Nano-sized metallic wires are attracting increasing attention as conductive elements for manufacturing transparent electrodes, which are employed in solar cells and touch screen panels. In addition to high electric conductivity, excellent optical transmittance is one of the important parameters for an electrode in photovoltaic applications.
An international team headed by HZB scientist Prof. Michael Giersig has recently demonstrated for these applications that networks of metallic mesh possessing fractal-like nano-features surpass other metallic networks in utility. These findings have now been published in the most recent edition of the renowned journal Nature Communications.
Their new development is based on what is termed quasi-fractal nano-features. These structures have similarities to the hierarchical networks of veins in leaves. Giersig’s team was able to show that metallic networks with these features optimise performance of electrodes for several applications.
They combine minimized surface coverage with ultra-low total resistance while maintaining uniform current density. In addition, it was demonstrated that these networks, inspired by nature, can surpass the performance of conventional indium tin oxide (ITO) layers.
In experiments on artificially constructed electrode networks of different topologies, the scientists established that non-periodic hierarchical organisation exhibited lower resistance as well as excellent optical transmittance in comparison to periodic organisation. This led to elevated output power for photovoltaic components.
“On the basis of our studies, we were able to develop an economical transparent metal electrode", says Giersig, continuing “We obtain this by integrating two silver networks. One silver network is applied with a broad mesh spacing between the micron-diameter main conductors that serve as the “highway" for electrons transporting electrical current over macroscopic distances.”
Next to it, additional randomly distributed nano-wire networks serve as local conductors to cover the surface between the large mesh elements. “These smaller networks act as regional roadways beside the highways to randomise the directions and strengths of the local currents, and also create refraction effects to improve transparency above that of classical shadow-limited performance”, according to Giersig. “Solar cells based upon these electrodes show exceptional a high efficiencies”.
Publication: Optimization of hierarchical structure and nanoscale-enabled plasmonic refraction for window electrodes in photovoltaics; Nature Communications, 7, 12825; doi:10.1038/ncomms12825
Prof. Dr. Michael Giersig
Dr. Ina Helms | Helmholtz-Zentrum Berlin für Materialien und Energie GmbH
Studying fundamental particles in materials
17.01.2017 | Max-Planck-Institut für Struktur und Dynamik der Materie
Seeing the quantum future... literally
16.01.2017 | University of Sydney
Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales
Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...
Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.
As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...
At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).
Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...
Many pathogens use certain sugar compounds from their host to help conceal themselves against the immune system. Scientists at the University of Bonn have now, in cooperation with researchers at the University of York in the United Kingdom, analyzed the dynamics of a bacterial molecule that is involved in this process. They demonstrate that the protein grabs onto the sugar molecule with a Pac Man-like chewing motion and holds it until it can be used. Their results could help design therapeutics that could make the protein poorer at grabbing and holding and hence compromise the pathogen in the host. The study has now been published in “Biophysical Journal”.
The cells of the mouth, nose and intestinal mucosa produce large quantities of a chemical called sialic acid. Many bacteria possess a special transport system...
UMD, NOAA collaboration demonstrates suitability of in-orbit datasets for weather satellite calibration
"Traffic and weather, together on the hour!" blasts your local radio station, while your smartphone knows the weather halfway across the world. A network of...
10.01.2017 | Event News
09.01.2017 | Event News
05.01.2017 | Event News
17.01.2017 | Earth Sciences
17.01.2017 | Machine Engineering
17.01.2017 | Physics and Astronomy