The scope of the present activity is the study, from the classical to the quantum level, of the fundamental processes involved in the motion of carriers (holes and electrons), lattice vibrations and other excitations in a large variety of materials and devices (including new generation solar cells, thermoelectrics, nanoelectromechanic devices, etc.) of interest for energy transport and conversion. For this purpose, different approaches will be available on the theoretical side, able to provide adequate description from the atomistic to the microscopic level, from quantum mechanics and ab initio approaches to molecular dynamics and modelling of strongly correlated materials. Both equilibrium and out-of-equilibrium phenomena (like the interplay of electronic and vibrational degrees of freedom in ultra-fast pump-and-probe experiments) will be object of investigation. The theoretical efforts will be accompanied by a continuous and fruitful comparison and interplay with the experimental results, as those provided, e.g., by angle-resolved photoemission, optical spectroscopy - both linear and non-linear - and nano-spectroscopies. Special focus will be given to novel two-dimensional and hybrid layered materials, and complex interfaces. The competencies available to the activity will also allow to get insights on nanocomposite materials and materials at the interface between biology and physics.
Activity Leader: Cantele Giovanni
State of art
The design and characterization of new functional materials for the development of new devices for energy transport and conversion is an emerging and rapidly developing research field. Basic interactions governing the fundamental processes in these materials are far from being understood, because electronic, lattice, spin and optical (photon) processes occur and can interfere with each other. Moreover, at the macroscopic level, other phenomena, such as the effects of energy exchange and scattering against the boundaries might take place.
The fundamental phenomena governing the response of such devices span a length scale that ranges from the nanoscale (nanodevices, nanoscale circuits, nanowires and nanotubes, two-dimensional materials, etc.) to the macroscale (composite materials, organic compounds, amorphous blends, etc.), so that their investigation requires a multi-scale approach and a variety of different competencies. For example, the matching of two different materials at an interface might not be described by just the knowledge of the electronic structures of the separated components, because structural reconstruction and charge transfer can show up. Typically, local chemistry effects (that is, phenomena induced by the formation of chemical bonds or by the interaction between the two different materials) require a microscopic description, that is, an atomistic point of view. On the other hand, elementary charge and spin excitations and transport require the elaboration of effective models, able to take into account the interplay between different degrees of freedom.
Emerging materials, such as graphene and two-dimensional crystals, topological insulators, semiconductors with helical and chiral edge states, hybrid organic-inorganic perovskite materials, layered compounds, nano- and micro-composites, and so on have been shown to be good candidates for energy and electronic applications, each with its own advantages and drawbacks. Driven quantum systems are also emerging as a valuable alternative in designing new and powerful microscopic devices with complex and rich thermodynamic behavior. These systems could offer the possibility to manipulate charge and heat on a quantum scale with numerous applications extending from quantum information to technological and biological device design.
In view of applications for low-power (nano)electronics, energy harvesting and conversion, and others, one needs a better understanding of heat production, and energy transport, dissipation and conversion from the quantum to the macroscopic scale.
