Foto del docente

Tobias Cramer

Professore associato

Dipartimento di Fisica e Astronomia "Augusto Righi"

Settore scientifico disciplinare: FIS/03 FISICA DELLA MATERIA

Temi di ricerca

Parole chiave: Trasferimento di Carica, Transistor a Film Sottile, Elettronica Flessibile, Bioelettronica, Sensori Microscopia a Forza Atomica

Charge transfer processes: The movement of a charge from a donor to an aceptor state is most crucial for many processes with enormous relevance in biology and information and communication technology. Although the materials involved in the process vary from molecules and proteins over polymers to crystals, a common theoretical framework with roots in quantum mechanics allows to describe the underlying physics. Most crucial for charge transfer processess is the coupling between the distribution of electronic charge and atomic coordinates, which results in polaron formation. The investigation of these states by theoretical and experimental methods in new materials and materials interfaces still holds the promise of unexpected findings and is of fundamental importance for many emerging nanoelectronic applications. (see for example T. Cramer et al. Phys Rev B 2015; K. Asadi et al. Nature Communications 2013; T. Cramer et al. Phys. Rev B 2009, L. Basiricò et al. Nature Communications 2016).

Charge transfer is the leitmotiv of my research activity. Appointments in different Universities and European Research Projects have further diversified my research interests in the past, currently my focus is set on:

Flexible and Stretchable Electronics: (see for example A. Campana, T. Cramer et al. Adv. Mat. 2014): Current electronic devices are confined to flat shapes and rigid form factors. Crystalline silicon allows for high-integration densities and fast computing architecture but it fails when electronic funtionalities have to be integrated on large, curved areas. Currently, material science is developing a range of new materials and composites that combine high performance semiconducting properties with a reduced elastic modulus giving rise to flexible or even stretchable behaviour. Such properties are of particular relevance for Bioelectronic sensors, energy harvesting, large-area photonic detectors. Investigation of the electromechanical properties of these new materials and the prediction of possible performance limits and unexplored opportuneties is part of my research activies. 

Organic Bioelectronics:(see for example Rand et al. Adv. Mat. 2018, T. Cramer et al. Chem. Mater. B 2013, T. Cramer et al. JAP 2012, T. Cramer et al. PCCP 2013). In this context I am active in the advisory board of the Bioel-Winterschool on Organic Bioelectronics in Austria.

Our nervous system employs electronic signals to control our body and to constitute our mind. Modern technology is making progress in interfacing these signals to trace the nervous activity and to influence it. The opportunety that such a technology offers is demonstrated by modern pacemakers or cochlear implants. Possible future applications regard artificial eyes, brain machine interfaces or electroceuticals. However, currently limitations arise from the high invasiveness and reduced sensitivity of bioelectronic interfaces based on traditional inorganic materials. In our research we investigate novel organic electronic materials that combine optoelectronic properties with high stability in the ionic environment of the body and biocompatibility. We develop experiments and models that provide a physical descriptions of how the electronic carriers in the materials interact with the ions in solution and ultimately lead to the formation of local electric fields, sufficient to ilicit neuronal activity and vice-versa. 

Atomic Force Microscopy:(see for example: T. Cramer et al. Scientific Reports 2016, S. Casalini et al. ACS nano 2015)

One of the major techniques that we employ to investigate electronic materials is atomic force microscopy. Beyond its well known capacity to map the surface topography of nanostructures we explore AFM to probe electrical and mechanial properties of materials and nanostructures at the highest possible spatial resolution. This experimental ability allows us to extend the understanding of how combined electromechanical effects impact for example on flexible electronics materials. AFM allows further to explore local surface conductivity  (conducting AFM) and local variations in the work-function (Kelvin Probe Microscopy). 

Innovative X-ray detectors and radiation hard electronics: (see for example T.Cramer et al. Adv. Elec. Mat. 2016, L. Basiricò et al. Nat. Commun. 2016)