EPSCoR Track 1

RFA 1: Infrared Organic Optoelectronic Materials & Technologies

Advancing the State of Knowledge

RFA1 will develop the fundamental chemistry and physics to produce new materials, soft matter systems, and device paradigms enabling optical to electrical transduction of infrared (IR) light using organic semiconductors (OSCs). Through the development of modular synthetic approaches, we demonstrated the first example of precise control of conjugated polymers in the IR spectral regions. Such synthetic control has also resulted in the development of materials with complex and tunable electronic structures, varying magnitudes of intramolecular electron-electron pairing, cooperative electronic properties based on π-electrons, and controlled spin alignments; design paradigms which underlie the development of next generation optoelectronic technologies. The discontinuity in the structure and dynamics of these materials as the bandgap continues to narrow is a manifestation of increasing electron correlations and, similar to their inorganic counterparts, leads to new emergent properties. Furthermore, these materials are multiscale in their characteristic energy, length, and time scales and fundamental excitations span the ultraviolet-visible-IR (intra- and intermolecular excited state transitions) and microwave (between different spin states). A lack of IR-absorbing polymers has precluded in-depth investigations of various phenomena in low bandgap systems and excluded the use of conjugated polymers (CPs) beyond the NIR. It is critical that the properties of these materials are carefully controlled and investigated in order to enable the desired optoelectronic functionality. These studies will be the first of their kind that detail general design rules for incorporating CPs into IR optoelectronics, articulate specific challenges associated with these materials, and that connect intrinsic properties with device performance.

IR photoresponsive OSCs will exhibit completely new properties in relation to existing semiconductor materials. Extending the photoresponse of OSCs into new spectral regions will enable new technologies. IR photoresponsive devices based on OSCs will serve as the basic building blocks for more advanced optoelectronic technologies, supersede traditional IR photodetection and energy conversion paradigms with lower cost, higher performing devices that use excitons (bound state of an electron and hole) to mediate the flow of energy. Research objectives and tasks (defined below) have been developed to address the following research questions:

• What are the electronic and physical interactions, determined by orientation, interchain packing, and ensemble structure that will enable bandgap and electronic structure control in the IR in diverse materials sets?
• Using a combination of theory-guided chemical design, synthesis, and characterization, how do we establish a fundamental understanding of the interrelation between molecular and solid-state structure on exciton formation, lifetime, dissipation, and coherence?
• What are the underlying physical and chemical principles of function and how can we establish conceptual designs for new molecules and materials?
• Using our established design rules and systematic approaches is it possible to enable efficient charge photogeneration in progressively narrow bandgap and strongly correlated organic materials?
• How do OSCs fundamentally interact with IR light? What new photophysical phenomena and properties are available and how can they be translated into devices?

Goals and Objectives

GOAL 1: DEVELOP NARROW BANDGAP AND INFRARED PHOTORESPONSIVE ORGANIC SEMICONDUCTORS AND FABRICATE AND ENGINEER PHOTORESPONSIVE DEVICES THAT OPERATE IN VARIOUS INFRARED SPECTRAL REGIONS.

• Objective 1.1: Synthesize Materials: Establish Energy Level & Bandgap Control
• Objective 1.2: Carry out Photophysical Investigations & Engineer Excited State Properties
• Objective 1.3: Fabricate & Engineer Infrared Photoresponsive Devices

Research Team and Affiliation

JACKSON STATE UNIVERSITY:

Qilin Dai
Glake Hill
Jerzy Leszczynski

MISSISSIPPI STATE UNIVERSITY:

Santanu Kundu
Dong Meng
Neeraj Rai

UNIVERSITY OF MISSISSIPPI:

Jared Delcamp
Nathan Hammer
Jonah Jurss
Davita Watkins

UNIVERSITY OF SOUTHERN MISSISSIPPI:

Jason Azoulay
Xiaodan Gu
Sarah Morgan
Yoan Simon

RFA 2: Multifunctional Macromolecular Materials with Tunable Electronic Structures

