Ultrathin Films of Room Temperature Ionic Liquids and Two Dimensional Layered Perovskites- Ultrafast Infrared and Vis-UV Experiments
Abstract
Room Temperature Ionic Liquids (ILs) and 2D layered perovskites are complex materials that are fundamentally interesting and important in current and future technological applications. ILs are composed of bulky organic cations and either organic or inorganic anions. The delocalization of charge among atoms of large cations and anions and their asymmetries reduces IL melting points below room temperature. In many of applications, such as electrolytes in batteries and thrusters for space craft, the IL is in contact with a surface that changes it properties on length scales from a few tens of nanometers to hundreds of nanometers from those in the bulk liquid. Contact with an interface modifies both the structures and dynamics of the ILs. We are using sequences of ultrafast infrared (IR) pulses to investigate the structural dynamics of IL thin films. We are determining how the ions that compose the ILs and the nature of the surface influence key IL properties. Perovskites are crystals generally having lattices made up of both inorganic ions and organic ions. Three-dimensional (3D) lead halide perovskites have attracted a great deal of interest for their applications in solar cells. Recently, two dimensional (2D) perovskites have been developed. 2D perovskites have 2D layers with organic or inorganic ions between the layers. 2D perovskites tend to be more stable and have better optical properties than their 3D counter parts. They are being used and developed for applications such as white light sources, light-emitting diodes, solar cells, photodetectors, and lasers. The key issues for understanding and developing 2D perovskites is the interplay between their electronic excited states (excitons and charge carriers) and their lattice dynamics. We are using ultrafast IR experiments, ultrafast visible experiments, and combined visible and IR experiments to directly study lattice structural dynamics and how these dynamics affect the electronic excited states.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Feb 06, 2025
- Source ID
- FA95502410145
Entities
People
- Michael D. Fayer
Organizations
- Air Force Office of Scientific Research
- Stanford University
- United States Air Force