Scientists Propose Technology That Could Reduce the Cost of High-Efficiency Solar Cells

A3B5 semiconductor material can be grown on an inexpensive silicon substrate and can decrease the price of multi-junction solar cells

February 25, 2020


The scientists of St. Petersburg University in Russia have tested a new technology for the fabrication of high-efficiency solar cells based on A3B5 semiconductors integrated on a silicon substrate.

A3B5 compounds are almost equivalent of Silicon (Si) and Germanium (Ge) by their elector-physical properties. This A3B5 semiconductor materials including gallium arsenide (GaAs), indium arsenide (InAs), gallium phosphide (GaP), indium phosphide (InP), gallium antimonide (GaSb), and indium antimonide (InSb), are used in manufacturing electronic and optoelectronic applications.

The scientists say that if this technology is used, it may increase the efficiency of the existing single-junction photovoltaic converters by 1.5 times. They have shown that A3B5 structures can be grown on an inexpensive silicon substrate, providing a decrease in the price of multi-junction solar cells.

“Such solar cells will be significantly more effective at absorbing sunlight and generating electricity,” added the University statement.

“We’ve learned to grow the topmost layer. This material system can potentially also be used for intermediate layers. If you add arsenic, you obtain quaternary GaPNAs alloy, and from it, several junctions operating in different parts of the solar spectrum can be grown on a silicon substrate,” said Ivan Mukhin, an ITMO University researcher.

According to him, the potential efficiency of such solar cells can exceed 40% under light concentration, which is 1.5 times higher than that of modern Si technologies.

With the rapid exhaustion of hydrocarbon fuel reserves and environmental issues, scientists are increasingly researching the development of green technologies, which also includes the development of solar technologies.

“Hydrocarbons as a traditional source of energy are exhaustible, and their burning leads to the production of carbon dioxide,” added Mukhin.

Sun can be a virtually inexhaustible energy source for the planet. According to the recent calculations, only 1% of the solar energy that reaches the earth daily would be enough to provide humans with enough electricity for a year.

“This is why in the future, solar energy has a chance to replace traditional energy sources that depend on burning fossil fuels,” said Mukhin.

Meanwhile, the team of researchers has revealed several factors that hinder the broader use of solar panels. For instance, conventional silicon solar cells have a relatively low efficiency – less than 20%. More efficient technologies require more complex semiconductor technologies, which significantly increases the price of the solar cells, the report suggests.

The most common solar cell technologies are silicon-based. According to Mukhin, “This is a relatively cheap and widespread material. The problem is that silicon is an indirect semiconductor and absorbs light rather poorly, which limits its use in efficient solar cells. There are other semiconductor materials, such as A3B5 semiconductor compounds, which consist of elements of the third and fifth groups of the Periodic Table. They are much better at absorbing light but are much more expensive than silicon, which significantly increases the cost of the resulting solar cells. As a result, despite their high efficiency, it’s not profitable to produce them.”

In November 2019, Beijing-based Hanergy Holding Group Ltd announced that its Chengdu Research and Development Center again breached the world record for its silicon heterojunction (SHJ) technology with a record-setting 25.11% conversion efficiency.

Earlier, it was reported by Mercom that by combining thin-film solar modules based on perovskite semiconductors with semiconductors made of copper, indium, gallium, and selenium, solar module technology could cross the 30% efficiency mark.

Image credit: ITMO


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