Behind, João Pessoa city. Ahead, coral reefs at Picãozinho, 1,500 meters far from Tambaú beach. Foto: Cacio Murilo.
João Pessoa is the third Brazilian oldest city, being the capital of the state of Paraiba located in the Northeast of the country. It has a population about 770,000, while its metropolitan area comprises 8 satellite cities with 1,223,000 inhabitants. With a hot humid climate, João Pessoa has an average annual temperature around 26o C, reaching 29o C between September and October.
João Pessoa is known as the “Sun Door” or as “the city where the sun rises first”, having the easternmost point of Brazil. It has also a very beautiful sunset which can be admired at the sound of Ravel´s Bolero, in the “Praia do Jacaré”. It is also one of the greenest cities of the world, due to the presence of two reserves of Atlantic Forest inside the city.
João Pessoa has an important local culture. The architectonic-historic collection is very rich with baroque buildings from the XVI century, which worth a visit.
“Cabo Branco” Science, Culture and Art Station. Foto: Cacio Murilo.
Another touristic point is the “Cabo Branco” Science, Culture and Art Station, located at the easternmost point of the Americas (Ponta do Seixas), which is both an educational and cultural institution as well as a national landmark. The complex, inaugurated in 2008, was created by Brazilian architect Oscar Niemeyer and is one of his latest projects.
But the main touristic attractions of João Pessoa are its 18 beautiful beaches of green warm water – with a water average temperature of 28oC. Seven of these beaches are located in urban areas, with easy acces, very inviting for a nice swim.
We hope to see you at the XIII Brazilian Materials Research Society Meeting, held on 28 September to 02 October, 2014, in João Pessoa, PB, Brazil. This year the meeting has 2,141 accepted abstracts and, up to this moment, almost 2,000 inscriptions from Brazil and other 27 countries.
The XIII Meeting is comprised of 19 Symposia following the format used in tradicional meetings of Materials Research Societies, involving topics as synthesis of new materials, computer simulations, optical, magnetic and electronic properties, traditional materials as clays and cements, advanced metals, carbon and graphene nanostructures, nanomaterials for nanostructures, energy storage systems, composites, surface engineering and others. A novelty is a symposium dedicated to the innovation and technology transfer in materials research. The program also includes 7 Plenary Lectures presented by internationally renowned researchers.
This year, the B-MRS will present the results of two important actions from our society. The first one is the meeting of the B-MRS directory with the University Chapters (UC) already established and the students who want to establish other UC´s. The second one is the launch of the IOP publication on behalf of the B-MRS, Materials Science Impact, reporting advances in Materials Research in Brazil.
The Opening Ceremony will be followed by the Memorial Lecture “Joaquim Costa Ribeiro”, Progresses in Materials Research in Brazil by Professor José Arana Varela. During the Closing Ceremony the symposium coordinators will honor students with the “Bernhard Gross Award” for the best poster and the best oral presentation of each Symposium.
On behalf of Organizing Committee, we would like to thank the Brazilian Materials Research Society staff and board, the hired agencies, the symposium coordinators, the program, local and national committee members, for their commitment and great effort to make this Meeting possible.
We hope that the participants will have a very pleasant Meeting with stimulating exchange of scientific informations and establishment of new collaborations.
Ieda M. Garcia dos Santos and Severino Jackson Guedes de Lima
Prof. Chang and other developers of Nanocos, a card game that encourages students to learn science concepts and their role at the nanoscale.
Robert Chang is a Professor of Materials Science and Engineering at the first materials science academic department in the world, created more than 50 years ago at Northwestern University, where he is also director of the Materials Research Institute.
He holds a Bachelor of Science in Physics from Massachusetts Institute of Technology (MIT) and a Ph.D in Plasma Physics from Princeton University. He spent 15 years performing basic research at Bell Labs (Murray Hill). During the past 28 years at Northwestern University, he has directed several National Science Foundation (NSF) centers and programs in materials research and education.
