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News Article | December 20, 2016
Site: www.eurekalert.org

Nanotechnology offers many chances to benefit the environment and health. It can be applied to save raw materials and energy, develop enhanced solar cells and more efficient rechargeable batteries and replace harmful substances with eco-compatible solutions. "Nanotechnology is a seminal technology. The UMWELTnanoTECH project association has delivered excellent results. Even the smallest achievements can make a huge contribution to protecting the environment. We must treat the opportunities this future technology offers with responsibility; its eco-compatible use has top priority," said the Bavarian Minister of the Environment, Ulrike Scharf, in Erlangen on 23 November 2016 where the results were presented at the international congress "Next Generation Solar Energy Meets Nanotechnology". For three years, the Bavarian State Ministry for the Environment and Consumer Protection had financed the association consisting of ten individual projects with around three million euros. Three of the ten projects were located in Würzburg. Professor Vladimir Dyakonov from the Department of Physics headed the project for environmentally compatible, highly efficient organic solar cells; he was also the spokesman of the "Organic Photovoltaics" section. Anke Krüger, Professor of Chemistry, was in charge of the project on ultra-fast electrical stores based on nano-diamond composites. Responsibility for the third project rested with Professor Gerhard Sextl, Head of the Fraunhofer Institute for Silicate Research titled "Hybrid capacitors for smart grids and regenerative energy technologies". Sextl, who holds the Chair for Chemical Technology of Material Synthesis at the Julius-Maximilians-Universität (JMU) Würzburg, was also the spokesman of the "Energy storage" section. Below are the three projects from Würzburg and their results. Organic solar cells have become quite efficient, converting about eleven percent of the solar energy received into electricity. What is more, they are relatively easy to manufacture using ink-jet printing processes where organic nanoparticles are deposited on non-elastic or flexible carrier materials with the help of solvents. This enables new applications in architecture, for example integrating solar cells in window façades or cladding concave surfaces. There is, however, a catch to it: So far, most ink-jet printing processes have been based on toxic solvents such as dichlorobenzene. These substances are harmful for humans and the environment and require extensive and costly standards of safety. The Professors Vladimir Dyakonov and Christoph Brabec (University of Erlangen-Nuremberg) have managed to use nanomaterials to develop ecologically compatible photovoltaic inks based on water or alcohol with equal efficiency. Moreover, the research team has developed new simulation processes: "They allow us to predict which combinations of solvents and materials are suitable for the eco-friendly production of organic solar cells," Dyakonov explains. To the homepage of Vladimir Dyakonov In order to build highly efficient electric cars, more powerful energy stores are needed as the standard batteries still have some drawbacks, including low cycle stability and very limited power density. The first means that the battery capacity decreases following multiple charging and discharging cycles. The latter implies that only a fraction of the energy store is used during fast charging or discharging. Supercapacitors play an important role as highly efficient energy stores besides batteries, because they outperform rechargeable batteries in terms of cycle stability and power density. Their energy density, however, is much lower compared with lithium-ion batteries. This is why supercapacitors need to be much bigger in size than batteries in order to deliver comparable amounts of energy. Professor Anke Krüger has teamed up with Dr Gudrun Reichenauer from the Bavarian Center for Applied Energy Research (ZAE Bayern) to make progress in this regard. Their idea was to build the supercapacitors' electrodes not only of active charcoal, but to modify them using other carbon materials, namely nanodiamonds and carbon onions, which are small particles that have multiple layers like an onion. Their approach is promising: By combining nanomaterials with suitable electrolytes, the performance parameters of the supercapacitors can be boosted. "Based on these findings, it is now possible to build application-oriented energy stores and test their applicability," Krüger further. To the homepage of Anke Krüger More efficient and faster energy stores were also the research focus of Professor Gerhard Sextl's project. His research team at the University of Würzburg managed to develop so-called hybrid capacitors further into highly efficient energy stores that can be manufactured in an environmentally compatible process. Hybrid capacitors are a combination of supercapacitors based on electrochemical double-layer capacitors and charge storage in a battery. Firstly, they are capable of storing energy quickly by forming an electrochemical double layer as in a supercapacitor and also deliver the energy promptly when it is needed. Secondly, they hold more energy due to lithium ions embedded in an active battery material, analogously to lithium-ion batteries. By combining the two storage mechanisms, it is possible to implement systems with a high energy and power density at low costs. The electrodes are the heart of the hybrid capacitors. They are coated with modified active materials: lithium iron phosphate and lithium titanate. This allows achieving storage capacities which are twice as high as those relying on conventional supercapacitor electrode materials. "We have managed to develop a material that combines the advantages of both systems. This has brought us one step closer to implementing a new, fast and reliable storage concept," Sextl says. The activities at the university were supported by the Fraunhofer Institute for Silicate Research in Würzburg, one of the leading battery research centres in Germany. Prof. Dr. Gerhard Sextl, Department for Chemical Technology of Material Synthesis, University of Würzburg, and Fraunhofer Institute for Silicate Research ISC, T +49 931 4100-100 To the homepage of the Fraunhofer Institute


