Photovoltaics continues to be an expensive technology. Dye-based solar cells may represent a more cost-effective alternative to traditional solar cells. In these cells, a dye is used in place of a semiconductor to trap the light.
Tandem cells consisting of both a conventional n-type and an “inverse” p-type dye-sensitized solar cell seem to be especially promising. In the journal Angewandte Chemie, a team of Australian and German scientists has now reported a significant increase in the degree of efficiency of p-type dye-sensitized solar cells through use of an electrolyte based on a cobalt complex.
Conventional n-type dye-sensitized solar cells use a photoanode, a positive electrode coated with an n-type semiconductor, such as titanium dioxide, and a dye. When light strikes the electrode, the dye molecules become excited and release electrons—negative charges, hence the n in n-type—and “inject” them into the n-type semiconductor.
The redox mediator, a component of the electrolyte that can move freely between the electrodes, regenerates the dye by resupplying it with electrons from the counter electrode. In a p-type cell, the process is reversed: a special dye and a p-type semiconductor are located on a photocathode.
The light-activated dye “sucks” electrons out of the valence band of a p-type semiconductor such as nickel oxide. This effectively transfers “electron holes”—positive charges, hence the p in p-type—from the dye. The redox mediator takes the electrons from the dye and hands them over to the counter electrode.
A very promising approach for increasing the performance of photovoltaic cells is to combine both an n-type and a p-type dye-sensitized solar cell to make a tandem cell. However, despite some progress, the performance of the p-type cells still significantly lags behind that of their n-type counterparts. An international team of researchers from Monash University and the Commonwealth Scientific and Industrial Research Organization (Australia), as well as the University of Ulm (Germany), have now achieved a considerable improvement in the efficiency of p-type cells by choosing a different redox mediator.
Researchers working with Udo Bach and Leone Spiccia replaced the previous, commonly used iodide and triiodide system with a well-known cobalt complex, tris(ethylenediamine)cobalt(II)/(III), in which the cobalt can switch between the +2 and +3 oxidation states. The advantage of this system is that the redox potential is significantly lower. As a result, the open-circuit voltage, a critical parameter for solar cells, is doubled and there is still a high enough driving force to ensure rapid and efficient regeneration of the spent dye.These devices achieve an energy-conversion efficiency of 1.3 %, while previous systems attained a maximum of only 0.41 %. The p-type dye-sensitized solar cell with the cobalt-based redox mediator even gave promising performance data under diffuse sunlight experienced on cloudy days.
Angewandte Chemie International Edition, Permalink to the article: http://dx.doi.org/10.1002/anie.201206219
Udo Bach | Angewandte Chemie
First time-lapse footage of cell activity during limb regeneration
25.10.2016 | eLife
Phenotype at the push of a button
25.10.2016 | Institut für Pflanzenbiochemie
Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion
Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...
Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.
"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...
In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.
A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...
By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.
"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...
COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.
In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...
14.10.2016 | Event News
14.10.2016 | Event News
12.10.2016 | Event News
25.10.2016 | Earth Sciences
25.10.2016 | Life Sciences
25.10.2016 | Earth Sciences