Prof. Chang was the president of the Materials Research Society (MRS) in 1989. He is the General Secretary and Founding President of the International Union of Materials Research Societies (IUMRS). He has received many distinctions for his work, such as the Woody Award from MRS in 1987, the Siu Lien Ling Wong Fellow from the Chinese University of Hong Kong in 1999, and the NSF Director’s Distinguished Teaching Scholar Award in 2005. He is fellow of the American Vacuum Society and MRS, and honorary member of Materials Research Societies of India, Japan and Korea.
He is (co)author of 400 peer reviewed journal articles, with near 13,000 citations, and h-index of 56.
Read our interview with the plenary speaker.
SBPMat newsletter: – Under your viewpoint, which are your main contributions in the field of Materials Science and Engineering?
Robert Chang: 1. Plasma processing of semiconducting materials;
2. Carbon based materials, such as diamond, fullerene, and carbon nanotubes, and their related devices;
3. 3rd generation solar cells;
4. Infrared plasmonics and sensors;
5. Thin film oxides for electronic and photonic devices.
Top publications below.
H. Cao, Y. G. Zhao, S. T. Ho, E. W. Seelig, Q. H. Wang, and R. P. H. Chang. Random Laser Action in Semiconductor Powder. Phys. Rev. Lett. 82, 2278 (1999); DOI:http://dx.doi.org/10.1103/PhysRevLett.82.2278.
Michael D. Irwin, D. Bruce Buchholz, Alexander W. Hains, Robert P. H. Chang, and Tobin J. Marks.p-Type semiconducting nickel oxide as an efficiency-enhancing anode interfacial layer in polymer bulk-heterojunction solar cells. PNAS, vol. 105 no. 8, 2783–2787 (2008); doi: 10.1073/pnas.0711990105.
Q. H. Wang, A. A. Setlur, J. M. Lauerhaas, J. Y. Dai, E. W. Seelig and R. P. H. Chang. A nanotube-based field-emission flat panel display. Appl. Phys. Lett. 72, 2912 (1998);http://dx.doi.org/10.1063/1.121493.
Quanchang Li, Vageesh Kumar, Yan Li, Haitao Zhang, Tobin J. Marks, and Robert P. H. Chang. Fabrication of ZnO Nanorods and Nanotubes in Aqueous Solutions. Chem. Mater., 2005, 17 (5), pp 1001–1006. DOI: 10.1021/cm048144q.
SBPMat newsletter: – And what about your main contributions to science education, especially in Materials Science?
Robert Chang: – Over the past 20 years, I have led the development of the Materials World Modules program to teach pre-college students about Materials and Nanotechnology: materialsworldmodules.org; nclt.us; gsasprogram.org; imisee.net.
SBPMat newsletter: – Please give us a short teaser about your plenary talk at SBPMat meeting. What do you intend to broach?
Robert Chang: – Mobilizing world-citizens to solve global problems together!
SBPMat newsletter: – Feel free to leave other comments to our readers from the Materials research community, if you want so.
Robert Chang: – Materials and nanotechnology research and education are the driving force of all future technologies, including energy, environment, health, and security.
“Luminescence applied to nanomedicine” is the subject of one of the plenary lectures that the Materials research community is going to enjoy in our XIII SBPMat Meeting (João Pessoa, Brazil, September 28th to October the 2nd). The speaker will be the Portuguese physicist Luís António Ferreira Martins Dias Carlos, full professor at the University of Aveiro (Portugal), who got his Ph.D. in physics from the University of Évora (Portugal) in 1995 working on photoluminescence of polymer electrolytes incorporating lanthanide salts.
At the University of Aveiro, Luís Carlos created in 2000 a research group in functional organic-inorganic hybrids. The group has established an international network devoted to these luminescent hybrid materials with more than 30 research groups in Europe, China, Japan, Singapore, Brazil and Australia. Also at Aveiro, Luís Carlos has been, since 2009, the vice-director of the Centre for Research in Ceramics and Composite Materials (CICECO), one of the largest European institutes in the Materials and Nano fields.
