German researchers claim to have weakened the groove effects when using a grooved coating in the manufacture of perovskite solar cells. The results are said to be the most efficient solar cell built using this technology to date.
The slot die is a coating a process used to deposit thin and uniform films with limited material loss and low operating costs.
“Organic die coating is one of the most promising processes that enables sheet-to-sheet, continuous roll-to-roll coating, and solution-processable optoelectronic device technology such as organic electronic devices and polymer solar cells,” the team said. notes that industry commonly uses spin coating in the production of perovskite cells.
The researchers said something new precursor ink The method aims to prevent the so-called ribbing phenomena, which usually arise from slot-die perovskite solar devices, which introduce irregular shapes into the deposited wet perovskite films.
“Growing is a common phenomenon observed in downstream meniscus when the viscous and capillary forces between the ink, grooving nozzle, and substrate are out of balance,” they noted.
They adjusted the viscosity of the ink with acetonitrile (ACN) at a concentration of 46%. The compound served as a co-solvent for FAPbI3 thin film and improved its quality and layer homogeneity.
The German team used this technique in a small-area solar cell with a power conversion efficiency of 22.54%, which it says is the highest certified value for a gap-coated perovskite solar cell to date. The device also achieved an open-circuit voltage of 1.088 V and a short-circuit current of 24.9 mA cm2, and a fill factor of 83.1%. The German Fraunhofer ISE CalLab confirmed this result.
The team also built mini-modules with active areas of 12.7 cm2 and efficiency 17.1%.
“Encapsulated devices have been subjected to year-round outdoor robustness tests with continuous maximum power point monitoring, and it has been shown that these devices retain nearly 100% of their original performance during winter and spring, with significant performance degradation during the warm summer months,” the researchers said.
In the future, the researchers plan to scale the technology to larger device ranges and evaluate performance under various long-term exposure conditions.