Technology Spain , Madrid, Tuesday, July 28 of 2015, 17:58

“Organic semi-conductors are inexpensive, flexible, transparent, lightweight, allowing for new electronic devices”

Interview with Lucas Viani, UC3M CONEX researcher

UC3M/DICYT Lucas Viani (Ribeirão Preto, Brazil; 1983) carries out research on organic semi-conductors in the Instituto Universitario sobre Modelización y Simulación en Fluidodinámica, Nanociencia y Matemática Industrial "Gregorio Millán Barbany" within the framework of the CONEX program (CONnecting EXcellence) at Universidad Carlos III de Madrid (UC3M). This talent attraction program is supported by the European Union (Marie Curie actions of the 7th Framework Program), the Ministry of Economy and Competitiveness and the Banco Santander.

How much physics and how much chemistry is there in your research?

Material science is an interdisciplinary field where physicists, chemists, and engineers work together, providing different insight into a problem seeking the common goal of developing and/or improving the materials currently existent. The main objective of material science is to fulfill the needs of the contemporary society through innovation. Some issues addressed today are the reduction of energy consumption in devices, boosting the energy storage capabilities of batteries, development of systems delivering green energy solutions, thus capable of capturing the energy available in the sun light, wind, and earth (geothermal).

What applications do organic semi-conductors have?

Organic semi-conductors are capable of providing solutions to different problems faced today, through the intelligent use of their intrinsic properties (inexpensive, flexible, transparent, lightweight), allowing for new concepts and designs of electronic devices. The best example is organic light-emitting diodes (OLEDs). It was the first organic based device to be produced in large scale, and has revolutionized the display industry by providing a hardware consuming much less energy, rendering better output quality, and using less physical space. They are found today in mobile phones and ultra-thin and high resolution TVs, allowing for unique solutions such as curved TVs and transparent displays.

Where are we going in this field?

A group of devices, including the organic photovoltaics (OPVs), field-effect transistors (OFETs) and lasers (OSLs), are promising candidates to follow the same path as OLEDs and dominate part of the market in their own segments, although, low efficiencies are still the main reason holding back large scale commercialization.

To what point could the efficiency of OPVs or OLED technology be increased?

Today the OLED industry is at an advanced level and highly efficient devices can be found in the market. The challenges found today are in the fine tuning of the display's properties and in the development of devices for indoor lighting and architectural purposes. OPV has reached now a level in which it can compete in some areas with different photo-voltaic technologies, although its global efficiency has to be improved (current efficiency record is ~12% and it is theoretically possible to reach up to 20-24%).

What is the aim of your research at UC3M?

The project I am developing here aims to provide a detailed understanding of exciton dynamics in conjugated organic materials via computational methods with the objective of improving the efficiency of organic based electronic devices, so they can be brought to commercialization.

How are you planning to do this?

It will be done by implementing a theoretical tool capable of describing in a more realistic way the charge and energy transport dynamics among organic molecules, in order to validate and assess information currently not accessible to experiment techniques. It will provide unique insights on the parameters governing such mechanisms, thus saving time and money on the synthesis of new compounds, by testing its characterized energy (ET) and charge transfer (CT) properties prior synthesis, at the same time, it will allow new device designs in organic-electronics by helping in the description and tuning of their relevant properties.

What methodology do you use in your research?

The methodologies commonly adopted to describe long time scale ET dynamics for systems in which the analytical solution is not possible, are based on stochastic methods solving the Pauli master equations or relies on a static approach based on the extraction of the molecular conformations from classical molecular dynamics simulations used in the prediction of the CT and ET dynamics using kinetic Monte-Carlo schemes over a frozen snapshot. In this project we will integrate the different steps into one, in order to reduce/avoid losses of structural and electronic information essential to obtain a detailed prediction of the dynamic properties.

What’s the most complicated thing when doing this research?

I would say that all steps in a research projects are important, from the first steps, when the project is conceived, until its implementation and validation steps. In all phases of a project there are decisions and approximations to be made and in most cases they must be done without a prior knowledge of the outcome. I would say that the most important stage of this project will be the validation of the methodology, which will allow us to direct the development of the project in specific directions, and eventually translate this methodology to different kinds of systems.

Do you use computational methods? Is this related to the software MView that you created?

MView is software I've been developing in the past years with the goal to centralize and generalize the computational methods. Its main purpose today is to provide tools to assist in the analysis and visualization (through an OpenGL interface) of molecular properties and dynamics. The resulting theoretical tools of the CONEX program will also make part of it, which translates into a more user friendly interface, facilitating the use by other researchers.

What does researching at the UC3M within the CONEX program bring to your work?

I find the CONEX program to be a great opportunity to focus on my research lines, allowing me to develop independent research and develop theoretical tools to be used in the investigation of dynamic processes taking place among organic semiconductors. The UC3M has proven to be a proper environment, providing the financial, technological, and personal support needed for a successful program.

Where were you working before coming to the UC3M with the CONEX program?

Before coming to UC3M I have worked in different centers of excellence in Europe, the United States, and Brazil. I graduated in physics at the University of Campinas, and finished my master at the University of São Paulo, Brazil. In 2007, I started to work on my PhD thesis at the University of Mons, Belgium, supervised by Dr. Jérôme Cornil, where I studied and characterized energy (ET) and charge (CT) transfer in supramolecular host-guest systems using computational tools based on quantum mechanics, with the final goal of developing new designs for organic devices. Upon completion of my PhD I joined the research group of Dr. Jean-Luc Brédas at Georgia Institute of Technology, where I focused my research on the understanding of CT processes in typical organic-inorganic interfaces found in organic filed-effect transistors (OFETs). In 2012 I joined Dr. Benedetta Mennucci at the University of Pisa, where I applied my previous knowledge on the investigation of ET properties in biological light-harvesting complexes, contributing to the understanding of the photosynthesis process in plants and bacteria.