Advancing the State of Knowledge

RFA2 will develop the fundamental science of charge neutral, π-conjugated, macromolecular chemistries with tunable open-shell configurations.  Organic macromolecules are particularly appealing candidates to replace and/or complement traditional semiconducting materials in devices and are being used as building blocks of new optoelectronic devices (organic thin film transistors, organic light-emitting diodes (OLEDs), solar cells, and photonic devices). Non-linear optics, where optical properties of materials depend on the intensity of light, is one such example where there is an intense research effort currently underway. However, to realize this immense potential, we need to have a better understanding of how molecular structures (motifs) alter the electronic structure of macromolecules. This RFA utilizes exhaustive and detailed computational and state-of-the-art characterization tools to pin down structure property relationships to establish design rules for identifying molecular features for specific optoelectronic applications. One of the unifying theoretical concepts at the heart of these properties is the diradical character (which is a measure of the degree of open-shell character (unpaired electrons) see RFA2 Overview Figure).

The RFA2 effort will afford the rational development of materials with complex and tunable electronic structures, varying magnitudes of intramolecular electron-electron pairing, cooperative electronic properties based on π-electrons, and controlled spin alignments; design paradigms which underlie the development of next generation optoelectronic technologies. Synthetic control of these features will impart varying degrees of, and distinct, optical, electronic, spin, magnetic, transient, and multifunctional activities not possible with other semiconductor materials. Research objectives and tasks (defined below) have been developed to address the following research questions:

• What are the molecular, electronic, and solid-state requirements for the adaptation of various ground state (GS) electronic configurations (aromatic, quinoidal, biradicaloid, polyradicaloid, high-spin)? How can these be applied to diverse materials systems?
• What factors govern the magnitude of intramolecular electron-electron pairing in тт-extended biradicaloids and lead to unique optical, NLO electrical, transient, spin, and magnetic properties?
• How do we control spin alignments and manipulate the energies between these states to access truly stable, high spin OSCs? Is the total spin (S) a function of systems with more than two “sites” for unpaired electrons and what effect will radical delocalization have on spin coupling (J) in extended systems? To what extent can J be tuned? How do we use anisotropic, hierarchical, and supramolecular structures to influence S and J?
• What new phenomena and properties are available, to what degree can they be controlled, and how can they be translated into devices?
• Can powerful computational approaches be developed, through experimental benchmarking, to make use of the collective properties of conjugated тт-electrons as a design paradigm to access long range electronic, structural, magnetic, excited, coherent, and quantum states?

Goals and Objectives

GOAL 2: SYNTHESIZE CHARGE NEUTRAL, PI-CONJUGATED, MACROMOLECULAR CHEMISTRIES WITH TUNABLE OPEN-SHELL CONFIGURATIONS AND ESTABLISH THEORETICAL BASIS FOR PREDICTING PROPERTIES

• Objective 2.1: Establish design rules for pi-extended open-shell organic macromolecular systems
• Objective 2.2: Quantify the role of diradical index on photophysical, electrical, magnetic, and spin properties

Research Team and Affiliation

JACKSON STATE UNIVERSITY:

Qilin Dai
Glake Hill
Jerzy Leszczynski

MISSISSIPPI STATE UNIVERSITY:

Santanu Kundu
Dong Meng
Neeraj Rai

UNIVERSITY OF MISSISSIPPI:

Jared Delcamp
Nathan Hammer
Jonah Jurss
Davita Watkins

UNIVERSITY OF SOUTHERN MISSISSIPPI:

Jason Azoulay
Xiaodan Gu
Sarah Morgan

RFA 3: Emergent Materials for Hybrid Organic/Inorganic Interfaces

Advancing the State of Knowledge

RFA3 will use the polymeric organic materials developed in RFA1 and RFA2 in systems with added inorganic components to introduce new properties such as prolonged excited-state lifetimes, prolonged photoinduced charge separation, and spin control. This RFA will probe how the use of progressively lower energy light will affect these properties. Many of these organic-inorganic systems are relatively well understood with small molecules and polymers absorbing visible light. However, in the NIR, SWIR, and MWIR regimes, these organic-inorganic interactions are not as well understood. As lower energy photons are used, significant changes in optical, spin, and charge separation properties are expected from these materials. The polymers being designed in RFA1 and RFA2 are uniquely well-suited to probe how changes in photon energy affect organic-inorganic materials heterostructure properties.