Objectives
The main goal of the present activity is to provide a fundamental understanding of open problems in materials science, with a main focus on materials for nanoelectronics, energy harvesting and conversion, with special focus on phenomena where the interplay between different (electronic, vibrational, etc.) degrees of freedom as well as electronic correlations play a fundamental role. The many activities included within the present project are:
- to provide an atomistic description of complex nanostructures surfaces and heterostructures/interfaces, for the investigation of newly conceived systems with advanced functionalities. Typical examples are provided by van der Waal heterostructures, where many two-dimensional subunits can be interfaced with each other to provide efficient optoelectronic or (nano)electronic devices
- to provide a realistic and quantitative description of out-of-equilibrium (pump and probe) and ultrafast (~100 fs time scale) phenomena, involving at the same time electronic and vibrational degrees of freedom (for example, multiple exciton effects in two-dimensional layered materials)
- to provide accurate descriptions of transport coefficients such as conductance and thermopower of atomic and molecular junctions. The interest is on the role of many-body interactions between electronic and vibrational degrees of freedom. Focus is on the optimization of the thermoelectric figure of merit and the efficiency in conditions close to and out of equilibrium
- to elaborate accurate descriptions of equilibrium and out-of-equilibrium charge and spin transport in low-dimensional systems with novel properties (topological insulators and superconductors, spin-orbit-coupled quantum wires, etc.). Such systems can be envisioned as convenient tools to manipulate the spin degree of freedom, including the design of spin splitters
- to study complex out-of-equilibrium phenomena such as the dynamics of a quantum quench. Focus here is on the time evolution of a Hamiltonian quantum system after the modulation in time of one or few of its parameters. Such a study is strictly connected to the definition of the operation of the building blocks of a quantum computer
- to envision and propose new devices for the manipulation, transport and storage of energy in quantum systems. The purpose of this research activity is to quantify the influence of quantum dynamics on the energy transport in nano and quantum systems and to understand if and under which conditions these quantum effects can be exploited to build more efficient devices to manipulate the energy at quantum level
- to investigate the excitations of novel bulk materials, like the unconventional multiferroics, and of the two-dimensional electron gases which form at the interfaces and on the surface of topological insulators, by optical spectroscopy extended to the nanoscale
- to gain a better understanding of charge carrier fluctuation mechanisms in advanced functional materials, by resorting to additional and complementary experimental procedures such as noise spectroscopy
- to study and characterize field emission properties and interface barriers in novel nanoscale devices, with the aim of bringing out potential field emission applications and interface barrier tuning.
- to elaborate effective models and/or simulations of complex systems at the interface between material physics and biology. At this purpose, molecular dynamics and Montecarlo approaches will be available, that have already been proven to give efficient and accurate description of intriguing problems, such as laser-driven antibody−gold surface interactions of interest for biotechnological and biosensing applications
- to elaborate effective models, based on MonteCarlo and molecular dynamics simulations, of the thermoelectric efficiency in nanocomposite materials. In particular, phenomena of interest might be charge separation and transport at donor/acceptor interfaces and nanocomposites, currently employed in the development of new generation devices for energy harvesting and conversion
- to understand the structure and organization of complex biological systems systems, such as the structure and organization of chromosomes in mammalian cells from the subMb to chromosomal scales, by using polymer physics
Methodologies
- Ab initio density functional theory and its extensions
- Exact diagonalization techniques
- Montecarlo approaches and molecular dynamics
- World line quantum Montecarlo
- Analytical and numerical techniques to describe the out-of-equilibrium transport properties in nanosystems
- Advanced parallel numerical techniques for the solution of problems involving differential equations or large/sparse matrices
- Scattering matrix and non-equilibrium Green's function approaches
- Bosonization techniques
- Electric noise spectroscopy
- Infrared spectroscopy of two-dimensional electron gases in interfaces and topological insulators
- Atomic force micro-spectroscopy of inhomogeneous samples on the nanoscale
Main collaborations
- NTU Singapore
- CREST, Japan Science and Technology Agency (JST)
- CNR-NANO and Scuola Normale di Pisa, Pisa, Italy.
- Secondary collaborations:
- ETH, Zurich, Switzerland
- Aalto University, Helsinki, Finland
- Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Institut für Silizium Photovoltaik, Berlin, Germany
- University of Geneve, Switzerland
- University of Bonn, Germany
- Harvard university, Harvard, USA
- Laboratoire LPMMC, Grenoble, France
- Leibniz Institute for Solid State and Materials Research, Dresden, Germany
- Department of Inorganic and Physical Chemistry, Ghent University, Belgium
MAIN ONGOING PROJECTS
- CNR SPIN—NTU Singapore Joint Laboratory (Active 2015-2017): Amorphous materials for energy harvesting applications. The reasearch activity concerns the fundamental and applied investigation of new materials for environmental friendly energy harvesting devices, in particular in the field of thermoelectricity and photovoltaics
- CNR-SPIN—CNR-NANO: FIRB 2013 Project Coca (Active 2014-2017)
Project Coheat - Marie Curie Career Integration Grant (Active 2014-2018)
The projects and the research activities are focused on new ways to control, transfer and manipulate energy in quantum systems - FIRB CNR-SPIN— Federico II (Napoli)—Univ. Salerno. FIRB 2012 HybridNanoDev : Nanostrutture ibride superconduttore-semiconduttore: applicazioni nanoelettroniche, proprietà topologiche, correlazione e disordine (Active 2013-2016)
