First superconducting graphene created

Graphene, the ultra-thin, ultra-strong material made from a single layer of carbon atoms, just got a little more extreme. University of British Columbia (UBC) physicists have been able to create the first ever superconducting graphene sample by coating it with lithium atoms. Although superconductivity has already been observed in intercalated bulk graphite—three-dimensional crystals layered with alkali metal atoms, based on the graphite used in pencils—inducing superconductivity in single-layer graphene has until now eluded scientists. University of British Columbia physicists have been able to create the first superconducting graphene sample by coating it with lithium atoms. “Decorating monolayer graphene with a layer of lithium atoms enhances the graphene’s electron–phonon coupling to the point where superconductivity can be induced,” says Andrea Damascelli, director of UBC’s Quantum Matter Institute and lead scientist of the study outlining the discovery ("Evidence for superconductivity in Li-decorated graphene"). Graphene, roughly 200 times stronger than steel by weight, is a single layer of carbon atoms arranged in a honeycomb pattern. Along with studying its extreme physical properties, scientists eventually hope to make very fast transistors, semiconductors, sensors and transparent electrodes using graphene. “This is an amazing material,’” says Bart Ludbrook, first author on the paper and a former PhD researcher in Damascelli’s group at UBC. “Decorating monolayer graphene with a layer of lithium atoms enhances the graphene’s electron–phonon coupling to the point where superconductivity can be stabilized.” Given the massive scientific and technological interest, the ability to induce superconductivity in single-layer graphene promises to have significant cross-disciplinary impacts. According to financial reports, the global market for graphene reached $9 million in 2014 with most sales in the semiconductor, electronics, battery, energy, and composites industries. The researchers, which include colleagues at the Max Planck Institute for Solid State Research through the joint Max-Planck-UBC Centre for Quantum Materials, prepared the Li-decorated graphene in ultra-high vacuum conditions and at ultra-low temperatures (5 K or -449 F or -267 C), to achieve this breakthrough.

read more "First superconducting graphene created"

Novel efficient and low-cost semitransparent perovskite solar cells with graphene electrodes

Developing transparent or semitransparent solar cells with high efficiency and low cost to replace the existing opaque and expensive silicon-based solar panels has become increasingly important due to the increasing demands of the building integrated photovoltaics (BIPVs) systems. The Department of Applied Physics of The Hong Kong Polytechnic University (PolyU) has successfully developed efficient and low-cost semitransparent perovskite solar cells with graphene electrodes ("Efficient Semitransparent Perovskite Solar Cells with Graphene Electrodes,"). The power conversion efficiencies (PCEs) of this novel invention are around 12% when they are illuminated from Fluorine-doped Tin Oxide bottom electrodes (FTO) or the graphene top electrodes, compared with 7% of conventional semitransparent solar cells. Its potential low cost of less than HK$0.5/Watt, more than 50% reduction compared with the existing cost of Silicon solar cells, will enable it to be widely used in the future. Semitransparent perovskite solar cells with graphene electrodes. (Image: The Hong Kong Polytechnic University) Solar energy is an important source of renewable energy, in which solar cell will be used to convert light energy directly into electricity by photovoltaic effect. The first generation crystalline silicon solar panel is highly stable with efficient energy conversion, but opaque and expensive. The second generation solar cell, namely thin film solar cell, is light in weight and can be made flexible. However, they are made of rare materials with complicated structure and need high temperature treatments. With the research objectives of producing solar panels of high PCEs, easy fabrication, and low cost, in recent years, scientists have been investigating third generation solar cells. Perovskite solar cell as a novel third generation solar cell has attracted much attention recently due to its high power conversion efficiency, convenient fabrication process and potentially low cost. With the aim of improving PCEs and reducing costs of semitransparent solar panels, PolyU researcher has developed the first-ever made semitransparent perovskite solar cells with graphene as electrode. Graphene is an ideal candidate for transparent electrodes in solar cells with high transparency, good conductivity and potentially low cost. The semitransparent feature of the solar cell enables it to absorb light from both sides, and can be widely used in windows, facades, louvers and rooftops of buildings for converting solar energy into electricity, thus increasing the surface area for collecting solar energy substantially. While graphene as an advanced material was invented more than 10 years ago, PolyU innovated simple processing techniques for enhancing the conductivity of graphene to meet the requirement of its applications in solar cells. Firstly, the conductivity of graphene was dramatically improved by coating a thin layer of conductive polymer poly-(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS), that was also used as an adhesion layer to the perovskite active layer during the lamination process. Secondly, to further improve the efficiency of power conversion, PolyU researcher found that by fabricating the solar cell with multilayer chemical vapor deposition graphene as top transparent electrodes, the sheet resistance of the electrode could be further reduced while maintaining the high transparency of the electrodes. Lastly, the performance of this novel invention is further optimized by improving the contact between the top graphene electrodes and the hole transport layer (spiro-OMeTAD) on the perovskite films. Because of the excellent mechanical flexibility of graphene and the convenient preparation of the devices, PolyU's invention can be used for the mass production of the semitransparent perovskite solar cells with printing or roll to roll process. The semitransparent solar cells will fill the gap in the market which is not achievable by the existing solar cells dominating the market.