RFA3 will develop the fundamental chemistry, physics, materials science, and engineering to produce next-generation optoelectronic functionality and devices based on hybrid (organic-inorganic) heterostructures. The integration of organic semiconductors (OSCs) with tunable narrow bandgaps and unique electronic structures with inorganics will allow the rules that apply to matter and light to be further stretched, enable the design and realization of functions not available from the constituent materials, and seed completely new paradigms in optoelectronics. We will begin to elucidate the mechanisms governing the optical, transient, electronic, spin, magnetic, and correlated response arising from the interactions between the functional OSC and inorganic component. The properties of our materials can be controlled precisely, which has remained a persistent challenge for semiconducting materials with narrow bandgaps, such as carbon nanotubes (CNTs), 2D materials, transition metal dichalcogenides (TMDCs), colloidal quantum dots (CQD)s, inorganic nanocrystals (NCs), plasmonic nanoparticles (PNPs), perovskites, van der Waals heterostructures, and oxides.  Research objectives and tasks (defined below) have been developed to address the following research questions:

• How do we elucidate and control elementary excitations, dynamic processes, and electronic correlations at the complex interface between organic and inorganic materials?
• How do OSC electronic, physical, and morphological features impact neutral and charged excitations at the interface of inorganic nanomaterials?
• How do tailored covalent interfaces between OSCs and inorganic materials influence electronic coupling? How does interface composition affect properties?
• How do OSC structural, electronic, physical, morphological, and transient properties affect charge separation and carrier transport in hybrid systems at progressively narrow bandgaps?
• How do we control spin and manipulate the energies between open shell OSCs and inorganics? What new phenomena and properties are available and how can they be translated into devices?

Goals and Objectives

GOAL 3: ESTABLISH DESIGN RULES TO GUIDE DYNAMIC PROCESSES AT ORGANIC-INORGANIC INTERFACES WITH NEAR-INFRARED AND SHORT WAVELENGTH INFRARED PHOTONS.

• Objective 3.1: Make hybrid excitonic systems to generate organic-inorganic interfaces with materials optically active in the NIR or SWIR.
• Objective 3.2: Transduce NIR and IR light in hybrid organic-inorganic systems into different forms of energy.
• Objective 3.3: Establish theoretical approaches to predict complex interface induced phenomena and identify next generation target systems.
• Objective 3.4: Design systems to generate long-lived photoinduced charge separation across NIR/SWIR absorbing organic-metal oxide interfaces.

Research Team and Affiliation

JACKSON STATE UNIVERSITY:

Qilin Dai
Glake Hill
Jerzy Leszczynski

MISSISSIPPI STATE UNIVERSITY:

Santanu Kundu
Neeraj Rai

UNIVERSITY OF MISSISSIPPI:

Jared Delcamp
Nathan Hammer
Jonah Jurss
Greg Tschumper
Davita Watkins

UNIVERSITY OF SOUTHERN MISSISSIPPI:

