(Press-News.org) This news release is available in German.
They are thin, light-weight, flexible and can be produced cost- and energy-efficiently: printed microelectronic components made of synthetics. Flexible displays and touch screens, glowing films, RFID tags and solar cells represent a future market. In the context of an international cooperation project, physicists at the Technische Universität München (TUM) have now observed the creation of razor thin polymer electrodes during the printing process and successfully improved the electrical properties of the printed films.
Solar cells out of a printer? This seemed unthinkable only a few years ago. There were hardly any alternatives to classical silicon technology available. In the mean time touch screens, sensors and solar cells can be made of conducting polymers. Flexible monitors and glowing wall paper made of organic light emitting diodes, so-called OLEDs, are in rapid development. The "organic electronics" are hailed as a promising future market.
However, the technology also has its pitfalls: To manufacture the components on an industrial scale, semiconducting or insulating layers - each a thousand times thinner than a human hair - must be printed onto a carrier film in a predefined order. "This is a highly complex process, whose details need to be fully understood to allow custom-tailored applications," explains Professor Peter Müller-Buschbaum of the Chair of Functional Materials at TU München.
A further challenge is the contacting between flexible, conducting layers. Hitherto electronic contacts made of crystalline indium tin oxide were frequently used. However, this construction has numerous drawbacks: The oxide is more brittle than the polymer layers over them, which limits the flexibility of the cells. Furthermore, the manufacturing process also consumes much energy. Finally, indium is a rare element that exists only in very limited quantities.
Polymers in X-ray light
A few months ago, researchers from the Lawrence Berkeley National Laboratory in California for the first time succeeded in observing the cross-linking of polymer molecules in the active layer of an organic solar cell during the printing process. In collaboration with their colleagues in California, Müller-Buschbaum's team took advantage of this technology to improve the characteristics of the polymer electronic elements.
The researchers used X-ray radiation generated in the Berkley synchrotron for their investigations. The X-rays are directed to the freshly printed synthetic layer and scattered. The arrangement and orientation of the molecules during the curing process of the printed films can be determined from changes in the scattering pattern.
"Thanks to the very intensive X-ray radiation we can achieve a very high time resolution," says Claudia M. Palumbiny. In Berkeley the physicist from the TUM investigated the "blocking layer" that sorts and selectively transports the charge carriers in the organic electronic components. The TUM research team is now, together with its US colleagues, publishing the results in the trade journal Advanced Materials.
Custom properties
"In our work, we showed for the first time ever that even small changes in the physico-chemical process conditions have a significant influence on the build-up and properties of the layer," says Claudia M. Palumbiny. "Adding solvents with a high boiling point, for example, improves segregation in synthetics components. This improves the crystallization in conducting molecules. The distance between the molecules shrinks and the conductivity increases.
In this manner stability and conductivity can be improved to such an extent that the material can be deployed not only as a blocking layer, but even as a transparent, electrical contact. This can be used to replace the brittle indium tin oxide layers. "At the end of the day, this means that all layers could be produced using the same process," explains Palumbiny. "That would be a great advantage for manufacturers."
To make all of this possible one day, TUM researchers want to continue investigating and optimizing the electrode material further and make their know-how available to industry. "We have now formed the basis for pushing ahead materials development with future investigations so that these can be taken over by industrial enterprises," explains Prof. Müller-Buschbaum.
INFORMATION:
The research was supported by the GreenTech Initiative "Interface Science for Photovoltaics" (ISPV) of the EuroTech Universities together with the International Graduate School of Science and Engineering (IGSSE) at TUM and by the Cluster of Excellence "Nanosystems Initiative Munich" (NIM). Further support came from the Elite Network of Bavaria's International Doctorate Program "NanoBioTechnology" (IDK-NBT) and the Center for NanoScience (CeNS) and from "Polymer-Based Materials for Harvesting Solar Energy" (PHaSE), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Basic Energy Sciences. Portions of the research were carried out at the Advanced Light Source which receives support by the Office of Basic Energy Sciences of the U.S. Department of Energy.
Publication:
The Crystallization of PEDOT:PSS Polymeric Electrodes Probed In Situ during Printing
Claudia M. Palumbiny, Feng Liu, Thomas P. Russell, Alexander Hexemer, Cheng Wang, and Peter Müller-Buschbaum
Advanced Materials, June 10, 2015, 27, 22, 3391-3397 - DOI: 10.1002/adma.201500315
This news release is available in French. A multidisciplinary group of researchers from British Columbia has developed a participatory action research program to help address healthy body weight in children.
