Dr. Jeffrey Christians, Engineering
Halide perovskites offer exciting potential as photovoltaic materials and simply as semiconductors. Specifically, their structural tunability has become of greater interest as researchers begin to search for novel ways to tune the materials to achieve improved solar cell stability or to target new applications. One potential technology which halide perovskites could enable is dynamically switchable photovoltaic windows, windows which a user can transition between photovoltaically active (dark) and non-photovoltaic (transparent). We build toward this goal in this work by investigating the intercalation and deintercalation of methylamine gas into 2-dimensional Ruddlesden-Popper phase halide perovskites. As has been shown with methylammonium lead iodide films, the intercalation of methylamine into the halide perovskite lattice results in a color change to a clear crystal phase. We find that in some 2-D perovskite systems, deintercalation of the methylamine gas is incomplete, resulting in the formation of some CH3NH3PbI3; however, other 2-D perovskite phases show reversible intercalation/deintercalation with methylamine, indicating stronger binding between the long-chain ligand and the lead halide octahedra of the 2-D perovskite sheet. When integrated into a hybrid 2-D/3-D structure of the type A’2(CH3NH3)nPbnI3n+1, where A’ is a strongly binding R-NH3+ moiety such as phenethylammonium (PEA), these materials show promising reversibility for methylamine intercalation/deintercalation with little change in absorption or morphology. This work reveals the relative affinity of various R-NH3+ molecules for the halide perovskite lattice, showing that many of these are not replaced by methylamine, and indicates that templating the 3-D CH3NH3PbI3 structure with long-chain ammonium cations could lead to better reversibility in dynamic photovoltaic windows.
Repository citation: Cutlip, Elizabeth, "Interactions between 2D Halide Perovskite Materials and Methylamine" (2020). 19th Annual Celebration of Undergraduate Research and Creative Activity (2020). Paper 26.
April 17, 2020. Copyright © 2020 Hope College, Holland, Michigan.