance ring nozzles and mixed with compressed air to CO2 snow crystal jets on exit. Once they hit the surface to be cleaned, it causes a combination of thermal, mechanical, sublimation and solvent effects to occur, which is the basis of the cleaning action, according to the manufacturer.
The snow-jet cleaning technology is already in use in other industries, such as electronics and semiconductor fabrication, battery production, coating and painting systems, as well as in medical device production, according to Acp Systems’ Illg.
The experimental setup
To fine-tune the process for the insulator-metal-insulator (IMI) substrates with an indium tin oxide, silver, indium tin oxide composition used to make perovskite and OPV devices, the researchers fitted several snow-jet nozzles above the web in a roll-to-roll R&D line. Then they fabricated an 8 cm-wide OPV module. One set of OPV modules was made on the IMI substrates that had been cleaned with an appropriately calibrated and programmed snow jet process, one set was manually cleaned, while the other was not cleaned.
The researchers found that the modules cleaned using the CO2 process had 5.3% power conversion efficiency. The manually cleaned sample modules had 4.8% efficiency, while those made with an uncleaned substrate “had a high leakage current,” which reduced efficiency to 2.3%.
Dark lock-in thermography was used to confirm that deburring is responsible for the outperformance of the cleaned samples. The researchers said that the difference in efficiency is attributed to scratches formed during manual cleaning, which significantly reduce the active area creating dead zones that do not generate any current, or that are cut off from the charge extraction.
In the meantime, a snow jet cleaning tool with seven nozzles has been integrated into an automated PV line with a 25 cm-wide web at the Institute Materials for Electronics and Energy Technology, at Friedrich-Alexander Universität Erlangen-Nürnberg (FAU). It has also been integrated into a roll-to-roll tool from German R&D equipment supplier Sciprios.
The PV-CO2 consortium included researchers from the FAU, Acp Systems, and Sciprios. It was funded by funded by the German Federal Ministry for Economic Affairs and Climate Action (BMWK).
Acp Systems was founded in 1997. Its core technologies include the Quattroclean snow-jet cleaning, high-precision microdosing and smart handling solutions for foils and flexible materials. |
