Research Interests of the Carroll Group
When asked to describe his/her research efforts of foci, each researcher in the CRG would give a completely different answer. Motivators are as different as each person’s vision of the future. But major “memes and themes” can be imagined based on our recent track record of publications, talks, and ongoing experiments. And so we might say that one overarching theme of our research is to understand how fundamental symmetries and dimension of a material object plays a role in that object’s emergent quantum expression. For example, local topology and global geometric symmetries and boundaries can combine in some two-dimensional material manifolds, to require specific properties (broken symmetries) of their cooperative wavefunctions. In condensed matter physics, such systems can provide very deep insights into the quantum nature of our universe, when matter interacts cooperatively. But, they can also open the door to exciting new technology developments as well. In our group, we have both types of researchers: those that would understand the beauty of the symmetries and try to rewrite the textbooks, and those that would delve more deeply into the development of new technologies such as LEDs, PV, TEG, PEGs, etc, in an answer to the call of society’s critical need. Both of these are excellent descriptors of our group.
CarrollResearchGroup © 2018
Bio-electronics and Medicine
Our work in nanoMedicine has used novel nanomaterials to focus primarily on early clinical opportunities in cancer therapeutics, mobile and wearable biosensing, trauma diagnostics, approaches to antibiotic resistant organisms, and printable, smart tissue scaffolding. As we move forward however, our vision is to combine nanoengineered tissue scaffolds with semiconductor polymer circuits (based on our newly developed biocompatible conducting polymers) to achieve a synthesis of biological/technological function. This cybornetic or bioelectronic approach to the enhancement of the human experience promises to dramatically alter the nature of what we call “medicine.” (Kaplan)
Photovoltaics
We have multiple projects in Solar Power technology development. (Gray)
Development of new polymers for use in OPV
Our group continues to explore the design of new macromolecular nanocomposites for use in photon absorption. Using rational design methods based on simulations, we have focused on families of benzo-dithiophene containing polymers. Our goal is to better understand the origins of polymer electronic and optical properties and how to tune them to our needs in OPV.
3D optical architectures for very high efficiency solar collection
Three dimensional architectures do more than capture light like a black body; they provide avenues into nonlinear behavior. Our group first introduced FiberCell in 2007 after several years of development. From this simple device, of an OPV wrapped around an optical fiber, we have found that a large amount of new physics can arise. Currently we are engaged in understanding how the mode structure and confined fields of the 3D architecture can result in spectral overlap broadening, and exciplex enhancement for OPV.
Novel nonlinear optical elements for high efficiency solar
Typically, nonlinear optical processes such as frequency shifters and multiple exciton generation (MEGs) have such as low cross section that they are of little use in the low flux conditions of solar collection. However, in confined optical architectures they may make sense. In fact, we hope to show that they can mimic the role of spectral splitting seen in multiple heterostructure, inorganic devices which are the current high performers. Our focus has been on lead based quantum dots: PdS/PbSe, and frequency shifting phosphors.
New Inorganic Absorbers with enhanced processability
Along with more traditional absorbers such as micro/nano crystalline, thin film Si, the Carroll group is explore grain control and bandgap engineering in earth abundant quaternary compounds of Copper, Zinc, Tin, Sulfur - CZTS. We are particularly interested in grain growth, interface formation and stoichiometric stability. We also have a large effort in new hybrid Perovskites
Photovoltaic - thermal hybrids
As everyone knows, the big problem with photovoltaics is that they do not work at night (or on very cloudy days). The Carroll group has developed a number of hybrid systems that create electrical energy from BOTH the sun and ambient heat. But what are the limitations of these approaches? This program hopes to show that thermodynamic considerations lead naturally to avenues of efficient and cost effective PV-T.
Thermo/Piezo-Electrics
The focus of our power “scavenging” development is a meta-material platform with the form factor of a fabric and the ability to convert both kinetic and thermal energy into electricity. Moreover the intrinsic coupling of the kinetic energy scavenging with the thermal energy scavenging yields a synergistic effect which we have termed T-PEG (Thermo - Piezo electric power generation). Much of our recent effort has centered on the use of 2D dichalcogenides applied to this platform. Such systems have become known colloquially as “Powerfelt.” However, more generally they are predicted by Onsager’s relations and lead us to a deeper understanding of the interplay of coupled heat reservoirs in solid state heat engines. (Hewitt)
Lighting / Displays
Our “lighting” research focusses on the use of matrix nanocomposite organic emitters in OLED and newly developed FIPEL topologies. We have shown that internal symmetries and dimensionality of the nanophase can be used to “engineer” properties of the emitter’s excited states opening the possibility of super - efficiency illumination, optical amplification, dynamic color engineering, and novel lighting configurations. More recently we have published various works in Perovskite based LEDs. (Xu)
Quantum Materials
The creation of novel “materials structures” lies at the heart of our work. May applications in optics, electronics, and biotechnology require materials with properties that are not easily realized in nature. However, by integrating materials with different phenomenology, and creating links between the sub-components of these new structures, we can create a range of novel meta-materials with synergistic properties that may meet our needs.
Recently we have begun investigations of emergent systems, that is quantum systems with properties that arise from cooperative phenomena. These include bounded topological systems, time crystals, and systems with nonabelian excited states. Our goal is to understand the basic nature of symmetries in the emergent expression of phenomena and their deeper connection to information theory. (Carroll)