David Savastano, Editor09.03.14
There is plenty of research being done on printed electronics, much of it on the university level. While certainly many of these projects will not come to fruition, one never knows which idea may just be a game-changer. Here, then, are some recent announcements that show interesting potential:
• Rice University: Thin-film batteries for portable, wearable electronics are an important target for researchers, and Rice University is working on a possible solution. Rice chemist James Tour and his colleagues have created a flexible material with nanoporous nickel-fluoride electrodes layered around a solid electrolyte to deliver battery-like supercapacitor performance without lithium.
The research appears in the Journal of the American Chemical Society.
The key here is that the electrochemical capacitor is about a 100th of an inch thick. It can be scaled up by adding layers. Rice postdoctoral researcher Yang Yang, co-lead author of the paper with graduate student Gedeng Ruan, noted that standard manufacturing techniques may allow the battery to be even thinner.
“The numbers are exceedingly high in the power that it can deliver, and it’s a very simple method to make high-powered systems,” Tour said. “We’re already talking with companies interested in commercializing this.”
• Stanford University: Along the lines of thin layers, Stanford University researchers are working on flexible electronic switches that are three atoms thick.
The work was conducted by team leader Evan Reed, an assistant professor of Materials Science and Engineering; Karel-Alexander Duerloo, a Stanford Engineering graduate student; and graduate student Yao Li.
The key to this development is its ability to be used in wearable materials, and could be ideal for cell phones, for example.
Interestingly, computer simulations indicate that this thin crystal lattice can be mechanically polled and pushed like a switch. As a result of its size, it could reduce the need for battery power. The research is detailed in an article in Nature Communications.
According to Duerloo, the switchable material consists of one atomic layer of molybdenum sandwiched between two atomic layers of tellurium atoms.
“No one would have known this was possible before because they didn’t know where to look,” Duerloo said.
• Okayama University: Working in conjunction with the National Institute for Materials Science, researchers at Okayama University have created a nanoparticle ink that can be used for printing electronics without high-temperature annealing.
Because it does not require high temperature annealing, this nanoparticle ink can be printed on paper or flexible substrates that can be deformed by heat. This type of ink should also be relatively easy to produce.
Nanoparticle inks should allow simple low-cost manufacture but the nanoparticles usually used are surrounded in non-conductive ligands – molecules that are introduced during synthesis for stabilizing the particles. These ligands must be removed by annealing to make the ink conducting. The research conducted by Takeo Minari, Masayuki Kanehara and their colleagues utilized nanoparticles surrounded by planar aromatic molecules that allow charge transfer.
They used ink made of gold nanoparticles to print organic thin film transistors (OTFTs) on a flexible polymer and a paper substrate at room temperature.
• University of Michigan: Phosphorescent OLEDs, or PHOLEDs, are 100% efficient when used for smart phones, which is why this technology is already a major player in this market. However, the brighter the lighting, the less the efficiency and liefetime of PHOLEDs.
Research was conducted by Stephen Forrest, the William Gould Dow Collegiate Professor in Electrical Engineering and leader of the study, and Jaesang Lee, a University of Michigan doctoral student in electrical engineering and computer science. Lee is the first author of the study, titled “Electrophosphorescent organic light emitting concentrator,” which will be published in Light: Science and Applications.”
Lee found that PHOLEDs arranged in a pyramid do not lose efficiency, and that the pyramidal structure resulted in illumination three times brighter than a flat configuration at the same current could have offered.
“Achieving extra brightness from the conventional, flat design is inefficient and shortens the device lifetime,” said Lee. “However if we integrate our PHOLEDs into a pyramidal shape, we are able to achieve the equivalent, concentrated brightness at a much lower electrical current.”
• Rice University: In June, Rice University researchers announced they round a way to “unzip” carbon nanotubes into graphene without using chemicals. Led by graduate student Sehmus Ozden, research conducted by in the lab of materials scientist Pulickel Ajayan determined that carbon nanotubes fired into an aluminum target at 15,000 miles per hour that hit the target broadsides turn into ribbon-like materials (if they hit the target on their end they become a clump of atoms).
The key here is that the ribbons are created through mechanical force, thus eliminating the need to clean chemical residue. Their findings were reported in the American Chemical Society journal Nano Letters.
“Until now, we knew we could use mechanical forces to shorten and cut carbon nanotubes,” Ozden said. “This is the first time we have showed carbon nanotubes can be unzipped using mechanical forces.”
• Massachusetts Institute of Technology: Quantum dots are an intriguing technology, having developed opportunities in the display field. MIT researchers are utilizing quantum dots for solar cells.
This research is published in the journal Nature Materials, by MIT professors Moungi Bawendi, the Lester Wolfe Professor of Chemistry; Vladimir Bulović, the Fariborz Maseeh Professor of Emerging Technology and associate dean for innovation in MIT’s School of Engineering; and graduate students Chia-Hao Chuang and Patrick Brown.