He is member of the Lisbon Academy of Sciences (Physics section) since 2011. He was visiting professor of São Paulo State University (UNESP), Brazil, in 1999, 2012 and 2013, and of University of Montpellier 2, France, in 2008. He awarded a ‘Pesquisador Visitante Especial’ grant by the CNPq, Science Without Borders Program, Brazil in 2013.
He has co-authored more than 345 papers in international journals, 8 invited reviews, 5 book chapters, and 2 international patents. He has more than 8.050 citations, having h-index of 47. He has given 40 plenary and invited lectures at conferences. He is associate editor of the Journal of Luminescence.
Read our interview with the plenary speaker.
SBPMat newsletter: – Are there nanomedical applications to luminescent materials already on the market/spread in society? Please, give some high-impact examples.
Luís Carlos: – Undoubtedly yes, there are luminescent materials with important applications in nanomedicine already on the market. I can highlight two examples:
1. Organic complexes based on lanthanide ions (as, for example, cryptates and β-diketonates) are sold as contrast agents for magnetic resonance imaging (essentially using Gd³+) and luminescent markers (using Eu3+, Sm3+ and Tb3+) for fluoroimmunoassays. The fluoroimmunoassay is an immunological method for clinical diagnosis that is particularly relevant in prenatal and neonatal screening tests, as well as to detect proteins, viruses, antibodies, tumor biomarkers and medicine residues. In this respect, it is worth mentioning the work conducted by several researchers from the INCT INAMI (Brazilian National Institute of Science and Technology on Nanotechnology for Integrated Markers), implementing a prototype in the hospital environment in order to develop methods to diagnose the American cutaneous leishmaniasis, prostate cancer (PSA) and low density lipoprotein (LDL) by fluoroimmunoassay, using recombinant antigens marked with lanthanide ions complexes (for example, Eu3+, Tb3+ and Nd3+). The international market for contrast agents and luminescent markers based on lanthanide ions is valued in many hundreds of millions of US dollars.
2. Luminescent nanoparticles (“quantum dots”, QDs, and nanocrystals incorporating lanthanide ions) have played a major role in the last years thanks to very important applications for diagnosis by optical imaging and therapy techniques. Recent estimates value the international market for luminescent nanoparticles in the medical field in over 20 million US dollars. A notable example in the treatment of tumors is the local hyperthermia. Local hyperthermia, also referred as local thermotherapy, is a type of treatment in which biological tissues (typically cancer cells) are exposed to temperatures above 45° C, irreversibly damaging them and causing their death (the collateral damage to the healthy tissues surrounding the tumor is usually minimal). Numerous clinical trials with hyperthermia are being currently performed around the world so we can better comprehend and improve the technique. For example, the use of luminescent or magneto-luminescent particles (with magnetic ions such as Iron or Cobalt), vectored to bind to specific points in the cancer cells, enabling the local heating by the absorption of electromagnetic radiation and magnetic induction, respectively, is a new type of local hyperthermia. Precise temperature control in the irradiated area, limiting the effects of high temperature on the rest of the body, still is one of the key challenges for the popularization of the technique.
SBPMat newsletter: – Could you briefly describe the main challenges in the field of luminescence applied to nanomedicine?
Luís Carlos: – I can point out two examples: improving the imaging techniques for diagnosis and developing luminescent micro/nanothermometers which allow mapping the intracellular temperatures with a resolution of the order of tenths of a degree.
In regard to imaging applications in nanomedicine, emitting centers in the near-infrared region (for example, lanthanide ions such as Nd3+ and Yb3+, QDs and organic dyes) have great advantages over those in the visible region. For instance, biological tissues present less autofluorescence in the near-infrared window, which enables a better signal-to-noise discrimination and improves the sensibility to detection. Also, in comparison to the ones in the visible region, near-infrared photons interact less with biological tissues, which reduces the risk of disturbance or damage in the observed biological system. Thus, there is no doubt that the synthesis of new luminescent nanoparticles, emitting efficiently in near-infrared (in some cases producing persistent luminescence, i.e., light emissions that last for minutes, hours or even days, after the excitation is over), will lead us to a revolution in fluorescence microscopy, with the development of in vitro and in vivo imaging techniques in near-infrared (whose radiation penetrates deeper into the biological tissue, when compared to visible light).