read more "Novel efficient and low-cost semitransparent perovskite solar cells with graphene electrodes"

Researchers create super-stretchable metallic conductors for flexible electronics

Washington State University researchers have discovered how to stretch metal films used in flexible electronics to twice their size without breaking. The discovery could lead to dramatic improvements and addresses one of the biggest challenges in flexible electronics, an industry still in its infancy with applications such as bendable batteries, robotic skins, wearable monitoring devices and sensors, and connected fabrics. The work was led by Rahul Panat and Indranath Dutta, researchers in Voiland College's School of Mechanical and Materials Engineering, and graduate student Yeasir Arafat. They have filed for a patent and published their findings in ("Super-stretchable metallic interconnects on polymer with a linear strain of up to 100%"). Stretching a struggle Researchers have struggled for years with designing and manufacturing the tiny metal connections that go into flexible electronics. The metal has to undergo severe stretching and bending while continuing to conduct electricity. Manufacturers have so far used tiny metal springs that can stretch and still maintain connectivity, but the springs take up space and make it difficult to design complicated, high-density circuitry. Furthermore, electricity has to travel farther in coiled springs, requiring more power and bigger batteries. "The circuitry ends up requiring a ton of real estate and bulky batteries," said Panat. Researchers have experimented with gold, which works better than other materials but is prohibitively expensive, and copper, which severely cracks when it is stretches more than 30 percent or so. A quantum improvement The WSU researchers found that when they made a metal film out of indium, a fairly inexpensive metal compared to gold, and periodically bonded it to a plastic layer commonly used in electronics, they were able to stretch the metal film to twice its original length. When the pieces broke, it was actually the plastic layer that failed, not the metal. "This is a quantum improvement in stretchable electronics and wearable devices," said Panat. While Panat is excited about the work and hopes it will be commercialized, the researchers also want to better understand the metal's behavior. "A metal film doubling its size and not failing is very unusual,'' he said. "We have proposed a model for the stretchy metal but much work is needed to validate it. It's a good situation to be in.''

read more "Researchers create super-stretchable metallic conductors for flexible electronics"

Researchers create super-stretchable metallic conductors for flexible electronics

Washington State University researchers have discovered how to stretch metal films used in flexible electronics to twice their size without breaking. The discovery could lead to dramatic improvements and addresses one of the biggest challenges in flexible electronics, an industry still in its infancy with applications such as bendable batteries, robotic skins, wearable monitoring devices and sensors, and connected fabrics. The work was led by Rahul Panat and Indranath Dutta, researchers in Voiland College's School of Mechanical and Materials Engineering, and graduate student Yeasir Arafat. They have filed for a patent and published their findings in ("Super-stretchable metallic interconnects on polymer with a linear strain of up to 100%"). Stretching a struggle Researchers have struggled for years with designing and manufacturing the tiny metal connections that go into flexible electronics. The metal has to undergo severe stretching and bending while continuing to conduct electricity. Manufacturers have so far used tiny metal springs that can stretch and still maintain connectivity, but the springs take up space and make it difficult to design complicated, high-density circuitry. Furthermore, electricity has to travel farther in coiled springs, requiring more power and bigger batteries. "The circuitry ends up requiring a ton of real estate and bulky batteries," said Panat. Researchers have experimented with gold, which works better than other materials but is prohibitively expensive, and copper, which severely cracks when it is stretches more than 30 percent or so. A quantum improvement The WSU researchers found that when they made a metal film out of indium, a fairly inexpensive metal compared to gold, and periodically bonded it to a plastic layer commonly used in electronics, they were able to stretch the metal film to twice its original length. When the pieces broke, it was actually the plastic layer that failed, not the metal. "This is a quantum improvement in stretchable electronics and wearable devices," said Panat. While Panat is excited about the work and hopes it will be commercialized, the researchers also want to better understand the metal's behavior. "A metal film doubling its size and not failing is very unusual,'' he said. "We have proposed a model for the stretchy metal but much work is needed to validate it. It's a good situation to be in.''

read more "Researchers create super-stretchable metallic conductors for flexible electronics"

Novel efficient and low-cost semitransparent perovskite solar cells with graphene electrodes