Jason Azoulay
Xiaodan Gu
Sarah Morgan
Derek Patton
Yoan Simon

RFA 4: NIR-SWIR Emissive Materials for Bioimaging & Sensing

Advancing the State of Knowledge

RFA4 will develop a suite of NIR II/SWIR (1-2µm wavelengths) emissive materials that will enable breakthrough biosensing and imaging applications. To capitalize on the opportunities afforded by NIR II/SWIR bio-imaging, this RFA brings the expertise of a multidisciplinary team of material scientists, chemists, and biologists to establish a unique collection of compounds with the potential to transform research and diagnostics. Our approach is fundamentally distinguished by the utilization of modular approaches, new chemistries, and target molecules whose spectral properties can be precisely controlled and integrated with sensing modalities.  To facilitate practical implementation of NIR II/SWIR fluorophores, we will use computational methods to predict and propose candidates for experimental development of novel molecules and water-soluble polymers with low cytotoxicity and enhanced photostability.  These initial fluorescent targets will be covalently attached to biomacromolecules (i.e., proteins and antibodies) for biosensing applications. Further modifications to the molecular framework of these novel molecules will afford materials capable of responding to physiological relevant analytes.

The collection of materials developed in this RFA will overcome the limitations of conventional fluorescent and tomographic techniques, revolutionizing capabilities within diverse fields. The proposed research activities will span molecular design to testing of compounds in cell culture and animals. To establish the capacity of these materials, efforts will target properties of biological systems that will be of interest to both basic research and the clinic.

Research objectives and tasks (defined below) have been developed to address the following research questions:

• What are the electronic and physical interactions that will enable emission with high quantum efficiency in the NIR II/SWIR in small molecule and polymer fluorophores in biological systems? What are the extrinsic mechanisms associated with low efficiencies within these spectral regions in the context of biological/aqueous environments? What are the underlying physical and chemical principles that will lead to conceptual designs for new molecules and materials?
• What bioconjugation strategies can be used to attach NIR II/SWIR emissive material to proteins, DNA, lipids, etc. that retain the native structure of these biomolecules to create new capabilities for deploying biomarkers and expand multiplexing options?
• Can NIR II/SWIR materials be developed for biosensing? What are the molecular design considerations for generating molecules for detecting extracellular and intracellular analytes? Can a desired distribution in biological systems be achieved through molecular engineering?

Goals and Objectives

GOAL 4.1: DETERMINE THE EFFECTS OF MOLECULAR STRUCTURE AND ENVIRONMENT ON THE PHOTOPHYSICAL PROPERTIES OF NIR II/SWIR SMALL MOLECULE AND WATER-SOLUBLE POLYMER FLUOROPHORES TO ENABLE NEW DESIGN STRATEGIES FOR EMISSIVE MATERIALS.

• Objective 4.1.1: Establish predictive protocols to understand the effect of energy gap between the excited and ground state of NIR II/SWIR small molecule and polymer fluorophores.
• Objective 4.1.2: Establish predictive protocols to understand the presence of vibrational states in the surrounding matrix and their coupling with the excited electronic states as well as the role of environment on emitter stability and brightness.

GOAL 4.2: ESTABLISH BIOCONJUGATION STRATEGIES FOR CLASSES OF FLUOROPHORES WHICH EXHIBIT NON-OVERLAPPING NIR/SWIR EMISSION SIGNALS FOR BIOSENSING.

• Objective 4.2.1: Tune the emission bands of fluorophore materials based on target dyes for the NIR II/SWIR region.
• Objective 4.2.2: Develop and apply synthetic routes to covalently attach NIR II/SWIR fluorophores to biomacromolecules for biosensing applications.

GOAL 4.3: DESIGN NIR II/SWIR BIOPROBES FOR DUAL SENSING AND IMAGING.

• Objective 4.3.1: Synthesize NIR II/SWIR bioprobes capable of an “off/on” fluorescent emissive response to physiological relevant analyte.
• Objective 4.3.2: Synthesize NIR II/SWIR molecules with enhanced water solubility and cell-permeability.

Research Team and Affiliation

JACKSON STATE UNIVERSITY:

Glake Hill
Jerzy Leszczynski
Yongfeng Zhao

MISSISSIPPI STATE UNIVERSITY:

Colleen Scott

UNIVERSITY OF MISSISSIPPI:

Jared Delcamp
Nathan Hammer
Davita Watkins

UNIVERSITY OF SOUTHERN MISSISSIPPI:

Jason Azoulay
Alex Flynt
Sarah Morgan
Derek Patton