News Article | December 21, 2016
Site: www.nanotech-now.com

Abstract: Nanotechnology offers many chances to benefit the environment and health. It can be applied to save raw materials and energy, develop enhanced solar cells and more efficient rechargeable batteries and replace harmful substances with eco-compatible solutions. "Nanotechnology is a seminal technology. The UMWELTnanoTECH project association has delivered excellent results. Even the smallest achievements can make a huge contribution to protecting the environment. We must treat the opportunities this future technology offers with responsibility; its eco-compatible use has top priority," said the Bavarian Minister of the Environment, Ulrike Scharf, in Erlangen on 23 November 2016 where the results were presented at the international congress "Next Generation Solar Energy Meets Nanotechnology". For three years, the Bavarian State Ministry for the Environment and Consumer Protection had financed the association consisting of ten individual projects with around three million euros. Three Würzburg projects Three of the ten projects were located in Würzburg. Professor Vladimir Dyakonov from the Department of Physics headed the project for environmentally compatible, highly efficient organic solar cells; he was also the spokesman of the "Organic Photovoltaics" section. Anke Krüger, Professor of Chemistry, was in charge of the project on ultra-fast electrical stores based on nano-diamond composites. Responsibility for the third project rested with Professor Gerhard Sextl, Head of the Fraunhofer Institute for Silicate Research titled "Hybrid capacitors for smart grids and regenerative energy technologies". Sextl, who holds the Chair for Chemical Technology of Material Synthesis at the Julius-Maximilians-Universität (JMU) Würzburg, was also the spokesman of the "Energy storage" section. Below are the three projects from Würzburg and their results. Eco-friendly inks for organic solar cells Organic solar cells have become quite efficient, converting about eleven percent of the solar energy received into electricity. What is more, they are relatively easy to manufacture using ink-jet printing processes where organic nanoparticles are deposited on non-elastic or flexible carrier materials with the help of solvents. This enables new applications in architecture, for example integrating solar cells in window façades or cladding concave surfaces. There is, however, a catch to it: So far, most ink-jet printing processes have been based on toxic solvents such as dichlorobenzene. These substances are harmful for humans and the environment and require extensive and costly standards of safety. The Professors Vladimir Dyakonov and Christoph Brabec (University of Erlangen-Nuremberg) have managed to use nanomaterials to develop ecologically compatible photovoltaic inks based on water or alcohol with equal efficiency. Moreover, the research team has developed new simulation processes: "They allow us to predict which combinations of solvents and materials are suitable for the eco-friendly production of organic solar cells," Dyakonov explains. Nanodiamonds for ultra-fast electrical storage In order to build highly efficient electric cars, more powerful energy stores are needed as the standard batteries still have some drawbacks, including low cycle stability and very limited power density. The first means that the battery capacity decreases following multiple charging and discharging cycles. The latter implies that only a fraction of the energy store is used during fast charging or discharging. Supercapacitors play an important role as highly efficient energy stores besides batteries, because they outperform rechargeable batteries in terms of cycle stability and power density. Their energy density, however, is much lower compared with lithium-ion batteries. This is why supercapacitors need to be much bigger in size than batteries in order to deliver comparable amounts of energy. Professor Anke Krüger has teamed up with Dr Gudrun Reichenauer from the Bavarian Center for Applied Energy Research (ZAE Bayern) to make progress in this regard. Their idea was to build the supercapacitors' electrodes not only of active charcoal, but to modify them using other carbon materials, namely nanodiamonds and carbon onions, which are small particles that have multiple layers like an onion. Their approach is promising: By combining nanomaterials with suitable electrolytes, the performance parameters of the supercapacitors can be boosted. "Based on these findings, it is now possible to build application-oriented energy stores and test their applicability," Krüger further. Increased storage capacity of hybrid capacitors More efficient and faster energy stores were also the research focus of Professor Gerhard Sextl's project. His research team at the University of Würzburg managed to develop so-called hybrid capacitors further into highly efficient energy stores that can be manufactured in an environmentally compatible process. Hybrid capacitors are a combination of supercapacitors based on electrochemical double-layer capacitors and charge storage in a battery. Firstly, they are capable of storing energy quickly by forming an electrochemical double layer as in a supercapacitor and also deliver the energy promptly when it is needed. Secondly, they hold more energy due to lithium ions embedded in an active battery material, analogously to lithium-ion batteries. By combining the two storage mechanisms, it is possible to implement systems with a high energy and power density at low costs. The electrodes are the heart of the hybrid capacitors. They are coated with modified active materials: lithium iron phosphate and lithium titanate. This allows achieving storage capacities which are twice as high as those relying on conventional supercapacitor electrode materials. "We have managed to develop a material that combines the advantages of both systems. This has brought us one step closer to implementing a new, fast and reliable storage concept," Sextl says. The activities at the university were supported by the Fraunhofer Institute for Silicate Research in Würzburg, one of the leading battery research centres in Germany. For more information, please click Contacts: Dr. Esther Knemeyer Pereira 49-931-318-6002 Eco-friendly inks for organic solar cells Prof. Dr. Vladimir Dyakonov Department of Physics University of Würzburg T +49 931 31-83111 Nanodiamonds for ultra-fast electrical storage Prof. Dr. Anke Krueger Institute of Organic Chemistry University of Würzburg T +49 931 31-85334 Increased storage capacity of hybrid capacitors Prof. Dr. Gerhard Sextl Department for Chemical Technology of Material Synthesis University of Würzburg and Fraunhofer Institute for Silicate Research ISC T +49 931 4100-100 If you have a comment, please us. Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.