The development of luminescent micro/nanothermometers to map the intracellular temperature, particularly in cancer cells, will surely improve our current perception on their pathology and physiology, optimizing early diagnosis and therapeutic processes (as seen above in the case of local hyperthermia). These non-invasive thermometers are a critical tool for better understanding a set of cellular processes followed by alterations in temperature, such as cell division, gene expression, or changes in the metabolic activity. Finally, the development of luminescent nanothermometers in the near-infrared region, which are capable of sensing heat and penetrate deeper into the biological tissue, will pave the way for in vivo thermal sensing and imaging (in small animals, in a first stage).
SBPMat newsletter: – Under your viewpoint, which are the main contributions you made to the field of Materials Science and Engineering during your scientific career? Could you please include a selection of 3 or 4 of the most important publications among your work in your answer?
Luís Carlos: – Normally, our latest works tend to seem to be the most important… Regardless, I understand that my main contributions to Materials Science and Engineering are related to the development of i) luminescent organic-inorganic hybrid materials, ii) ratiometric nanothermometers based on the characteristic emission of lanthanide ion pairs (Eu3+/Tb3+ and Er3+/Yb3+) and iii) nanoplatforms combining nanoheaters (metal particles of Gold or Silver) and nanothermometers which allow to increase the local temperature by laser irradiation while simultaneously mapping such temperature increase with precision. The following four papers illustrate these contributions:
Full Colour Phosphors From Eu(III)-Based Organosilicates. L. D. Carlos, Y. Messaddeq, H. F. Brito, R. A. Sá Ferreira, V. de Zea Bermudez, S. J. L. Ribeiro, Adv. Mater. 12, 594–598 (2000)
Nanoscopic Photoluminescence Memory as a Fingerprint of Complexity in Self-Assembled Alkylene/Siloxane Hybrids. L. D. Carlos, V. de Zea Bermudez, V. S. Amaral, S. C. Nunes, N. J. O. Silva, R. A. Sá Ferreira, J. Rocha, C. V. Santilli, D. Ostrovskii, Adv. Mater. 19 341–348 (2007)
A Luminescent Molecular Thermometer for Long-Term Absolute Temperature Measurements at the Nanoscale. C. D. S. Brites, P. P. Lima, N. J. O. Silva, A. Millán, V. S. Amaral, F. Palacio, L. D. Carlos, Adv. Mater. 22, 4499–4504 (2010)
All-In-One Optical Heater-Thermometer Nanoplatform Operative From 300 to 2000 K Based on Er3+ Emission and Blackbody Radiation. M. L. Debasu, D. Ananias, I. Pastoriza-Santos, L. M. Liz-Marzan, J. Rocha, L. D. Carlos, Adv. Mater. 25, 4868–4874 (2013)
The German physicst Karl Leo studied physics at the Albert Ludwigs University of Freiburg (Gemany) and obtained the “Diplomphysiker” degree with a thesis on solar cells at the Fraunhofer Institute for Solar Energy Systems (Germany). In 1988, he obtained the PhD degree from the University of Stuttgart for a doctoral thesis performed at the Max Planck Institute for Solid State Research in Stuttgart. From 1989 to 1991, he was a postdoc at AT&T Bell Laboratories (United States). In 1991 he joined the RWTH Aachen University (Germany) as an assistant professor and obtained the Habilitation degree. In 1993 he joined the Dresden University of Technology (Germany) as a professor of optoelectronics. Since 2001 until 2013, he has been also with the Fraunhofer Institute for Photonic Microsystems, being head of department and then director.
He won some of the most prestigious German awards in science, technology and innovation, such as the Leibniz award (2002) and the German Future Prize (2011).
He is the author of more than 550 refereed publications, with more than 23.000 citations, having an H index = 73 (Google Scholar). He is (co-)inventor of approximately 50 patent families.
Since 1999 he has co-founded 8 spin-off companies, such as Heliatek and Novaled, which have employed more than 250 people and raised more than 60M€.