The key here is that quantum dots are low cost and lightweight. The MIT team reached an efficiency rate of 9%, a new record although it is low compared to commercial approaches to solar cells.
By applying a thin coating of quantum dots, sunlight will be absorbed more effectively. The process for producing these cells is also less expensive that most other photovoltaic processes.
“Every part of the cell, except the electrodes for now, can be deposited at room temperature, in air, out of solution,” Chuang said. “It’s really unprecedented.”
• Massachusetts Institute of Technology and Harvard University: Researchers report they have discovered a 2-D material, a combination of nickel and an organic compound called HITP, with properties similar to graphene. This material also self-assembles.
The key here is that this material has a bandgap, which is critical of making solar cells and semiconductors.
The research, conducted by Mircea Dincă, MIT assistant professor of chemistry, and seven co-authors, was published online in the Journal of the American Chemical Society.
Dincă reports that the material has excellent electrical conductivity in bulk form, which should improve when it is flattened. This material is suitable for photovoltaics and supercapacitors.
• University of Liverpool: Researchers worldwide are looking for ways to utilize graphene, and a University of Liverpool team is analyzing how to use a new material, triazine-based graphitic carbon nitride (TGCN) related to graphene to improve transistors.
Interestingly, the researchers noted that TGCN was predicted theoretically in 1996, but this is the first time that it has been made. Much like the work conducted by MIT and Harvard noted above, this materials has a bandgap, making it possible to use in transistors. The research was published in the journal Angewandte Chemie.
“The creation and analysis of this material is just the first step,” Professor Andrew Cooper, of the University of Liverpool’s Department of Chemistry, said. “We now have a lot more work to do to scale it up and prove function in electronic devices.”
• UCLA: Thin-film transistors (TFT) are a critical material for both LCD and OLED displays. A team of researchers at UCLA, led by Yang Yang, the Carol and Lawrence E. Tannas Jr. professor of Engineering at the UCLA Henry Samueli School of Engineering and Applied Science, and You Seung Rim, a postdoctoral researcher in UCLA’s materials science and engineering department and the lead author of the research, have developed a new material and manufacturing process to create these semiconductors.
The new material is composed of indium gallium zinc oxide and indium tin zinc oxide. It offers higher mobility, which adjusts the voltage more easily. Interestingly, the materials developed by Yang’s team can be manufactured without a clean room, which the researchers compared to applying a coat of paint and baking it in an oven. The research was published in Advanced Materials.
“Our semiconductor process is faster, less expensive and more reliable than existing processes,” said Yang.
Ultimately, we do not know the commercial impact these technologies will have in the future, but they do offer interesting approaches that do have potential.
• Rice University: Thin-film batteries for portable, wearable electronics are an important target for researchers, and Rice University is working on a possible solution. Rice chemist James Tour and his colleagues have created a flexible material with nanoporous nickel-fluoride electrodes layered around a solid electrolyte to deliver battery-like supercapacitor performance without lithium.
A single macroscopic flake of TGCN. (Photo courtesy of University of Liverpool) |
The key here is that the electrochemical capacitor is about a 100th of an inch thick. It can be scaled up by adding layers. Rice postdoctoral researcher Yang Yang, co-lead author of the paper with graduate student Gedeng Ruan, noted that standard manufacturing techniques may allow the battery to be even thinner.
“The numbers are exceedingly high in the power that it can deliver, and it’s a very simple method to make high-powered systems,” Tour said. “We’re already talking with companies interested in commercializing this.”
• Stanford University: Along the lines of thin layers, Stanford University researchers are working on flexible electronic switches that are three atoms thick.
The work was conducted by team leader Evan Reed, an assistant professor of Materials Science and Engineering; Karel-Alexander Duerloo, a Stanford Engineering graduate student; and graduate student Yao Li.
The key to this development is its ability to be used in wearable materials, and could be ideal for cell phones, for example.
Interestingly, computer simulations indicate that this thin crystal lattice can be mechanically polled and pushed like a switch. As a result of its size, it could reduce the need for battery power. The research is detailed in an article in Nature Communications.
According to Duerloo, the switchable material consists of one atomic layer of molybdenum sandwiched between two atomic layers of tellurium atoms.
“No one would have known this was possible before because they didn’t know where to look,” Duerloo said.
• Okayama University: Working in conjunction with the National Institute for Materials Science, researchers at Okayama University have created a nanoparticle ink that can be used for printing electronics without high-temperature annealing.
Because it does not require high temperature annealing, this nanoparticle ink can be printed on paper or flexible substrates that can be deformed by heat. This type of ink should also be relatively easy to produce.
Nanoparticle inks should allow simple low-cost manufacture but the nanoparticles usually used are surrounded in non-conductive ligands – molecules that are introduced during synthesis for stabilizing the particles. These ligands must be removed by annealing to make the ink conducting. The research conducted by Takeo Minari, Masayuki Kanehara and their colleagues utilized nanoparticles surrounded by planar aromatic molecules that allow charge transfer.