Deibel C.,University of Würzburg | Dyakonov V.,University of Würzburg | Dyakonov V.,Bavarian Center for Applied Energy Research
Reports on Progress in Physics | Year: 2010

Organic solar cells have the potential to be low-cost and efficient solar energy converters, with a promising energy balance. They are made of carbon-based semiconductors, which exhibit favourable light absorption and charge generation properties, and can be manufactured by low temperature processes such as printing from solvent-based inks, which are compatible with flexible plastic substrates or even paper. In this review, we will present an overview of the physical function of organic solar cells, their state-of-the-art performance and limitations, as well as novel concepts to achieve a better material stability and higher power conversion efficiencies. We will also briefly review processing and cost in view of the market potential. © 2010 IOP Publishing Ltd.


Azimi H.,Friedrich - Alexander - University, Erlangen - Nuremberg | Hou Y.,Friedrich - Alexander - University, Erlangen - Nuremberg | Brabec C.J.,Friedrich - Alexander - University, Erlangen - Nuremberg | Brabec C.J.,Bavarian Center for Applied Energy Research
Energy and Environmental Science | Year: 2014

Solution-processed organic and inorganic semiconductors offer a promising path towards low-cost mass production of solar cells. Among the various material systems, solution processing of multicomponent inorganic semiconductors offers considerable promise due to their excellent electronic properties and superior photo- and thermal stability. This review surveys the recent developments of "all solution-processed" copper-indium (-gallium)-chalcogenide (CuInS2, CuInSe2 and Cu(In, Ga)(Se, S)2) chalcopyrites and copper-zinc-tin-chalcogenide (Cu2ZnSnS4 and Cu2ZnSnSe4 (CZTS(e))) kesterite solar cells. A brief overview further addresses some of the most critical material aspects and associated loss mechanisms in chalcopyrite and kesterite devices. Today's state-of-the-art performance as well as future challenges to achieve low-cost and environmentally friendly production is discussed. This journal is © the Partner Organisations 2014.


Rauh D.,Bavarian Center for Applied Energy Research | Deibel C.,University of Würzburg | Dyakonov V.,Bavarian Center for Applied Energy Research
Advanced Functional Materials | Year: 2012

Apparent recombination orders exceeding the value of two expected for bimolecular recombination have been reported for organic solar cells in various publications. Two prominent explanations are bimolecular losses with a carrier concentration dependent prefactor due to a trapping limited mobility and protection of trapped charge carriers from recombination by a donor-acceptor phase separation until re-emission from these deep states. In order to clarify which mechanism is dominant temperature- and illumination-dependent charge extraction measurements are performed under open circuit and short circuit conditions at poly(3-hexylthiophene-2,5-diyl):[6,6]-phenyl-C 61 butyric acid methyl ester (P3HT:PC 61BM) and PTB7:PC 71BM (poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b]dithiophene-2,6-diyl] [3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl]]) solar cells in combination with current-voltage characteristics. It is shown that the charge carrier density n dependence of the mobility μ and the recombination prefactor are different for P3HT:PC 61BM at temperatures below 300 K and PTB7:PC 71BM at room temperature. Therefore, in addition to μ(n), a detrapping limited recombination in systems with at least partial donor-acceptor phase separation is required to explain the high recombination orders. It is shown that the often reported recombination orders, which are higher than two for organic photovoltaic solar cells, cannot be explained by the charge carrier density, n, dependence of the mobility, μ, alone, as the Langevin recombination prefactor k exhibits a different n dependence than μ. The discrepancy is explained by a more complex recombination process including trap states and phase separation. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Ameri T.,Friedrich - Alexander - University, Erlangen - Nuremberg | Khoram P.,Friedrich - Alexander - University, Erlangen - Nuremberg | Min J.,Friedrich - Alexander - University, Erlangen - Nuremberg | Brabec C.J.,Friedrich - Alexander - University, Erlangen - Nuremberg | Brabec C.J.,Bavarian Center for Applied Energy Research
Advanced Materials | Year: 2013

