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Projects / Programmes source: ARIS

Organic-inorganic thin film structures for electronics components

Research activity

Code Science Field Subfield
2.09.05  Engineering sciences and technologies  Electronic components and technologies  Vacuum technologies 

Code Science Field
T001  Technological sciences  Electronics and Electrical technology 

Code Science Field
2.02  Engineering and Technology  Electrical engineering, Electronic engineering, Information engineering 
Keywords
Thin organic films, organic semiconductors, organic/metal interface, multilayers Thin organic films, organic semiconductors, organic/metal interface, multilayers Thin organic films, organic semiconductors, organic/metal interface, multilayers
Evaluation (rules)
source: COBISS
Researchers (10)
no. Code Name and surname Research area Role Period No. of publicationsNo. of publications
1.  23565  PhD Gregor Bavdek  Physics  Researcher  2011 - 2014  84 
2.  11546  PhD Dean Cvetko  Physics  Researcher  2011 - 2014  207 
3.  18635  Tatjana Filipič    Technical associate  2011 - 2014  24 
4.  29515  PhD Gregor Kladnik  Physics  Researcher  2011 - 2013  77 
5.  15703  PhD Janez Kovač  Electronic components and technologies  Head  2011 - 2014  679 
6.  10429  PhD Miran Mozetič  Electronic components and technologies  Researcher  2011 - 2014  1,354 
7.  09090  PhD Peter Panjan  Materials science and technology  Researcher  2011 - 2014  792 
8.  09105  Borut Praček  Electronic components and technologies  Researcher  2011 - 2013  113 
9.  36727  Janez Rihtar  Physics  Researcher  2014 
10.  20335  PhD Bojan Zajec  Civil engineering  Researcher  2011 - 2012  183 
Organisations (2)
no. Code Research organisation City Registration number No. of publicationsNo. of publications
1.  0106  Jožef Stefan Institute  Ljubljana  5051606000  91,025 
2.  1554  University of Ljubljana, Faculty of Mathematics and Physics  Ljubljana  1627007  34,298 
Abstract
Electronic devices based on organic materials attract much attention in several applications (e.g. illumination devices, color digital displays, photovoltaic elements, sensors, lasers…) due to their lower production and processing costs comparing to conventional semiconductors. The advantage of hybrid organic-inorganic elements is to keep and enhance the best properties of both materials and reduce their particular limitations. The availability of a rather large set of different organic molecules offers a possibility to tune the desired electronic characteristics with suitable chemical properties in such elements. The electric transport properties of organoelectronic devices are determined by the organic/metal interface. The strong interaction between the ? molecular orbital and the charge density of the metal electrodes drives a reorientation of the molecules at the interface. This often prevents the organic molecules from growing with their crystal orientation, which deteriorates the electronic properties (carrier mobility) of the organo-electronic device. As a consequence in organic photovoltaic cells, for example, this effect is related with low solar energy conversion efficiency. The aim of our project is to overcome this drawback in two ways. The first is based on introduction of an intermediate self assembled monolayer of organic molecules as a buffer layer, and growing the second semiconductor organic layer on top of it. This may be a viable route to reduce the effects of strain at the interfaces and improve electronic transport characteristic. Electronic and optical properties of the organic devices depend on the degree of conjugation of the aromatic rings within the molecule and on the functional group capable to form covalent bond of SAM layer to metal surface. Therefore molecules with different functional groups like silanes, amine and carboxylate will be examined in the frame of the project as candidate for intermediate layer. The second proposed approach is based on the introduction of the multilayer structure of organic/organic or organic/inorganic layers of thickness up to some tens of nm. Organic materials used in our project will be from group of polyacenes, thiophenes perylene derivatives and fullerenes and will be prepared on metallic substrates Au, Ag or inorganic semiconductors.   Thin film and multiplayer structures will be prepared with vacuum techniques as evaporation and by wet-chemical techniques from solutions. The structures will be treated also by plasma and ion beams to functionalize surfaces.   Characterization of proposed structures will be performed by modern spectroscopic techniques XPS and SIMS, by microscopic techniques AFM and SEM and by measurements of charge transport characteristics in laboratories in Ljubljana. Complementary investigation will be performed at advanced synchrotron based instrumentation with methods as NEXAFS available at the ALOISA and TWINMIC beamlines at the Elettra synchrotron in Trieste in Italy.   In the frame of the proposed project we intend to answer to the following questions: what are relations between the chemical bonds, growth mode, electronic and geometric structures and dynamics of the charge transfer across the organic/substrate interface, what is the chemical and temperature stability of the such organic structures and what is an effect of treatment with ionized beams and plasma. Since the electronic devices have complex architecture we intend to prepare and characterize organic multilayer structures, in which an influence of different combinations of organic materials on transport and other properties of organic/organic interfaces will be studied.   We will estimate the possible applications of specific organic heterostructures in prototypic elements for organics electronics.
