Mohammad ALHADDAD

WASHINGTON - Engineers at the University of Washington have developed what they believe to be more stable, less toxic semiconductors for solar applications using new pyrufsecurity, according to a study published on July 26 in the journal Chemical of Materials.

Most efficient
The new semiconductors discovered by the research team consist of potassium, barium, telorium, bismuth and oxygen. Lead-free pyrophysic acid was one of 30,000 bismuth-based oxides.

The biophysics are semiconductors used in many applications. Currently, most solar cells are manufactured using silicon crystals, a relatively pure and effective material for this purpose. However, pyrofscate devices provide higher conversion efficiency than silicon.

Using information systems and quantum mechanical calculations on one of the world's fastest-growing computers, Arashdip Singh Thind, a doctoral student at the Mishra lab based in Oak Ridge National Laboratory, found that KBaTeBiO6 was the most efficient of 30,000 possible oxide semiconductors.

More stable
The researchers found that this compound appears to be the most stable and can be manufactured in the laboratory. Most importantly, the researchers said that this compound has fairly good properties and is expected to have a smaller gap in the range, where most oxides tend to have a large range.

The band gap is an area of ​​energy that electrons can not penetrate. It can be considered as the energy barrier that electrons must overcome to form free vectors that, in the context of a solar cell, can be extracted to operate an electrical device or store it in a battery.

Energy is available to overcome this barrier by sunlight. According to the study, the most promising compounds for solar cell applications have a band gap of about 1.5 electron volts.

The new material is synthesized and manufactured with stability, and has a band gap of 1.88 electron volts, higher than other oxides.

The first-generation solar cells need better control of the band gap, but they are a good first step toward harmless solar cells, and open up a great deal of semiconductor design not only for solar cell applications but also for other semiconductor applications such as LCD screens.

Black and yellow crystals
Another new study by researchers from the Catholic University of Louvain in Belgium - for the first time - a way to fix a promising type of man-made pyrophysic crystals - can turn sunlight into electricity.

As a result, the crystals turn black, allowing them to absorb sunlight. The study was published on July 26 in the journal Science.

The only problem facing them is that some of the most promising pyrofxcate materials such as "Theodoric Lead Cesium" are very unstable at room temperature.

In these circumstances, the color is yellow, since the atoms in the crystal do not form the pyrophysic structure. In order for crystals to absorb sunlight efficiently and convert it into electricity, it must be in the case of black pyrophysics, and remain so.

According to the study, silicon is a very strong crystalline crystal, if pressed it will not change shape. On the other hand, the pyrufskite is softer and more resilient.

The team found that by connecting thin films of pyrophysic solar cells with a layer of glass, the cells could obtain and maintain their desired black state.

The film is heated to a temperature of 330 ° C, which causes the peruvian expansion and adhesion to the glass. After heating, the film layer is cooled rapidly to room temperature. This process stabilizes the atoms in the crystals and restricts their movement so that they remain in the desired black shape.