Developing transparent or semitransparent solar cells with high efficiency and low cost to replace the existing opaque and expensive silicon-based solar panels has become increasingly important due to the increasing demands of the building integrated photovoltaics (BIPVs) systems. The Department of Applied Physics of The Hong Kong Polytechnic University (PolyU) has successfully developed efficient and low-cost semitransparent perovskite solar cells with graphene electrodes ("Efficient Semitransparent Perovskite Solar Cells with Graphene Electrodes,"). The power conversion efficiencies (PCEs) of this novel invention are around 12% when they are illuminated from Fluorine-doped Tin Oxide bottom electrodes (FTO) or the graphene top electrodes, compared with 7% of conventional semitransparent solar cells. Its potential low cost of less than HK$0.5/Watt, more than 50% reduction compared with the existing cost of Silicon solar cells, will enable it to be widely used in the future. Semitransparent perovskite solar cells with graphene electrodes. (Image: The Hong Kong Polytechnic University) Solar energy is an important source of renewable energy, in which solar cell will be used to convert light energy directly into electricity by photovoltaic effect. The first generation crystalline silicon solar panel is highly stable with efficient energy conversion, but opaque and expensive. The second generation solar cell, namely thin film solar cell, is light in weight and can be made flexible. However, they are made of rare materials with complicated structure and need high temperature treatments. With the research objectives of producing solar panels of high PCEs, easy fabrication, and low cost, in recent years, scientists have been investigating third generation solar cells. Perovskite solar cell as a novel third generation solar cell has attracted much attention recently due to its high power conversion efficiency, convenient fabrication process and potentially low cost. With the aim of improving PCEs and reducing costs of semitransparent solar panels, PolyU researcher has developed the first-ever made semitransparent perovskite solar cells with graphene as electrode. Graphene is an ideal candidate for transparent electrodes in solar cells with high transparency, good conductivity and potentially low cost. The semitransparent feature of the solar cell enables it to absorb light from both sides, and can be widely used in windows, facades, louvers and rooftops of buildings for converting solar energy into electricity, thus increasing the surface area for collecting solar energy substantially. While graphene as an advanced material was invented more than 10 years ago, PolyU innovated simple processing techniques for enhancing the conductivity of graphene to meet the requirement of its applications in solar cells. Firstly, the conductivity of graphene was dramatically improved by coating a thin layer of conductive polymer poly-(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS), that was also used as an adhesion layer to the perovskite active layer during the lamination process. Secondly, to further improve the efficiency of power conversion, PolyU researcher found that by fabricating the solar cell with multilayer chemical vapor deposition graphene as top transparent electrodes, the sheet resistance of the electrode could be further reduced while maintaining the high transparency of the electrodes. Lastly, the performance of this novel invention is further optimized by improving the contact between the top graphene electrodes and the hole transport layer (spiro-OMeTAD) on the perovskite films. Because of the excellent mechanical flexibility of graphene and the convenient preparation of the devices, PolyU's invention can be used for the mass production of the semitransparent perovskite solar cells with printing or roll to roll process. The semitransparent solar cells will fill the gap in the market which is not achievable by the existing solar cells dominating the market.

read more "Novel efficient and low-cost semitransparent perovskite solar cells with graphene electrodes"

First superconducting graphene created

Graphene, the ultra-thin, ultra-strong material made from a single layer of carbon atoms, just got a little more extreme. University of British Columbia (UBC) physicists have been able to create the first ever superconducting graphene sample by coating it with lithium atoms. Although superconductivity has already been observed in intercalated bulk graphite—three-dimensional crystals layered with alkali metal atoms, based on the graphite used in pencils—inducing superconductivity in single-layer graphene has until now eluded scientists. University of British Columbia physicists have been able to create the first superconducting graphene sample by coating it with lithium atoms. “Decorating monolayer graphene with a layer of lithium atoms enhances the graphene’s electron–phonon coupling to the point where superconductivity can be induced,” says Andrea Damascelli, director of UBC’s Quantum Matter Institute and lead scientist of the study outlining the discovery ("Evidence for superconductivity in Li-decorated graphene"). Graphene, roughly 200 times stronger than steel by weight, is a single layer of carbon atoms arranged in a honeycomb pattern. Along with studying its extreme physical properties, scientists eventually hope to make very fast transistors, semiconductors, sensors and transparent electrodes using graphene. “This is an amazing material,’” says Bart Ludbrook, first author on the paper and a former PhD researcher in Damascelli’s group at UBC. “Decorating monolayer graphene with a layer of lithium atoms enhances the graphene’s electron–phonon coupling to the point where superconductivity can be stabilized.” Given the massive scientific and technological interest, the ability to induce superconductivity in single-layer graphene promises to have significant cross-disciplinary impacts. According to financial reports, the global market for graphene reached $9 million in 2014 with most sales in the semiconductor, electronics, battery, energy, and composites industries. The researchers, which include colleagues at the Max Planck Institute for Solid State Research through the joint Max-Planck-UBC Centre for Quantum Materials, prepared the Li-decorated graphene in ultra-high vacuum conditions and at ultra-low temperatures (5 K or -449 F or -267 C), to achieve this breakthrough.

read more "First superconducting graphene created"