Carrier Dynamics and Charge Transport in Soft Semiconductors
Abstract
Metal halide perovskites (MHPs) are an intriguing class of materials that have demonstrated excellent potential for use in a wide range of advanced devices including photovoltaics, photodetectors and radiation detectors. The atoms in MHPs are arranged in crystalline lattices, which are much more flexible than the lattices of semiconductors such as silicon or gallium arsenide that are widely used in todayÕs electronics, can easily deform when charges are present due to electric forces. Formation of a ÒpolaronÓ Ð a charge carrier and the associated nearby lattice deformation Ð can dramatically slow down the rate at which charges recombine with charges of the opposite sign, due to electrical screening effects, and the speed at which charges move through materials. The first research objective of this proposed research is to determine how MHPs composition affects polaron formation and properties. We proposed to synthesize a series of MHPs with varying metal, halide and cation compositions and measure the formation time of polarons, as well as carrier lifetimes and mobilities, using time resolved terahertz spectroscopy. Measurements will be performed at different temperatures. The second research objective is to examine the impact of spatially varying compositions and microstructure on polarons, carrier lifetimes and charge transport in MHPs. MHPs are typically grown in thin films composed of small grains, with compositions that can vary within and between grains. We proposed to use a series of different experimental techniques to characterize compositional inhomogeneity over nanometer to centimeter length scales, and to correlate these inhomogeneities with changes in polaron-mediated carrier dynamics and charge transport. This proposed research will also lead to enahnced research capabilities at NCCU, as new experimental setups are constructed and tested, that increase the universityÕs ability to contribute to the future research needs of the Department of Defense. Finally, the proposed research will engage NCCU undergraduate and graduate students in research on novel materials using cutting edge tools and techniques, and thus help broaden the pool of scientists capable of addressing upcoming technical challenges.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- May 24, 2023
- Source ID
- W911NF2310222
Entities
People
- Marvin Wu
Organizations
- Army Contracting Command
- North Carolina College
- Office of the Secretary of Defense