15/01/2015

Suchi Guha reúne físicos e químicos por eletrônicos flexíveis eficientes

Especialista em eletrônicos orgânicos será palestrante na 38ª. RASBQ

"In the 21st century, science has a large role to play not just for improved technology but for a better sustainable living. Be it preserving our natural resources, improving human health, or building spaceships, the future of nations depends upon investing in science."

Imagine que você possa enrolar a tela de sua televisão como se fosse uma cortina ou ter seu computador construído na própria roupa que você usa. Isso pode parecer ficção, como diz a Profa. Suchi Guha, da Universidade do Missouri, que participará da 38ª. Reunião Anual da SBQ. Mas eletrônicos "orgânicos" ou "plásticos" estabelecem um caminho para dispositivos flexíveis, que serão uma realidade no futuro próximo. "A eletrônica convencional é baseada em materiais como silício e outros condutores inorgânicos que por serem duros e frágeis não apresentam a flexibilidade dos "eletrônicos orgânicos". Já a eletrônica orgânica é fundamentada em semicondutores poliméricos solúveis, uma opção de baixo-custo para circuitos eletrônicos, que podem facilmente ser feitos em papel, tecido ou outros "substratos flexíveis", explicou a Profa. Suchi ao Boletim da SBQ.

Ela é professora da Faculdade de Física e Astronomia da Universidade do Missouri, nos EUA, onde lidera um grupo de pesquisa em semicondutores orgânicos. Seu trabalho junta físicos, químicos e engenheiros que buscam tornar mais eficiente a atividade destes semicondutores, que embora "de baixo custo e flexíveis, ainda são lentos e desorganizados".

Suchi formou-se e obteve o mestrado em física em Nova Delhi, depois mudou-se para o Arizona, onde concluiu o doutorado. É coautora de mais de 90 artigos extensamente citados e tem proferido palestras em diversos países.

HOMO/LUMO of Au-pentacene complexes using DFT calculations show a charge transfer. The SERS phenomenon can be used to probe the metal/ pentacene interface in OFETs. Low-operating voltage OFETS are robust against bias stress; concomitantly the SERS maps show no change.

Ela conversou com o Boletim da SBQ:

In a broad sense, what are the basic objectives of your researches?
Our research is at the interface of physics, chemistry, materials science, and engineering, focusing on organic electronics. In particular, our emphasis is on molecular and polymer-based electronics: field-effect transistors, solar cells, photodiodes, and biomimetic devices. On the one hand, we try to answer fundamental questions on the mechanism of charge transport in organic transistors by using polymer dielectrics (including ferroelectrics), combining optical spectroscopic methods and electrical techniques. On the other hand, we are devising new methods to improve the performance of organic transistors and solar cells by controlling polymer-dielectric interfaces and incorporating new growth techniques for the polymer layer. A recent focus of our work is on peptide-based electronics, where peptide nanostructures are being used as building blocks in active electronics. This project is being developed in collaboration with Prof. Wendel Alves (UFABC).

What are your challenges concerning OFETs?
Transistors are ubiquitous in electronic circuits. However, most electronic devices around us have silicon based transistors. Organic field-effect transistors (OFETs) can be made from solution processable polymeric (semiconducting) ink. Television screens based on organic semiconducting pixels are already on the market. For displays, the pixels need to be switched on and off, which may be achieved by a back panel of OFETs. Other applications of OFETs are in different types of chemical and biological sensors, and memory devices. However, since polymeric/molecular semiconductors have more defects and are more disorganized in their structure compared to silicon, OFETs are prone to degradation. Hence, there is a need for improving their performance.

How far or close are your findings in the laboratory from the industry and, thus, the market?
Our research has both a fundamental and an applied science flavor. We have developed some unique optical tools to study the polymer-metal interfaces in OFETs that provide a powerful visualization for correlating the device performance under bias stress to the structural changes of the molecule/polymer. These methodologies may be used as a general diagnostic tool in OFETs and other organic devices.
Our strategies for developing low-operating OFETs, which consume less power compared to high-operating OFETs, using polymer dielectrics coupled with polar solvents used for dissolving the dielectric layer is a significant step towards the realization of stable low-cost OFETs. We are now in the process of developing fully printable circuits, which we believe should have commercialization benefits.

How did your passion for science start?
The fascination for science at an early stage for me was natural curiosity. The fact that various physical phenomena could be demonstrated by simple experiments was very appealing. I always wanted to be an experimentalist. A turning point as to why I studied physics may have been when we were taught the workings of a diode in middle school and yes, we were taught the workings of old fashioned vacuum diodes! It was like a "click" – I could finally understand how the old radio at home worked. To this day, I love the fact that science can be taught so effectively by using simple experimental demonstrations.

Why should young people aim for scientific careers?
In the 21st century, science has a large role to play not just for improved technology but for a better sustainable living. Be it preserving our natural resources, improving human health, or building spaceships, the future of nations depends upon investing in science. The interdisciplinary nature of physics, chemistry, biology, materials science, and engineering offers umpteen career options for the next generation of scientists.

A message for the chemical community in Brazil…
I have been visiting Brazil for the past few years, and the country's rich natural resources and its culture are striking. The educational system in Brazil provides a perfect platform for carrying out interdisciplinary science. The chemical community in Brazil could set an example of how effectively it integrates diverse areas, not just in chemistry but also other scientific disciplines.

Artigos sugeridos para conhecer o trabalho da Profa. Guha:

“Bio-inspired peptide nanostructures for organic field-effect transistors”, T. Cipriano, G. Knotts, A. Laudari, R. Bianchi, W. A. Alves, S. Guha, ACS Appl. Mater. Interfaces 2014, 6, 21408.

“Surface-enhanced Raman spectroscopic studies of metal-semiconductor interfaces in organic field-effect transistors”, D. Adil, S. Guha, J. Phys. Chem. C 2012 116, 12779.

“Low-operating voltage and stable organic field-effect transistors with poly (methyl methacrylate) gate dielectric solution deposited from a high dipole moment”, N. B. Ukah, J. Granstrom, R. R. Sanganna Gari, G. M. King, S. Guha, Appl. Phys. Lett. 2011, 99, 243302.

“Chain morphologies in semi-crystalline polyfluorene: evidence from Raman scattering”, M. Arif, C. Volz, S. Guha, Phys. Rev. Lett. 2006, 96, 25503.

“Electronic structures and spectral properties of endohedral fullerenes”, S. Guha, K. Nakamoto, Coord. Chem. Rev. 2005, 249, 1111.

Para saber mais sobre a Profa. Suchi Guha
http://web.missouri.edu/~guhas/suchi_guha.htm

A 38ª Reunião Anual da SBQ será no Hotel Monte Real, Águas de Lindóia, SP de segunda, 25/maio/2015 a quinta, 28/maio/2015. Para detalhes do evento, visite: http://www.sbq.org.br/38ra/

Curta a página da 38ª RA e acompanhe as novidades do evento! Convide também seus amigos. Juntos, faremos uma grande reunião anual!

Texto: Mario Henrique Viana (Assessoria de Imprensa da SBQ)