Prof. Karl Leo with an organic solar cell module on test on the roof of Kaust university, in Saudi Arabia.
Read our interview with the lecturer.
SBPMat newsletter: – Under your viewpoint, which are your main contributions in the field of Materials Science and Engineering? Please think about papers, patents, spin-off companies, products etc.
Karl Leo: – I spent most of the last decades improving organic semiconductors and developing new device concepts for organic semiconductor devices. One example is the development of controlled electrical doping, which allowed much higher electrical conductivities. As a result, we could e.g. realize white organic light emitting diodes which are more efficient than fluorescent tubes. As device principle, we e.g. developed novel vertical transistors which can drive very high currents so that they can be used to drive OLED displays.
SBPMat newsletter: – Please give us a short teaser about your plenary talk at the XIII SBPMat meeting. What do you intend to broach?
Karl Leo: – I will talk about highly efficient organic devices, touching both organic LED and organic solar cells. I will describe the challenges in materials research and the importance of new device concepts.
SBPMat newsletter: – Could you choose some of your main publications (about 3 or 4) on the topics of your plenary lecture to share them with our public?
Karl Leo: –
1. Doped Organic Transistors: Inversion and Depletion Regime. Lüssem, B., Tietze, M.L., Kleemann, H., Hoßbach, C., Bartha, J.W., Zakhidov, A. and Leo, K. , Nature Comm. 4, 2775 (2013).
2. Phase-locked coherent modes in a patterned metal-organic microcavity. Brückner, R. Zakhidov, A., Scholz, R., Sudzius, S., Hintschich, S.I., Fröb, H., Lyssenko, V.G. and Leo, K., Nature Photonics 6, 322–326 (2012).
3. White organic light-emitting diodes with fluorescent tube efficiency. Reineke, S.; Lindner, F.; Schwartz, G. et al., Nature 459, 234 (2009).
SBPMat newsletter: – Feel free to leave other comments to our readers from the Materials research community.
Karl Leo: – The field of materials research is as exciting as ever, and in the field of organic semiconductors, we are still in the beginning, maybe where silicon was in 1970…
The Italian chemist Roberto Dovesi, full professor at Universita´degli Studi di Torino, where he heads the Theorical Chemistry Group, will be one of the plenary speakers in our XIII SBPMat Meeting. Dovesi will talk about theoretical calculations applied to materials.
His scientific activity focuses on the use of a quantum-mechanical approach to solid state chemistry, physics, materials science and surface science. In particular, his primary activityis the implementation of ab initio computer programs for the study of the electronic structure of periodic compounds.
Dovesi is one of the creators of CRYSTAL, a computational tool for the characterization of crystalline solids.The CRYSTAL project started in 1976, and involved (and still involves) a large number of collaborators from many countries. The first version of the software was released in 1988, and then new versions have followed. CRYSTAL is today a licenced program used in more than 350 laboratories in the world. In the last five years, more than 30 PhD students and post-docs from European countries visited the Torino Theoretical Chemistry Group in order to be introduced to the formal aspects and use of the CRYSTAL code.
Every year Dovesi’s group organizes international schools on the quantum-mechanical simulation of solids. One of them was held in 2012 in Brasil. This year four such schools are organized in Perth (Australia), Jahnsi (India), Regensburg (Germany), London (UK) (see at the EVENTS entry in the CRYSTAL web site) .
Roberto Dovesi is the author of more than 250 papers published in international journals and of one book (with Cesare Pisani and Carla Roetti) published by Springer in 1989. Since 1985, he received more than 7.000 citations with h-index=51.
Read our interview with the lecturer.
SBPMat newsletter: – Share with us, very briefly, the story of the developement of CRYSTAL since the first idea up to commercialization.
Roberto Dovesi: – In 1970 Cesare Pisani, Carla Roetti and myself decided to explore the possibilities of simulation as a complement to experiment in the study of crystalline solids.
