Optical Control of Charge and Energy Transfer in Molecular Wires
Abstract
This investigation is focused on the development of semiconducting molecules (molecular wires) that allow light to control energy and charge flow on the nanometer length scale. The study examines carbon based p-conjugated diblock oligomers that have an electronic structure that is analogous to that of semiconductor electronic materials. The molecules have an offset in electronic energy states that creates a heterojunction that is analogous to a p/n junction in a silicon-based device that is used to convert light into electrical signals (photodiode). As a result, they behave as Òmolecular photodiodesÓ, allowing charge (or energy) movement only in one specific direction along the molecule. Moreover, the structure of the molecular wires is such that the color of the illuminating light can be used as a control element, allowing an input signal (excitation wavelength) to control the molecular device response (output). The properties of these molecules are investigated using time-resolved laser spectroscopy methods in solution and at the interfaces of n- and p-type metal oxide semiconductors. The focus of the experimental work is to understand in detail the relationship between molecular and electronic structure and properties toward the long term goal of developing a new class of semiconducting molecules which could be used to fabricate advanced electronic and optoelectronic devices that feature fundamental processing elements that are the size of single molecules. The research effort comprises two primary activities. One is focused on the design, synthesis and structural characterization of the molecular elements. Second, the molecular systems are investigated using advanced time-resolved and steady-state optical methods to characterize the structure and dynamics of the intermediates produced by optical excitation with wavelength photoselection. The overall objective of the proposed investigation is to understand and control excited state charge or energy (exciton) transport on the nanoscale. This is a basic research project and the primary expected outcome is the generation of new knowledge concerning excited state properties and light induced charge transfer in p-conjugated molecular wires. A broader expected outcome is to understand relationships between molecular/electronic structure and optoelectronic properties. These outcomes are relevant to advanced optoelectronic technologies needed for national defense, public health and the economy. The project is expected to result in 3 - 4 technical papers per year published in peer-reviewed technical journals and 1 Ð 2 technical presentations per year at scientific/technical conferences. The project participants will join the US workforce and thus the program will aid the development of human resources in STEM. The project addresses the goals of the Air Force Office of Scientific Research/Materials Chemistry program through the study of precisely synthesized oligomers that incorporate functional moieties that will allow optical control of charge- and energy flow on the nanoscale in organic materials and at organic molecular/inorganic semiconductor interfaces.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Aug 31, 2020
- Source ID
- W911NF2010301
Entities
People
- Kirk Sullivan Schanze
Organizations
- Army Contracting Command
- Office of the Secretary of Defense
- University of Texas at San Antonio