Discipline: Chemistry and Chemical Sciences
Subcategory: Chemistry (not Biochemistry)
Mark Kevin Garcia - University of Washington-Seattle
Co-Author(s): Gabriella Tosado and Qiuming Yu, University of Washington-Seattle
Research about perovskite-based solar cells have are being conducted because of their flexibility, lower manufacturing energy cost, and potential to replace traditional silicon-based solar cells. Within a six-year timespan, the efficiency of perovskite-based cells increased from less than 10% to more than 20%, making their efficiency comparable to silicon-based cells’ efficiency (Correa-Baena et al., 2017). Despite the significant increase in the efficiency of perovskite-based solar cells, their instability prevents them from replacing silicon-based cells and from being manufactured for daily use. Using zinc oxide (ZnO) as an electron transport layer (ETL) in a solar cell deprotonates the methylammonium (MA) in the perovskite layer, which leads to the instability of the solar cell (Yang et al., 2015). We attempted to prevent or slow down the degradation of the perovskite by placing a silane layer (comprised of silane molecules diluted in isopropanol) between the ETL and the perovskite layer. We hypothesized that adding this thin barrier would make it more difficult for the ZnO to deprotonate the MA. To test this hypothesis, glass substrates were spin-coated with diluted ZnO, which were synthesized using protocols that were modified from previous research (Liu and Kelly, 2014). Substrates of the experiment set-ups were immersed in diluted (3 chloropropyl)trimethoxysilane or (3-aminopropyl)trimethoxysilane for 60 minutes to create a thin silane layer that is less than <10 nm thick. Substrates of both control and experimental set-ups were spin-coated with toluene and a perovskite solution with varying amounts of cesium iodide (CsI) (0%, 5%, 10%, and 15%) or tin (II) iodide (SnI2) (10%, 40%, and 60%) and were annealed at 100?C. For the perovskites with Cs, the appearance and intensity of yellow spots signs of degradation in the substrates were reduced when a silane layer was added. However, for the perovskites with Sn, none of the perovskites turned yellow after annealing at the same time and temperature. From these results, it can be concluded that the silane effectively stabilized the perovskites containing Cs. No clear conclusion can be stated about the effectivess of silane in stabilizing the perovskites with Sn; although the perovskites with Sn were more stable, it was not clear if the increase in stability was due to the silane or the Sn. This research, and more research into the molecular interactions at the interface between the silane and the perovskite layer will further add to our understanding of the microscopic interactions. This will allow us to devise ways to make perovskite-based solar cells more stable and therefore practical for daily use.ERN Conference.docx
Funder Acknowledgement(s): This material is based in part upon work supported by the State of Washington through the University of Washington Clean Energy Institute and via funding from the Washington Research Foundation.
Faculty Advisor: Gabriella Tosado, email@example.com
Role: I synthesized zinc oxide and different perovskite solutions. I fabricated the zinc oxide electron transport layer, silane layer (for the experimental set-up), and the perovskite layer. I annealed the substrates and recorded observations.