We started to develop small codes on the basis of the analogy with the codes that were appearing in the litterature as produced mainly by USA universities. In 1976 we started to implement an ab initio quantum mechanical code for solids, using tools and methodologies that were common to the Theoretical Chemistry community (as opposed to the Solid State community). It took 4 years of very hard study and coding to have a first, preliminary result, the band structure of graphite, and its total energy. Eight years later, in 1988, CRYSTAL was ripe enough to be publicly distributed by QCPE (Quantum Chemistry Program Exchange). CRYSTAL has been the first periodic code distributed publicly to the scientific community.
In the meantime many new collaborators where joining the group from many countries (I want to mention at least one of them, Vic Saunders, fron the Daresbury Laboratory, U.K). In the following years many new public releases have been distributed (1992, 95, 98, 2003, 2006, 2009, 2014), each one corresponding to generalizations and extensions of the code in many directions. The last release (CRY14) has been distributed in more than 200 laboratories in less than one year.
The Raman spectrum of Pyrope.
SBPMat newsletter: – Please explain to our broad audience what can be done with CRYSTAL in the field of Materials Science and Engineering.
Roberto Dovesi:- CRYSTAL can be used for studying many ground state properties of systems periodic in 1 (nanotubes, polymers), 2 (monolayers, slabs) and 3 (crystals) dimensions; solid solutions, molecules and clusters can be investigated too. Hartree-Fock and DFT of various flavours are the available hamiltonians. A very large set of properties can be studied, the list can be found at www.crystal.unito.it. A short list includes the elastic, piezo-electric, photo-elastic, dielectric, polarizability and hyperpolarizability tensors, the IR and RAMAN spectra, the electron and phonon band structure.
SBPMat newsletter: – Please choose some of your main publications (about 3 or 4) to share them with our public.
Roberto Dovesi: –
1. Raman Spectrum of Pyrope Garnet.A Quantum Mechanical Simulation of Frequencies, Intensities, and Isotope Shifts. Lorenzo Maschio, Bernard Kirtman, Simone Salustro, Claudio M. Zicovich-Wilson, Roberto Orlando and Roberto Dovesi. J. Phys. Chem. A, 2013, 117 (45), pp 11464–11471.
2. Structural, electronic and energetic properties of giant icosahedral fullerenes up to C6000: insights from an ab initiohybrid DFT study. Yves Noel, Marco De La Pierre, Claudio Marcelo Zicovich Wilson, Roberto Orlando, Roberto Dovesi. Phys Chem Chem Phys. 2014, Jun 11; 16(26):13390-401.
3. Symmetry and random sampling of symmetry independent configurations for the simulation of disordered solids. Philippe D’Arco, Sami Mustapha, Matteo Ferrabone, Yves Noël, Marco De La Pierre, Roberto Dovesi. J Phys Condens Matter. 2013 Sep 4; 25(35): 355401.
SBPMat newsletter: – Tell us what do you intend to broach in your plenary talk at SBPMat meeting.
Roberto Dovesi: – I will try to show that nowadays quantum mechanical simulation can be an useful complementary tool to experiment. The decreasing cost of the harware, and the availability of powerful, accurate and general computer codes permits to perform simulations also to non experts. I will show that the number of available properties makes simulation very interesting.
“Organic electronic devices” is the subject of the plenary talk that will be given by Professor Alberto Salleo at the XIII SBPMat Meeting. Professor Salleo is the head of a research group at Stanford University (USA), working on novel materials and processing techniques for large-area and flexible electronic/photonic devices. Salleo received his Laurea degree in Chemistry in 1994 from the University of Rome La Sapienza (Italy) and his M.S. (1998) and Ph.D. (2001) in Materials Science from UC Berkeley (USA) investigating optical breakdown in fused silica. He spent 4 years at the Palo Alto Research Center (USA) before joining the Department of Materials Science and Engineering at Stanford University in December 2005. Salleo is Principal Editor of MRS Communications, Associate Editor of the Journal of Electronic Materials, and member of the Advisory Board of the Journal of Organic Electronics. Salleo was awarded the Early Career Achievement Award from SPIE, the International Society for Optics and Photonics and the 3M Untenured Faculty Award, among other honors. He has (co)/authored over 140 papers in peer-reviewed journals and 6 book chapters and has co-authored a book on flexible electronics.
