Openings IIT Centres IIT@POLIMI PhD at the Center for Nano Science and Technology of IIT@POLIMI in Milan (I)
| PhD at the Center for Nano Science and Technology of IIT@POLIMI in Milan (I) |
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CNST offers PhD thesis on the following projects: A) Charge transport and injection in high mobility, solution-processed organic semiconductors / Plastic electronics (1,2). The technological interest for solution-processed organic field-effect transistors (OFETs) has been steadily increasing in the recent past because of the demonstration of devices with mobilities higher than amorphous silicon. Yet fundamental aspects of the charge injection and transport mechanisms have to be fully understood, a mandatory requirement for the further development of this field. Research projects 1,2 are in this area. B) Organic opto-electronic devices (3,4). Molecular carbon based semiconductors have established a solid technology in the field of OLED, for display and lighting, as well in industrial coatings and bio-sensing. Coupled to non conventional techniques such as ink jet printing they offer alternative solution to a variety of technological challenges. The development of new opportunities for application rest on extensive fundamental research and some development, aimed at inventing, exploring and exploiting new phenomena and properties. Research projects 3,4 are in this area. C) Photophysics of nanostructures for photovoltaic conversion and other photonic applications (5,7,8). The quantum confinement of electronic states leads to large oscillator strength for optical transitions which enhance light-matter interaction and offer a handle for controlling linear and non linear optical properties. The study of photophysical phenomena in nanostructure requires advanced and broad characterization techniques, including time resolved spectroscopy from fs to ms, space resolved spectroscopy and opto-electronic probing such as photoconductivity and STARK spectroscopy. Research projects 5,7,8 are in this area.
D) Growth of nanostructured inorganic substrate and active layers for photovoltaic applications (9). This activity aims at developing an efficient, large scale deposition process for nanostructured thin films and nanoparticles of oxides and semiconductors. 1) The quest for ohmic contacts in OFETs Ref.: Mario Caironi and Dario Natali. Contact resistance effects are one of the opened issues for the downscaling of OFETs and the widespread development of plastic electronics. Although several approaches have been proposed to minimize them, a general solution to achieve ohmic contacts has not been discovered yet. Local doping, which is commonly adopted in silicon transistors, could be the answer, but given the difficulty of its implementation in organic semiconductors, it has been regarded as the holy-grail. This challenging project is aimed at investigating viable approaches for the realization of ohmic contacts in OFETs. Local doping achieved by the insertion of non diffusive dopants, as well as organic or hybrid interlayers and the exploitation of advantageous architectures will be pursued. 2) High resolution mapping of charge density in organic field-effect transistors by means of confocal charge-modulation spectroscopy Ref.: Mario Caironi and Calogero Sciascia Charge transport mechanism in organic semiconductors is still subject of debate. A direct observation of charge density within the channel of a transistor at different bias voltage and its correlation to materials morphology and electronic properties could help to shine light on the subject. Charge carriers in organic semiconductors show typical polaronic optical transitions that can be detected in charge modulation-spectroscopy (CMS) experiments. By combining CMS with a confocal setup, a high resolution mapping of the charge density in OFETs can be achieved. This project aims to test and develop this powerful technique on different organic systems with the goal to obtain important information on the physics of charge transport in organic semiconductors and provide strong experimental evidence for the development of suitable models. 3) Printed organic active matrix for X-rays imaging application Ref.: Dario Natali and Mario Caironi The goal of the activities in this area is to develop a digital X-ray image sensor array, with the aim of replacing the slow, conventional film-based X-ray process with an instantly digitized X-ray image. Printed organic semiconductors nicely fit the requirement for light-weight and large-area devices, as needed for bio-medical applications (e.g. mammography). The strategy is to develop an organic photodetector, one of the main building blocks, with suitable sensitivity range, coupled to a scintillator. To do this and to fulfil the requirement for a cost-effective patterning of arrays on large-areas, additive printing techniques, such as inkjet printing have to be adopted and developed. The realization of an active matrix requires also the development of suitable addressing switches, such as transistors. Therefore effective architectures and techniques for the printing of OFETs have to be investigated with the final scope to integrate the detector and the switch in an active pixel to be uniformly replicated in a matrix. 4) Bio-inspired organic photodetectors array Ref. Maria Rosa Antognazza and Mario Caironi. The project concerns the realization of an organic photodetectors array, characterized by a not-uniform distribution of the pixels, closely resembling the arrangement of human photoreceptors inside the retina. This should ensure a high visual acuity and at the same time a huge field of view, with interesting applications in robotics, remote surveillance, image processing, color appearance science and biological sensing. For the realization of the variable geometry state-of-the art lithographic and ink-jet technologies will be considered; the device will be then extensively characterized in terms of its optoelectronic properties. Finally, the implementation of the visual sensor in a humanoid robot can be envisaged. 5) Photophysics of nanostructures for photovoltaic conversion Ref. Annamaria Petrozza. The PhD research project aims to investigate energy and charge transfer processes at organic/inorganic and fully organic interfaces in nanostructures for photovoltaic applications based on colloidal semiconductor nanocrystals, conjugated polymers and metal oxides of different nature. Combining the use of both advanced spectroscopic techniques such as time-resolved Photoluminescence and Photo-induced Absorption spectroscopy and electrical characterizations, light has to be shed on the fundamental working mechanisms of light harvesting and charge generation; devices structures will be designed, fabricated and optimized consequentially." 6) Bio-organic functional interfaces Ref. Maria Rosa Antognazza. The project concerns the demonstration of new methods for recording and stimulating the activity of in-vitro neural networks, and it will be carried out in strong collaboration with the Neuroscience and Brain Technologies Dept. of IIT (main quarter in Genova). Organic semiconductors will be directly interfaced to living tissues, serving as active materials for signal transduction, from the artificial to the biological world and vice versa. The employment of organic technology might help to overcome the limitations of existing devices, in terms of biocompatibility, electrode invasiveness, mechanical stiffness and spatial-temporal stimulation patterns. Innovative techniques for optical stimulation and recording will be explored as well. |
The main goal at CNST is to develop a scientific community, which has a critical mass to address research challenges in nano science and technology. Specifically, the CNST research project rests on two iit technology platforms: Energy and Smart materials. The existing synergy among groups dealing with material synthesis, growth, structural characterization, photophysics and also theoretical modeling and device applications offers a unique chance for addressing modern challenges in nanotechnology at full spectrum. PhD students are the indispensable driving force to achieve excellent results and recognition in the international scene, and to them we dedicate major efforts for training, motivating and supporting. Weakly based seminars allows a constant exchange of ideas and provide a rich set of tutorials to support education and research. Hiring is on competitive base, through the Politecnico di Milano application procedure (1), as explained below.