Scientists have created dual solar cells like 'sandwich'

By combining the perovskite with traditional silicon batteries, engineers have increased the efficiency of solar cells.

Perovskite , the common name of ceramic materials has a crystal structure similar to that of calcium titanate (CaTiO ₃ ), a promising material for creating solar cells.

The perovskite " consortium" that inherently absorbs energy-rich green photons from sunlight, with a standard silicon layer has good absorption properties of light rays containing low energy levels.

In theory, such a parallel double-layer battery structure can provide an energy intensity that is twice the normal level. But the construction of two complete solar panels with one layer on top of the other will increase production costs and pose many other challenges. A team in the United States has announced a step forward in finding a method with a simpler and more economical potential for making this type of dual solar cell.

Perovskite plays a role in the transformation of light instead of generating energy.

In the study of this group, perovskite plays a role in converting light instead of generating energy, which is responsible for transforming blue photons into near-infrared (near-IR photons) photons that then pin The silicon underneath will convert them into energy. The researchers said that this design could increase the performance of silicon batteries up to approximately 20%.

If so, this may be the key to realizing the promise of perovskite's solar industry - a series of compounds that have the same crystal structure and are made up of common elements like lead. , bromine and chlorine.

"This is one of the most interesting results I have witnessed for a long time , " said Michael McGehee, a perovskite expert at Stanford University in Palo Alto, California. "The increase in power generation efficiency they have declared is extremely impressive."

Perovskite is easily rolled into powerful optical absorption plates.

Silicon becomes the dominant material in the solar industry not only because they are the most optimal photovoltaic converters, but also because of their convenience and relatively cheap cost. However, this material requires manufacturers to use expensive specialized rooms to refine and prepare pre-production.

In contrast, perovskite is easily rolled into powerful optical absorption plates . Most materials carrying perovskite structures only absorb the photonic photons in their optimal way, so they need to be combined with other materials to absorb all other light-colored photons in the spectrum.

The solar industry is in the midst of commercializing solar cells from perovskite materials by installing them on top of conventional silicon modules, which are unable to absorb energy from photons. blue beams of light that convert these photons into heat instead of generating electricity. But in addition to the cost of adding equipment classes, manufacturers have also struggled with practical challenges such as creating a perfect parallel design so that the amount of electricity emitted from each battery is together. Otherwise, the overall line is limited by a weaker battery in the two plates.

Two years ago, researchers led by electrical engineer Hongwei Song at Jilin University in Changchun, China, reported on a solution to these challenges. By adding a small amount of rare metal ytterbium to a cesium and lead perovskite sample, they found that it is possible to form a perovskite structure parallel to a different and simpler architecture.

Like conventional perovskites, the doped version of ytterbium absorbs blue photons, energizing electrons in the material. But these electrons do not form electricity. Instead, they immediately transmit their energy to ytterbium atoms, which then re-emit almost all photons absorbed in the form of near-infrared light. Most of these photons compress into the silicon battery layer below, where all their energy is absorbed and converted into electricity with very little heat generated.

"With the task of converting solar energy into electricity, the combination of these materials is almost all you need," said Daniel Gamelin, a chemist at Washington University in Seattle.

However, the perovskites that Song's team created are nanoparticles, which are hard to assemble synchronously on a silicon battery. This is still a problem with the best commercially available solar cell products, in which silicon panels are coated on the surface of a protective glass layer intentionally roughened. Tiny glass tips help guide light into the battery layer instead of being reflected off its upper surface, but perovskite nanoparticles do not always form a seamless coating on the surface. rough.

At the meeting of the American Chemical Society last week here, Gamelin announced that he and his colleagues had found a solution to this problem. They used a fairly common solar cell manufacturing technique called vacuum deposition technique to create thin ytterbium phase perovskite layers stretching across silicon solar panels about 14 cm in length. This technique uses a layer of perovskite film to encase tiny glass tips on the surface of the battery.

'Experimental results from a parallel solar cell structure show that nearly all of the green light absorbed by perovskite is converted to photons near IR " , Gamelin presented in the report.

From this result, he predicted, covering a high-grade silicon battery of perovskite with ytterbium would allow it to successfully convert 32.2% of the solar energy absorbed into electricity, rising from the 27% previously - that is, an increase of 19.2%. Gaminin's team is currently doing experiments to verify those predictions.

"I'm a little skeptical about numbers," McGehee said. But even if it is only part of this increase, it will "be a great step forward" for humankind, he added.

Last month, Gamelin and colleagues launched a startup called BlueDot to commercialize the technology platform. They had a lot of competitors. Perovskite start-up companies like Oxford PV in the UK and Saule Technologies in Warsaw have completed testing their batteries with parallel silicon perovskite-silicon structures or are preparing to do so aggressively.

However, BlueDot still hopes to surpass other companies, because a simpler parallel design will allow manufacturers of solar cells from standard perovskite silicon to integrate into their production lines. easier - and in the future it will be possible to put perovskite on every roof all over the world.