Could sunlight enable our clothes to generate electricity?

Do you know what the sun does?

Sunlight can bring us light and warmth, help plants to photosynthesize, and kill germs...

Is there anything else? Of course there is! Sunlight can also generate electricity!

How can we generate electricity from sunlight?

This is where solar cells come in. As long as sunlight shines on this special device, it can convert the absorbed solar energy into electrical energy. Moreover, it is silent and does not produce pollutants when working, making it a very advanced, pollution-free green energy technology.

What does a solar cell look like?

If you observe carefully, you may see large, thin flat-panel devices composed of many small dark squares on some roofs, telephone poles or large open spaces. Those are solar cells.

At present, these solar cells are basically made of ultra-high purity crystalline silicon. Silicon is extracted from sand and is the most critical material in the "brain" (high-end chips) of mobile phones and computers.

In addition to being used on the ground, there are also many solar cells in space that provide a steady supply of electricity to satellites and space stations. These solar cells usually use a material called gallium arsenide. It is lighter than crystalline silicon and has a stronger ability to convert light into electricity. Our Tiangong space station uses gallium arsenide solar cells independently developed by my country, and it has reached the international leading level.

Speaking of this, do you also want to own a solar cell?

With this magical device, you don't have to worry about your phone or computer running out of power even if you're outdoors for a long time. Those who are performing special tasks in the wild can also charge their electronic devices at any time.

But who would be willing to carry a heavy and easily breakable "big guy" on their back during a happy journey?

Is it possible to invent a soft and thin solar cell that we can carry with us?

For example, clothes that can generate electricity, solar battery umbrellas...

This question was also asked to a scientist, Professor Zou Dechun from Peking University.

Zou Dechun is an expert in optoelectronic materials and devices in my country. He knows that making a heavy solar panel as thin and soft as a piece of clothing has always been just a dream, and it is also a problem that is recognized by the industry as impossible to solve. Do you want to challenge the world's problems?

want!

In order to meet the challenge, he conducted a lot of literature research and analyzed and summarized the reasons why previous challenges failed.

Suddenly one day, he thought: Why do we have to limit ourselves to transparent conductive plates like glass? If we can change the material to solve the problem of light absorption and conductivity, wouldn’t it be fine? In this way, a solar cell model with a new structure consisting of "dye sensitization + translucent screen" was born.

It is easier said than done. For the solar cell with a completely new structure that he envisioned, there was no ready-made processing equipment, no ready-made materials, no ready-made processing technology, and even no conductive fibers and meshes that met the technical requirements!

Then find a way! You can't imagine that the initial experimental materials for such high-tech solar cells were borrowed from the window screen factory.

Speaking of transparency, in addition to glass windows, aren’t there also partially transparent screens in our daily lives? Therefore, screens have become the best breakthrough point for verifying new technical ideas.

However, most manufacturers' screens did not meet the requirements. When he was at a loss, by chance, Zou Dechun found a high-end screen manufacturer on the Internet that could provide metal fiber and woven wire mesh that met the requirements.

At that time, people thought he needed it for renovation and needed it urgently, so they took a large truck into the city to deliver it. On a snowy evening, the two parties met on the roadside.

Next, the research team began to work with these "hard-earned" treasures. The scene in the laboratory at that time really looked like a processing workshop, so students passing by the laboratory often mistakenly called Zou Dechun "Master Zou".

Soon, a prototype of the solar cell made of ordinary metal mesh was developed, and they connected it to professional instruments for testing.

Ah, the indicator light is on!

Everyone was very happy! They had been researching the project for nearly two years, and it was successful for the first time! This "screen window experiment" proved that it is feasible to use metal wire as a solar cell substrate!

However, the current of this stainless steel mesh is too weak, and the material is not soft and tough enough to be used for solar cell clothing.

So Zou Dechun led the team to continue working hard!

After repeated research, they proposed for the first time in the world the new idea of ​​using flexible fibers to realize dual-electrode wound structure fiber solar cells.

Of course, having ideas alone is not enough, they also need to be tested in practice.

The technical challenge facing us is that to truly make a single flexible fiber solar cell that can be woven, it is necessary to accurately and accurately coat a layer of electric energy conversion material with a thickness of only one hundredth that of paper on a metal wire that is about the same thickness as a hair. This is exquisite carving in the microscopic world!

Faced with challenges, all they can do is find ways to improve the equipment and tackle the preparation process.

At such a critical moment, Zou Dechun fell ill. But the experiment could not be stopped! He had just finished the operation and could only lie on the hospital bed with 5 tubes inserted in his body, but he was still worried about his work...

Thanks to the joint efforts of everyone, the first batch of flexible fiber-structured solar cell samples were developed - a thin wire only a few centimeters long.

When the operator nervously connected several such thin wires and connected them to the small fan, the fan started to turn!

The team is excited!

When they published the experimental results, they received great attention and recognition from their peers around the world, which enabled my country to become a world leader in solar cell technology.

They continued their research and now the length of the fiber solar cell has exceeded 1 meter.

Looking back, Zou Dechun said: "Everything is possible only if people dare to think. But science is not just fantasy, science requires practical work. Only by doing can we achieve results."

Flexible fiber solar cells make it possible for people to dream of "using clothes to collect sunlight to generate electricity". However, many problems need to be solved before they can be used in large quantities in life, which will take a long time.

Source: Chongqing Industry-University-Research Cooperation Promotion Association

Author: Pan Fusheng, Academician of the Chinese Academy of Engineering, Professor of Chongqing University, Chairman of Chongqing Association for Science and Technology

Review expert: Mao Yi, chief expert of Chongqing Science Communication Expert Group, professor of Chongqing Electronic Engineering Vocational College

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