Blu-ray disc pattern helps solar cells absorb more light

Blu-ray Disc is known for its high storage capacity and high quality audio and video. Recently, however, the research team of Huang Jiaxing, an associate professor of materials science and engineering at Northwestern University in the United States, found that only using Blu-ray discs to see the film was too queasy - they printed the data on the Blu-ray discs of the film on solar cells. The cells can absorb more light and the conversion efficiency (light energy converted to electrical energy) is increased by 22%. The study was published in the magazine Nature Communications.

Huang Jiaxing's team has tried various Blu-ray discs. Whatever the video content, it can increase the solar cell's light absorption rate. The secret lies in the etching pattern of the Blu-ray Disc.

Secrets in Blu-ray Disc

The study found that the secret to increasing the light absorption rate is hidden in the information code of Blu-ray discs. The principle of Blu-ray discs is similar to that of ordinary DVD discs. Different lengths of pits are etched on the disc to represent binary values. "and 1". When reading the data, the laser light shines on different pits to reflect different lasers, and the light monitor reads the data.

The data processing algorithm used by Blu-ray discs when recording data has two characteristics: When suppressing binary video information, "0" and "1" are randomly arranged; in order to prevent the disc from being scratched or fingerprinted, it is burned. In the case of a disc, a duplicate error control code is added every few valid bytes.

The lines made up of random code and regular error control codes make a special pattern on the Blu-ray Disc --- a quasi-random pattern. In addition, these small pits on Blu-ray discs are much denser than ordinary DVDs. The pits representing “0” and “1” are 150 nanometers and 525 nanometers respectively. This nano-sized structure is just perfect for capturing. The entire solar spectrum of light.

Quasi-random pattern of magic

Why is it more efficient to print a quasi-random pattern than a random pattern or an unprocessed cell? The researchers compared regular patterns, random patterns, quasi-random patterns, and patterns on Blu-ray discs.

Through experiments, the researchers found that the quasi-random pattern is very close to the Blu-ray disc pattern. Both of them can “catch” all the light spots, but the regular patterns cannot, and completely random patterns also miss a lot.

Therefore, the Blu-ray disc pattern can help solar cells absorb more light.

How to make

In solar cells, the active layer is responsible for capturing photons. The nanostructures of the active layer affect the ability to absorb light. The researchers first peeled off the upper plastic layer of the Blu-ray disc, covered the disc with "silk" material, and pressed the seal onto the previously prepared active layer. Using this method, researchers increased the conversion efficiency of organic cells by nearly 22%.

In the field of solar cell research, researchers have been looking for ways to improve the surface structure of the cell in order to increase the conversion efficiency of the cell, but also to minimize production costs. Making a quasi-random pattern of nanostructured templates is troublesome, and Blu-ray discs provide ready-made templates. Therefore, the production method of the Huang Jiaxing team not only effectively improves the efficiency of battery conversion, but also has a low production cost. .

Ion Cannon

Solar cell

Twin Creeks, a US company that specializes in research and development of solar and semiconductor ultra-thin wafer technologies, revealed that they have developed a solar cell that costs half as much as the world’s cheapest products. Even better, solar cells are manufactured using particle accelerators. from.

It is reported that the company's "Hybiron 3" particle accelerator emits silicon wafers of extremely thin solar cells by emitting hydrogen ions to bombard silicon plates.

Currently, almost all solar panels cut a large block of crystalline silicon into a 200-micron-thick silicon wafer, add the electrode plates, encapsulate it with a glass lid, and place it in a place where there is sunlight through the photoelectric effect. (When a photon strikes silicon, it excites electrons, produces electricity, and converts light energy into electricity). There are two major drawbacks to this approach: Just as cutting wood produces wood chips, when the crystalline silicon block is divided into 200-micron crystalline silicon wafers, “silicon swarf” is also generated, causing waste, and this waste is close to 50%; In addition, even if the thickness is less than 200 microns, the panel can work well on the surface, but the wafer becomes too fragile or even broken due to its thinness.

The "Hybiron 3" particle accelerator emits hydrogen ions onto these silicon wafers. The voltage of the accelerator is strictly controlled, and hydrogen ions are emitted so as to be accumulated to a depth of 20 microns on the surface of the silicon wafer. The wafers are transported by a robot to a furnace where hydrogen ions on the surface of the wafer are heated to hydrogen in the furnace, thus separating the 20-micron-thick silicon layer. The substrate is made of metal, making it unbreakable. The remaining silicon wafers can be used by the particle accelerator to emit hydrogen ions again. The thickness is reduced to 1/10, reducing wafer waste.

Trees

Solar cell

Researchers from Georgia Tech and Purdue University have developed new types of high-efficiency solar cells. The materials used to make batteries come from natural plants, such as trees everywhere. At the same time, these solar cells can be quickly recycled after they have been used for life by soaking them in water.

According to researchers, the power conversion efficiency of this organic solar cell has reached 2.7%, which is far higher than other solar cells using renewable raw materials as substrates.

The researchers said that the cellulose nanocrystal substrates used to assemble solar cells are optically transparent, allowing light to pass through them and being absorbed by a thin layer of organic semiconductors. In the recycling process, as long as the solar cell is immersed in water at room temperature, the substrate will dissolve in only a few minutes, and the battery itself can be easily separated.

optical fiber

Solar cell

A team of engineers, physicists and chemists from around the world has produced the world’s first optical fiber solar cell. These optical fibers have a smaller diameter than human hair and are soft and flexible. They also have the ability to generate electricity from solar cells.

The U.S. military has already become interested in this wonderful product and is preparing to use it as a mixed fabric for military clothing. The future American soldier is likely to wear a battery on the battlefield.

It is understood that this kind of solar cell is essentially a vitreous fiber. Scientists use high-pressure chemical vapor deposition technology to implant n-type, i-type, and p-type amorphous silicon into an optical fiber, giving it the function of a solar cell. Functionally, optical fibers implanted with amorphous silicon are no different from ordinary solar cells. The difference is that people attach amorphous silicon to a flat glass substrate when manufacturing traditional solar cells, making the product naturally as hard as glass; while optical fiber solar cells break through the limits of the plane when implanting silicon. Also because of the difference in material, soft properties are obtained.

The researchers said that they have already made "a few meters long fiber optic solar cells" and their new technology can produce "fiber optic solar cells with a length of more than ten meters." If the length of the fiber optic solar cell can reach this level, the remaining problem is to weave it into the clothes.

These fiber-optic solar cells still have many functions worth exploring. Because it breaks through the plane of silicon attachment, the solar cell has no distinction between the front and the back. Light from any angle can produce electrical energy, and it will not attenuate efficiency with the change of light angle.

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