According to researchers from A U of T Engineering innovation, creating solar cells can be as easy and inexpensive as printing a newspaper.
“Economies of scale have greatly reduced the cost of silicon manufacturing,” says University Professor Ted Sargent (ECE), an expert in emerging solar technologies and the Canada Research Chair in Nanotechnology and senior author on the paper.
Hairen Tan and his colleagues said they may have found the key to creating low cost printable solar panels (c) utoronto.ca
A new class of solar devices called perovskite solar cells could be the alternative solar technology to make low-cost, printable solar panels capable of turning nearly any surface into a power generator.
“Perovskite solar cells can enable us to use techniques already established in the printing industry to produce solar cells at very low cost. Potentially, perovskites and silicon cells can be married to improve efficiency further, but only with advances in low-temperature processes,” Sargent added.
Perovskite solar cells depend on a layer of tiny crystals. Each cells is about 1,000 times smaller than the width of a human hair, made of low-cost, light-sensitive materials. The perovskite's raw materials can be mixed into a liquid to form a kind of ‘solar ink’, they could be printed onto glass, plastic or other materials using a simple inkjet process.
However, most scientists still face a conundrum with the technology. In order to generate electricity, electrons excited by solar energy must be extracted from the crystals so they can flow through a circuit.
The extraction happens in a special layer called the electron-selective layer, or ESL. However, it's a challenge to manufacture a good ESL, which holds back the development of perovskite solar cell devices.
New perovskite solar cells have achieved an efficiency of 20.1 per cent and can be manufactured at low temperatures (c) utoronto.ca
“The most effective materials for making ESLs start as a powder and have to be baked at high temperatures, above 500 degrees Celsius,” says Tan in statement
. “You can’t put that on top of a sheet of flexible plastic or on a fully fabricated silicon cell — it will just melt.”
Thus, Tan's team developed a new chemical reaction than enables them to grow an ESL made of nanoparticles in solution, directly on top of the electrode. The process always stays below 150 degrees C, though heat is still required.
In a study published in Science, the scientists reported the success of the ongoing development of the technology, which they say is currently at 20.1 per cent.
“This is the best ever reported for low-temperature processing techniques,” says Tan. He adds that perovskite solar cells using the older, high-temperature method are only marginally better at 22.1 per cent, and even the best silicon solar cells can only reach 26.3 per cent.
“With our low-temperature process, we could coat our perovskite cells directly on top of silicon without damaging the underlying material,” says Tan. “If a hybrid perovskite-silicon cell can push the efficiency up to 30 per cent or higher, it makes solar power a much better economic proposition.”
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