Significance for science
The results of the completed research project can provide several answers to fundamental issues of thin organic film formation on metallic substrates. Specifically, the role of intra molecular interaction as well organic film binding to the substrate have been explored throughout the initial stages of growth where, growth kinetics, interface energetics as well as size quantization play an important role. Our results elucidate the fundamental physics and chemistry involved in the organic/inorganic interface formation with a possible impact on the organic semiconductor technology. In particular we studied the introduction of an intermediate self-assembled monolayer of organic molecules as a buffer layer, and growing the second semiconductor organic layer on top of it. We showed that this is a viable route to reduce the effects of strain at the interfaces and improve electronic transport characteristic. Electronic and optical properties of the organic devices depend on the degree of conjugation of the aromatic rings within the molecule and on the functional group capable to form covalent bond of SAM layer to metal surface. Therefore molecules with different functional groups like silanes, amine and carboxylate were examined in the frame of the project. In the system of the model aromatic layer 1,4-benzenediamine (BDA) on Au substrate we studied transport dynamics of charge carriers over hybide interface as a function of a specific type of chemical bonding with organic molecule. Our results evidence, that contrary to general belief, ultrafast charge transfer across a hybrid junction does not require a covalently bonded system. In the heterogeneous organic multilayer of hexabenzocorone (HBC) and C60 layers we studied electronic coupling, level alignment and charge transfer rates at the heteroorganic interface. We showed that shape complementary of donor acceptor molecules in the heterojunction lead to improved efficiency of organic photovoltaic devices. We studied the role of intermolecular interactions on charge transfer in pi-stacked layers of cyclophanes and demonstrate that through-space charge transfer between aromatic rings depend strongly on the decreased inter-ring distance. We studied also the formation of new phases in multilayer system C/Si/C/Si/C which was induced by irradiation with ion beam, the thermal stability of metallic phtalocianes CuPC on the Au, Ag and Cu substrates and the early stages of Pb/Ge(001).
Significance for the country
A subject of the completed project is very actual and has many possible applications in the field of electronics components and materials, which is relatively well developed in Slovenia. Organic semiconductor structures may be produced on small scale and with high added value. In the future they will be used extensively for photovoltaic devices, for solar cells, lightening elements, transistor elements, sensors… Therefore the knowledge obtained within this project could contribute to introduction of new products in Slovenian industry of electronics components. Results of this project were published in several prestigious scientific journals with very high impact factor. In this way we promoted Slovenian science and our project group. Members of our research team presented the obtained results in a form of invited lectures at several international conferences and at foreign Universities. The research activities within this project had a strong impact on education and formation of young scientists and PhD students that have been included in the scientific formation, and have directly resulted in two PhD dissertations. Several BSc and Masters students have also been involved in the research activities related to this project of our laboratories. Within the performed project, part of the research activity was done in collaboration of Slovenian scientists with the Laboratory IOM-CNR and synchrotron light source Elettra in Trieste which is the worldwide unique research facility, which resulted in established scientific ties that will extend in the future, far beyond the completion of this project. During the course of this project a unique experimental technique in Slovenia i.e. Secondary ion mass spectroscopy (ToF-SIMS) was introduced and implemented in our laboratory, which is a very complex and advanced method for characterization of thin organic films and semiconducting substrates. The knowledge obtained in this project will be explored in further collaboration with Slovenian industrial partners either as service analyses or through joint projects.
Most important scientific results Annual report 2011, 2012, 2013, final report, complete report on dLib.si
Most important socioeconomically and culturally relevant results Annual report 2011, 2012, 2013, final report, complete report on dLib.si
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