DURIP- ULTRAFAST LASER SYSTEM FOR MEASUREMENTS OF CHARGE CARRIER SEPARATION AND DYNAMICS IN PHOTOACTIVE HETEROJUNCTIONS
Abstract
An ultrafast, 7 mJ Ti:Sapphire Astrella-USP-1K laser system is requested with this DURIP grant for new, extreme ultraviolet (XUV) core level transient absorption measurements to probe the charge dynamics of photoactive junctions. The ability to study ultrafast, element-specific charge dynamics is crucial for understanding prototypical solid-state, complex photocatalytic and photovoltaic systems, the major working principle of which is photon absorption and charge separation between distinct layers. This research will provide a foundation of knowledge essential for future developments in photocatalytic and photovoltaic applications. An existing apparatus will be upgraded and merged with the requested laser system to perform transient XUV absorption experiments, so that the dynamics of charges across materials can be characterized on few-femtosecond timescales. The equipment will contribute to a recently funded grant under AFOSR program manager Dr. Michael Berman, FA9550-19-1-0314, entitled “Ultrafast XUV Probing of Electron Dynamics at Photocatalytic Surfaces and Junctions”. Scientifically, this procurement will provide two major improvements to the existing equipment and the AFSOR program: (I) generation of sufficient flux for few-femtosecond XUV transient absorption measurements with excellent signal-to-noise ratio, and (II) investigation of photocatalytic and photovoltaic multi-layer systems by means of a few-femtosecond core level absorption technique. Namely, the electron and hole charge state dynamics, charge transfer, separation, and trapping will be investigated in semiconductor-semiconductor junctions, hybrid semiconductor-two-dimensional nonmetal material layered systems and, finally, dimensional nanostructured multi-material interfaces. With the proposed equipment a deeper understanding of different pathways to control charge transfer, charge separation, and band alignment will be explored and acquired. The experimental setup will allow for the novel study of short time, material-resolved charge dynamics in solid-state systems and will be a cutting-edge, knowledge spreading platform used to advance the stated research initiatives as well as to build the next generation of scientists. Students involved in the project will acquire qualifications in ultra-high vacuum instrument design, ultrafast and nonlinear optics, charge dynamics, and materials science essential for understanding principles of photocatalysis and photovoltaics, which are essential for sustaining future innovations in the area of renewable and sustainable energy.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Apr 20, 2023
- Source ID
- FA95502210451
Entities
People
- Stephen R. Leone
Organizations
- Air Force Office of Scientific Research
- United States Air Force
- University of California Regents