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Semiconductor silicon wafers: What new hope can solar photovoltaic power generation bring?
- Apr 28, 2018 -

Semiconductor silicon wafers: What new hope can solar photovoltaic power generation bring?

One is a wafer of semiconductor materials, and the other is solar photovoltaic power generation. There seems to be no connection between the two fields, but when they are combined, new hopes arise. Recently, a study by Purdue University in the United States proved this point.

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Semiconductor silicon wafers: What new hope can solar photovoltaic power generation bring?

Related background

Speaking of "wafers," people in the semiconductor industry will not be unfamiliar. It refers to the silicon wafers used in silicon semiconductor integrated circuit manufacturing. Because of their circular shape, they are called wafers. The silicon semiconductor integrated circuit manufacturing process has always been inseparable from this basic material. A variety of integrated circuit components are also manufactured by it.

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Semiconductor silicon wafers: What new hope can solar photovoltaic power generation bring?

Innovation and exploration

However, what we want to introduce today is not the improvement of the wafer process, and it is not even related to integrated circuits. To our surprise, researchers through innovative explorations applied wafers as a material to the field of solar power generation, and brought us unexpected new effects.

They use silicon wafers that have been widely commercialized, modify their structure, make it more effective in absorbing solar energy, and are resistant to high temperatures to meet the needs of the "concentrated solar" power plant operating 24 hours a day.

The details of this invention were published in the April 3 issue of Applied Physics Letters.

Key technologies

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Semiconductor silicon wafers: What new hope can solar photovoltaic power generation bring?

Selectively absorb light

"Concentrated solar" power generation systems typically use mirrors to collect sunlight on "selective solar absorbers and reflectors" to collect and store energy. In order to collect solar energy more effectively, researchers have specially designed this low-cost surface material that can selectively absorb light in a specific spectral range and reflect other parts.

Prevent re-radiation

Peter Bermel, assistant professor at the School of Electrical and Computer Engineering at Purdue University, said: "The key point of this study is that in order to collect sunlight as efficiently as possible, you must do two things that compete with each other: one is to absorb from the sun. As much energy as possible, and the other is not radiating energy again. If you make something hot, it will start to glow red, and we are trying to prevent it from happening when absorbing sunlight. Secondary radiation."

This silicon solar device contains an anti-reflection layer coated with silicon nitride on the upper layer and a back-emission layer made of silver, which can effectively reduce re-radiation.

In response, Peter Bermel said:

“In the research, we used ready-made silicon wafers as a design and manufacturing platform to make a structure that can absorb a lot of sunlight without re-radiating much calories out. We added one at the top and one at the bottom. The layer enhances its ability to absorb light while also reflecting longer wavelengths."

Stable performance at high temperatures

After the research team modified the silicon wafer, it could withstand high temperatures near 535 degrees Celsius without affecting stability or performance. In this regard, graduate student Hao Tian said: “We have demonstrated through experiments that selective solar absorbers can maintain high efficiency at high temperatures. This structure is easy to manufacture and stable under the high temperature conditions of “concentrated solar” applications. ."

Improve energy conversion efficiency

For energy conversion rate, graduate student Zhiguang Zhou said:

“This work demonstrates that efficient solar thermal conversion can be accomplished with very simple structures and common materials. This is a key step for practical applications and we hope it will continue along this path.”

Flexibility

Through this silicon wafer structure, researchers have explored selective absorbers made of silicon thin films. The flexibility of the thin film brings with it more potential advantages. For example, it can be applied to curved structures such as concentrating solar power systems. Used as a mirror-like trough parabola. This "groove parabola" can track the sun throughout the day, concentrating solar energy by about 50 times.

Bermel said:

“These films not only perform really well, but they are so soft that you can cover it on any surface.”

Key challenges

The complexity of the research is that the properties of the material change dynamically when the temperature rises from room temperature to around 500 degrees Celsius.

In response, the research team expanded their previous research in this field and developed a sophisticated model that can simulate changes in material properties at elevated temperatures.

Research value

This research aims to advance the world's research on hybrid energy systems, including solar photovoltaic cells, thermoelectric equipment, and steam turbines. Solar photovoltaic cells can convert visible light and ultraviolet light into electricity. Thermoelectric devices can convert heat into electricity. Steam turbines can use steam to generate electricity.

Ideally, this hybrid solar system efficiency exceeds 50%, and as a comparison, photovoltaic panels alone have only 31%. The researchers evaluated the sun's focus due to the "slotted paraboloid", which translates 51.5% of the light into usable high heat at 490 degrees Celsius.

Bermel said:

"The results of these studies make up for our previous deficiencies in the design of hybrid solar systems and represent its use as one of the key experimental components for this 24-hour solar power system."

Future applications

Future research includes research on "flexible thin film" solutions. The long-term goal is to integrate all components into a working system and continuously generate electricity. Such a system is expected to be used in large power stations or small residential systems in the future.