Recently, researchers have paid a great deal of attention to the research and development of organic solar cells, leading to a breakthrough of over 10% power conversion efficiency. Though impressive, further development is required to ensure a bright industrial future for organic photovoltaics. Relatively narrow spectral overlap of organic polymer absorption bands within the solar spectrum is one of the major limitations of organic solar cells. Among different strategies that are in progress to tackle this restriction, the novel concept of ternary organic solar cells is a promising candidate to extend the absorption spectra of large bandgap polymers to the near IR region and to enhance light harvesting in single bulk-heterojunction solar cells. In this contribution, we review the recent developments in organic ternary solar cell research based on various types of sensitizers. In addition, the aspects of miscibility, morphology complexity, charge transfer dynamics as well as carrier transport in ternary organic composites are addressed. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Ameri T.,Friedrich - Alexander - University, Erlangen - Nuremberg | Li N.,Friedrich - Alexander - University, Erlangen - Nuremberg | Brabec C.J.,Friedrich - Alexander - University, Erlangen - Nuremberg | Brabec C.J.,Bavarian Center for Applied Energy Research
Energy and Environmental Science | Year: 2013

Multi-junction solar cell configurations, where two or further sub-cells with complementary absorption are stacked and connected in series or parallel, offer an exciting approach to tackle the single junction limitations of organic solar cells and further improve their power conversion efficiency. In this article we aim to follow up our previous work and review the most important and novel developments that have been recently reported on organic tandem solar cells. In addition, some brief theoretical considerations addressing the potential of single and tandem solar cells, the working principles of the intermediate layer, the importance and benefits of optical simulations and finally the intricacies of a precise performance measurement of bulk-heterojunction organic tandem solar cells based on complementary absorber materials are presented. © 2013 The Royal Society of Chemistry.


Latent heat storage with materials undergoing a phase change solid-liquid is gaining increasing interest due to its potential for applications in energy systems. The demand for optimized storage materials has led to an intensification of materials research in recent years. The research focuses mainly on developing materials with high storage density, and related to this the question what the theoretical limit is. For both it is necessary to understand what affects the melting enthalpy and melting temperature on the atomic and molecular level. For some material classes, especially metals, empiric rules or microscopic models have been developed that allow a qualitative and sometimes a rough quantitative prediction of the melting enthalpy and melting temperature. However, none of them is applicable to a wide variety of material classes or gives a general insight in the parameters affecting the melting enthalpy and melting temperature. In this paper, data of the elements with atomic number 1-95, and therefore very different material classes, are analyzed. In contrast to previous investigations, the focus is on relations between melting enthalpy and melting entropy, because these values relate to the microscopic structure. The results of the analysis show that several clusters exist among the elements. The differences between these clusters in the melting enthalpy as well as in the melting entropy can largely be explained by the microscopic structure of their member elements. © 2012.


Hauer A.,Bavarian Center for Applied Energy Research
Chemie-Ingenieur-Technik | Year: 2011

Open adsorption systems using water as adsorbate, zeolite as adsorbent and air as heat and mass carrier can be used for heating, cooling and thermal energy storage (TES). In an adsorption cycle air is dehumidified, so drying processes are a promising field of application. The objective of the work presented was to reduce the energy consumption of a dishwasher by means of an open adsorption system. The water heating phase of the main washing cycle has been used to desorb a packed bed of zeolites. The common water heating phase before the drying of the dishes has been omitted and replaced by an adsorption phase in which the dishes are dried by hot air. In this context the adsorption system was used as a thermally driven heat pump and a thermal energy storage system. The energy consumption is reduced by 25 % compared to a conventional dishwasher. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


News Article | October 27, 2015
Site: www.renewableenergyworld.com

Researchers at the Technical University of Munich (TUM), Kraftwerke Haag GmbH, VARTA Storage GmbH and the Bavarian Center for Applied Energy Research (ZAE-Bayern) on Oct. 18 launched a field test for a new stationary intermediate energy storage system – the Energy Neighbor.

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