They used ink made of gold nanoparticles to print organic thin film transistors (OTFTs) on a flexible polymer and a paper substrate at room temperature.
• University of Michigan: Phosphorescent OLEDs, or PHOLEDs, are 100% efficient when used for smart phones, which is why this technology is already a major player in this market. However, the brighter the lighting, the less the efficiency and liefetime of PHOLEDs.
Research was conducted by Stephen Forrest, the William Gould Dow Collegiate Professor in Electrical Engineering and leader of the study, and Jaesang Lee, a University of Michigan doctoral student in electrical engineering and computer science. Lee is the first author of the study, titled “Electrophosphorescent organic light emitting concentrator,” which will be published in Light: Science and Applications.”
Lee found that PHOLEDs arranged in a pyramid do not lose efficiency, and that the pyramidal structure resulted in illumination three times brighter than a flat configuration at the same current could have offered.
“Achieving extra brightness from the conventional, flat design is inefficient and shortens the device lifetime,” said Lee. “However if we integrate our PHOLEDs into a pyramidal shape, we are able to achieve the equivalent, concentrated brightness at a much lower electrical current.”
• Rice University: In June, Rice University researchers announced they round a way to “unzip” carbon nanotubes into graphene without using chemicals. Led by graduate student Sehmus Ozden, research conducted by in the lab of materials scientist Pulickel Ajayan determined that carbon nanotubes fired into an aluminum target at 15,000 miles per hour that hit the target broadsides turn into ribbon-like materials (if they hit the target on their end they become a clump of atoms).
The key here is that the ribbons are created through mechanical force, thus eliminating the need to clean chemical residue. Their findings were reported in the American Chemical Society journal Nano Letters.
“Until now, we knew we could use mechanical forces to shorten and cut carbon nanotubes,” Ozden said. “This is the first time we have showed carbon nanotubes can be unzipped using mechanical forces.”
• Massachusetts Institute of Technology: Quantum dots are an intriguing technology, having developed opportunities in the display field. MIT researchers are utilizing quantum dots for solar cells.
This research is published in the journal Nature Materials, by MIT professors Moungi Bawendi, the Lester Wolfe Professor of Chemistry; Vladimir Bulović, the Fariborz Maseeh Professor of Emerging Technology and associate dean for innovation in MIT’s School of Engineering; and graduate students Chia-Hao Chuang and Patrick Brown.
The key here is that quantum dots are low cost and lightweight. The MIT team reached an efficiency rate of 9%, a new record although it is low compared to commercial approaches to solar cells.
By applying a thin coating of quantum dots, sunlight will be absorbed more effectively. The process for producing these cells is also less expensive that most other photovoltaic processes.
“Every part of the cell, except the electrodes for now, can be deposited at room temperature, in air, out of solution,” Chuang said. “It’s really unprecedented.”
• Massachusetts Institute of Technology and Harvard University: Researchers report they have discovered a 2-D material, a combination of nickel and an organic compound called HITP, with properties similar to graphene. This material also self-assembles.
The key here is that this material has a bandgap, which is critical of making solar cells and semiconductors.
The research, conducted by Mircea Dincă, MIT assistant professor of chemistry, and seven co-authors, was published online in the Journal of the American Chemical Society.
Dincă reports that the material has excellent electrical conductivity in bulk form, which should improve when it is flattened. This material is suitable for photovoltaics and supercapacitors.
• University of Liverpool: Researchers worldwide are looking for ways to utilize graphene, and a University of Liverpool team is analyzing how to use a new material, triazine-based graphitic carbon nitride (TGCN) related to graphene to improve transistors.
Interestingly, the researchers noted that TGCN was predicted theoretically in 1996, but this is the first time that it has been made. Much like the work conducted by MIT and Harvard noted above, this materials has a bandgap, making it possible to use in transistors. The research was published in the journal Angewandte Chemie.
“The creation and analysis of this material is just the first step,” Professor Andrew Cooper, of the University of Liverpool’s Department of Chemistry, said. “We now have a lot more work to do to scale it up and prove function in electronic devices.”
• UCLA: Thin-film transistors (TFT) are a critical material for both LCD and OLED displays. A team of researchers at UCLA, led by Yang Yang, the Carol and Lawrence E. Tannas Jr. professor of Engineering at the UCLA Henry Samueli School of Engineering and Applied Science, and You Seung Rim, a postdoctoral researcher in UCLA’s materials science and engineering department and the lead author of the research, have developed a new material and manufacturing process to create these semiconductors.
The new material is composed of indium gallium zinc oxide and indium tin zinc oxide. It offers higher mobility, which adjusts the voltage more easily. Interestingly, the materials developed by Yang’s team can be manufactured without a clean room, which the researchers compared to applying a coat of paint and baking it in an oven. The research was published in Advanced Materials.
“Our semiconductor process is faster, less expensive and more reliable than existing processes,” said Yang.
Ultimately, we do not know the commercial impact these technologies will have in the future, but they do offer interesting approaches that do have potential.