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Organic electronics

Flexible illumination

New kinds of organic lamps and photovoltaic cells are being developed at a research center in the State of Minas Gerais

Zé Takanashi - Agencia Fotosite / CSEMFashion designer Ronaldo Fraga’s runway show during this year’s São Paulo Fashion Week: models with ribbon lampsZé Takanashi - Agencia Fotosite / CSEM

Flexible lamps in the shape of ribbons that can be attached to walls, ceilings and even to baseboards. Lighting architecture and technology are going in this direction and new ways of using these flexible ribbons, made mostly of polymers, have enabled unusual uses even before becoming commercial. This was illustrated by fashion designer Ronaldo Fraga’s runway show during the São Paulo Fashion Week, held in São Paulo in June of this year. The models were embellished with electroluminescent ribbons called Lume. The ribbon lamps are manufactured by Csem Brasil, a private applied research center in the State of Minas Gerais. The Center specializes in technology development and transfer, especially in the field of organic electronics and micro systems. Connected to tiny batteries attached to the models’ bodies, the ribbon lamps were publicly displayed for the first time.

The development and manufacturing of the Lume in Brazil has placed the country on a par with Europe, the United States, and China in this respect, within a global market that still has plenty of room to be explored. The Lume ribbons generate light over an entire surface and are mostly used in the production of displays for electronic products, such as clocks, the interior of airplanes and automobiles, advertising panels and decorative elements. They last for about 10 thousand hours and are energy-efficient.

Csem resorted to the electronic roll-printing technology used to make organic semiconductors, even though these illuminated ribbons do not specifically use organic polymers. The Lumes are manufactured in a printing machine called Roll to Roll, the first of its kind in South America. It works like a newspaper rotary press. Basically, the Lume contains a layer of a phosphorus-based material between two electrodes. One electrode, called ITO – the acronym for indium tin oxide, is transparent. The other one is a silver ink electrode. The electric field formed by the two electrodes lights up the phosphorus electrons and when they return to their original state they emit a red, white, blue, or green light, depending on the color of the paint that was used. The flexible lamp uses a PET polymer as a substrate, the same one used for soft drink and mineral water bottles. The ribbon is formed by going through the machine’s rolls and receives different layers.

The organic polymers are the main elements in the manufacturing of organic light-emitting diodes (Oleds), composed mostly of carbon. Oleds are the next big thing in the lighting and screen industry after the LED, used in special lamps and TV screens. The technological route for the manufacturing of the Lume is the same followed by the Oleds and opens up the way for the development of devices with organic polymers, such as photovoltaic cells that can be printed and flexible, used in solar energy generation systems. Csem does not plan to invest in the large-scale production of Oleds or displays at present. Other countries are ready to dominate the manufacturing of these devices. This is why engineer Tiago Maranhão Alves, executive director of the Center, states that the photovoltaic cell made of organic semiconductors will be the first organic product manufactured for general consumption.

The roll machine that prints and produces the ribbons

Fernando Lutterbach / CSEMThe roll machine that prints and produces the ribbonsFernando Lutterbach / CSEM

Recycling energy
“Besides being able to gain significant market share, we have the natural resources to enter, compete and win this game,” he says. According to Venter’s plan, the first commercial photovoltaic cells will be on the market within a year. They can be used to make low-cost, light and flexible solar panels, computer keyboard drivers, mobile devices, and remote controls. These cells will also be able to capture home light or sunlight and produce an electric current, acting as an “energy recycler.” Another market for these cells will be the electric power generation in remote locations that lack power distribution grids.

In Maranhao’s opinion, nobody can build a new value chain alone. “This can only be done through extensive research and partnerships.” Csem has already got funding from the State of Minas Gerais (Foundation for the Support of Research/Fapemig) and from the National Bank for Social and Economic Development (BNDES) for its projects. In Minas Gerais, an agreement between the State Bureau of Science and Technology, Fapemig and the private sector is driving the development of that technology. “The important feature of this project is that the government is fostering a partnership between the university and the private sector to develop state-of-the-art technology that will generate wealth, jobs and development for the country,” explains Mario Neto Borges, Fapemig chairman. The foundation has already invested R$ 7 million and the Center and the BNDES added another R$ 15 million.

Joint exchange
A Memorandum of Understanding for Academic Cooperation, Research, and Development signed by the institutions has led to an exchange program involving researchers and professionals with master’s degrees, doctorates, and post-doctorates. The professionals come from universities and companies in the State of Minas Gerais. The Imperial College Center for Plastic Electronics has also partnered with the Minas Gerais Center. The latter is one of the world’s foremost organic electronics centers. Physicist Donald Bradley, the Center’s director, is one of the inventors of electroluminescence in conjugated polymers. Ten Brazilian researchers have already worked with him thanks to an exchange agreement. Upon their return, they were hired by Csem. Pursuant to the agreement, the patents registered by the center will belong to the partners involved in the project, including Fapemig.

075-077_Lampadasnafita_199The first steps that resulted in organic and print electronics were taken in Tokyo in 1976. That year, Hideki Shirakawa, a Japanese researcher from the Tokyo Technological Institute, was trying to synthesize polyacetylene, a type of plastic. Polyacetylene is a simple polymer made up of two atoms: carbon and hydrogen. But the researcher made a mistake – he added more catalyst than necessary to the compound. By doing this, Hideki produced a shiny film that resembled aluminum foil. Soon thereafter, he partnered with two American scientists – chemist Alan MacDiarmid and physicist Alan Heeger, who were working at the University of Pennsylvania. While working on the shiny film that had been produced by the Japanese researcher, the two Americans noticed that when doping carbon with iodine, the film turned into a golden metallic sheet with electric conductivity. This was how the first organic semiconductor made from a polymer was discovered. The discovery resulted in the Nobel Prize for Chemistry, awarded to the three scientists in 2000. Nearly 40 years after this discovery, many practical applications for those semiconductors have been analyzed. Now the race is on among scientists, private institutions and government institutions to discover how to manufacture these organic and print electronics-based products efficiently, inexpensively and on a wide scale.

The race to place the Oled in the market has driven major lighting manufacturers, such as Germany’s Osram, to invest in Oleds made with organic semiconductors. The main advantage of this material is that it is not a junction of individual emitting points. It consists of a flexible surface that generates light uniformly and which can therefore be more easily molded and adapted to different shapes and environments. The company has a manufacturing facility in the city of Regensburg, Germany, prepared to be the first large-scale, Oled pilot production line in the world. The first commercial products used to light offices and in the retail industry have already been tested in Munich and Berlin and are scheduled to come to Brazil in the near future. Joyce Calil, Osram’s sales manager in Brazil, expects that “from 2015 onwards, the first applications in the market will be for functional light.”