A method to create extra efficient narrow bandgap (NBG) perovskite films for tandem solar cells

• All-perovskite tandem solar cells, solar cells included stacked wide-bandgap (WBG) and also narrow-bandgap (NBG) perovskites, could be especially appealing energy services. Contrasted to other existing solar systems, these cells could accomplish excellent energy-efficiencies while significantly decreasing fabrication prices.

Researchers at University of North Carolina at Chapell Hill and University of Rochester have actually recently developed a new hot gas-assisted method that can boost the fabrication of NBG perovskite films for tandem solar cells. This technique combined with an anti-oxidation product included the film, both of which were presented in a paper released in Nature Energy, can increase the solar cells' carrier recombination lifetime (i.e., the moment it considers excess cost carriers to degeneration).

" All-perovskite tandem perovskite solar cells are guaranteeing to minimize the expense of solar systems, because of their prospective to reach a much higher effectiveness than their single-junction counterparts, while preserving the solution fabrication procedures," Jinsong Huang, among the scientists who carried out the study, told TechXplore. "Likewise, compared to single junction perovskite modules, the application of tandem structures, which have a lot smaller sized photocurrents but greater photovoltage, can likewise minimize the cell-to-module performance derate, as well as therefore make it possible for the awareness of higher module effectiveness for monolithically interconnected modules in a series."

In all-perovskite tandem solar cells, both the WBG and NBG perovskite layers are transferred using a technique called blade coating. Blade coating, likewise called knife coating or doctor blading, is a scalable coating technique that involves applying an unwanted of coating material to a substratum and then removing some utilizing a blade, until one gets to the desired coating.

Huang as well as his colleagues developed a new blade coating strategy that could be specifically favorable for the fabrication of NBG perovskite films. In contrast with various other commonly used techniques, their strategy utilizes a hot gas.

" To produce our NBG perovskite films, we established a hot gas-assisted blade coating technique to achieve premium, large-area, and thick films," Huang stated. "The hot gas accelerated the drying out of the high boiling point solvents to strengthen the as-coated wet film, preventing the microscale solution moves. Furthermore, a minimizing agent benzylhydrazine hydrochloride (BHC) was introduced to avoid Sn2+ as well as iodide oxidization during film deposition and, extra importantly, to withstand the air direct exposure throughout module fabrication."

Using their new blade coating approach, Huang and also his colleagues had the ability to suppress undesirable processes taking place throughout the coating of their NBG perovskite film. The resulting film was after that used to produce all-perovskite tandem solar cells with an amazing efficiency of 21.6%, with a 14.3 cm2 aperture area, which corresponded to an energetic location performance of 23%.

" Our ingenious hot-gas assisted blade coating method enables the high-throughput fabrication of huge location, excellent quality NBG films for all-perovskite tandem solar cells," Huang included. "On the other hand, scaling up all-perovskite tandem solar modules is challenging because of the degradation of the slim band void subcell throughout module handling in an ambient problem. In this work, the minimizing representative BHC makes it possible for module fabrication in an ambient atmosphere, which is a crucial step toward automation."

In the future, the current work by this team of researchers can contribute to the automation and also up-scaling of reliable all-perovskite tandem solar cells that are more affordable. At the same time, the scientists prepare to utilize their technique to create much more reliable and steady solar modules with bigger surface areas.