The SCOPE (Sustainable Childhood Obesity Prevention through Community Engagement) program has a simple message and was developed to engage communities to take action to prevent childhood obesity. The first phase of the SCOPE program was funded by Child Health BC, an initiative of BC Children's Hospital, and was carried out in communities in British Columbia. The ...
Alexandria, VA - From the tiny microcosms of atomic theory and futuristic colonies on Mars to dinosaurs walking the Earth, science illustrators translate scientific findings and theories into something lifelike, accurate and aesthetically pleasing. The July cover story from EARTH Magazine, "Science Illustrators: Making the Invisible Visible," takes readers on a behind-the-scenes of how illustrators transform a scientific concept into an informed work of art.
Scientific illustrating is informed as much by researching the scientific literature as it is by the imagination. ...
COLUMBUS, OHIO - Imagine getting a sudden boost in status at work that changes you from a largely ignored worker to someone that others turn to for advice and help.
Sounds great, doesn't it? But a new study finds that an unanticipated gain in status can come with some negative baggage - if you did not earn the boost.
Researchers studied American employees of a Japanese firm who didn't enjoy particularly high status with the company - until it adopted English as its official language. Then, all of a sudden, Japanese employees who didn't speak English had to rely a ...
Preschoolers with oppositional defiant behavior are more likely to have shorter telomeres, a hallmark of cellular aging, which in adults is associated with increased risk for chronic diseases and conditions like diabetes, obesity and cancer.
This phenomenon was uncovered by UCSF researchers, who also identified maternal clinical depression as an independent predictor for shortened telomeres in young children, according to a study published on Tuesday in the journal Translational Psychiatry.
Likened to the plastic tips of shoelaces, telomeres cap the ends of chromosomes ...
Up to 80 percent of individuals with a past history of depression will get depressed again in the future. However, little is known about the specific factors that put these people at risk. New research suggests that it may be due to the things you pay attention to in your life.
Researchers at Binghamton University recruited 160 women -- 60 with a past history of depression, 100 with no history of depression. They showed each woman a series of two faces, one with a neutral expression and the other with either an angry, sad or happy expression. Using eye-tracking, they ...
WASHINGTON - While the U.S. inland waterways system covers a vast geographic area, its freight traffic is highly concentrated, and the system needs a sustainable and well-executed plan for maintaining system reliability and performance to ensure that its limited resources are directed where they are most essential, says a new report from the National Research Council's Transportation Research Board. More targeted operations and maintenance (O&M) investments informed by an asset management approach would prioritize locks and facilities that are most in need of maintenance ...
Although most citizens tend to believe that big business owns Washington D.C., a team of researchers suggests that business may have a less dominant and more complicated relationship with government than previously thought.
In a study of randomly selected federal policy decisions between 1998 and 2002, the researchers found that when citizen interest groups and other competitors opposed businesses on policies, businesses had roughly an equal chance of success as the citizen group. When the researchers examined a shorter time period, businesses were only successful about ...
Researchers from the Johns Hopkins Bloomberg School of Public Health have located a new - and likely more promising, they say - target for a potential vaccine against malaria, a mosquito-borne illness that kills as many as 750,000 people each year.
The findings, published June 15 in the journal Nature Structural & Molecular Biology, detail how the researchers created a 3-D crystal structure of the protein believed central to the transmission of the malaria parasite through mosquitoes. In looking anew at the AnAPN1 protein, an enzyme in the gut of the Anopheles mosquito, ...
Cancer and type 2 diabetes are two of the most significant public health burdens facing the world today, and currently available data suggests their prevalence is expected to continue to increase. Nut consumption has long been hypothesized to have a role in preventing both of these diseases, but until now evidence has been inconsistent. A new systematic review and meta-analysis published in Nutrition Reviews on June 16 shows that nut consumption is, indeed, associated with a decreased risk of certain types of cancer, but not type 2 diabetes.
Researchers at the Mayo Clinic ...
This news release is available in French. Quebec City, June 16, 2015--People whose chromosomes contain the DNA of the roseola virus are three times more likely to suffer from angina, according to a new study by researchers from the Université Laval Faculty of Medicine, the CHU de Québec Research Center-Université Laval, and the University of Washington. Details of this finding are published in the latest issue of the Proceedings of the National Academy of Sciences.
Roseola, also known as "sixth disease," is a very common childhood infection caused by ...