Read our interview with the lecturer.
SBPMat newsletter: – Please choose some of your main publications on organic electronics to share them with our public.
Alberto Salleo: – My group has long been interested in the role defects play in transport in organic semiconductors. We combine materials characterization to correlate structure to properties and really get deep in the “Materials Science” of organic semiconductors. In 2009 we looked at the role of grain-boundary structure in charge transport in crystalline organic semiconductors [J. Rivnay, L. Jimison, J. Northrup, M. Toney, R. Noriega, T. Marks, A. Facchetti, A. Salleo, “Large Modulation of Carrier Transport by Grain Boundary Molecular Packing and Microstructure in Organic Semiconductor Thin Films. Implications for Organic Transistor Performance”, Nature Materials 8, 952-958 (2009)]. Later, we extended this work to understanding how the microstructure of semicrystalline polymers affects carrier mobility and we outlined some basic design rules for materials [R. Noriega, J. Rivnay, K. Vandewal, F.P.V. Koch, N. Stingelin, P. Smith, M.F. Toney, A. Salleo, “A general relationship between disorder, aggregation and charge transport in conjugated polymers”, Nature Materials, 12, 1037-1043 (2013)].
In the last few years we have been interested in the fundamental processes of charge generation in organic photovoltaics. In collaboration with other groups we discovered the fundamental intermediate of the charge generation process, which is the thermalized charge-transfer state [K. Vandewal, S. Albrecht, E.T. Hoke, K.R. Graham, J. Widmer, J.D. Douglas, M. Schubert, W.R. Mateker, J.T. Bloking, G.F. Burkhard, A. Sellinger, J.M.J. Frechet, A. Amassian, M.K. Riede, M.D. McGehee, D. Neher, A. Salleo, “Efficient charge generation by relaxed charge-transfer states at organic interfaces,” Nature Materials 13, 63-68 (2014)].
Charge transport in heterogeneous polymeric microstructures is dominated by percolation through ordered regions.
SBPMat newsletter: – In your opinion, which are the organic electronics´main challenges for Materials Science and Engineering? And the main applications of organic semiconductors we´ll see in everyday life in the next decades?
Alberto Salleo: – Because these materials are bound by weak van der Waals bonds, their microstructure is very process-dependent. This is a great property for fundamental studies as it allows to generate a zoo of structures relatively easily. On the other hand, most applications require that many (sometimes thousands) of devices be integrated, which puts stringent requirements on the reproducibility of the electrical characteristics. Reaching the level of reproducibility needed to build somewhat complex circuits is still challenging.
As far as applications, it is important to think of a space that is well-matched to the unique properties of organic semiconductors. OLED displays are already commercial but maybe in the future they can be driven by organic transistors to further push flexibility and fabrication sustainability. OLEDs are also exciting as low-power, low-cost lighting sources. Of course, there is continuing progress in photovoltaics and the possibility of organics being part of tandem cells is becoming ever more realistic, while fundamental breakthroughs may also make them competitive as single junctions in specific applications where their low weight and flexibility add value. Finally, there are plenty of applications that don’t require great speed but that take advantage of the mechanical properties of organics. I am thinking of bio-electronics and wearable electronics, which are experiencing a significant growth lately. Organic devices have been used to monitor brain signals and to deliver drugs locally, as well as to measure heartbeat or oxygen content in blood.
SBPMat newsletter: – Tell us a little about the plenary lecture on organic electronic devices you are going to give at the XIII SBPMat Meeting.
Alberto Salleo – My interest is in understanding how microstructure and defects play a role in materials properties. In the end, these relationships are important for all devices, therefore I view our work as quite fundamental, regardless of applications. My goal for the lecture is to pick a device (I have a few months to decide which one!) and show exactly how the structure of the material at all length-scales affects the device behavior. This type of studies provides a nexus between scientists who make materials, those who process materials and those who design devices.
