A U of T Engineering innovation could make printing cells as easy and inexpensive as printing a newspaper. Dr. Hairen Tan and his team have cleared a critical manufacturing hurdle in the development of a relatively new class of solar devices called perovskite solar cells. This alternative solar technology could lead to low-cost, printable solar panels capable of turning nearly any surface into a power generator.
“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. “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.”
Today, virtually all commercial solar cells are made from thin slices of crystalline silicon which must be processed to a very high purity. It’s an energy-intensive process, requiring temperatures higher than 1,000 degrees Celsius and large amounts of hazardous solvents.
In contrast, perovskite solar cells depend on a layer of tiny crystals — each about 1,000 times smaller than the width of a human hair — made of low-cost, light-sensitive materials. Because the perovskite 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.
But, until now, there’s been a catch: in order to generate electricity, electrons excited by solar energy must be extracted from the crystals so they can flow through a circuit. That extraction happens in a special layer called the electron-selective layer, or ESL. The difficulty of manufacturing a good ESL has been one of the key challenges holding back the development of perovskite solar cell devices.
“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. “You can’t put that on top of a sheet of flexible plastic or on a fully fabricated silicon cell — it will just melt.”
Tan and his colleagues developed a new chemical reaction than enables them to grow an ESL made of nanoparticles in solution, directly on top of the electrode. While heat is still required, the process always stays below 150 degrees C, much lower than the melting point of many plastics.
The new nanoparticles are coated with a layer of chlorine atoms, which helps them bind to the perovskite layer on top — this strong binding allows for efficient extraction of electrons. In a paper recently published in Science, Tan and his colleagues report the efficiency of solar cells made using the new method 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.
Another advantage is stability. Many perovskite solar cells experience a severe drop in performance after only a few hours, but Tan’s cells retained more than 90 per cent of their efficiency even after 500 hours of use. “I think our new technique paves the way toward solving this problem,” says Tan, who undertook this work as part of a Rubicon Fellowship.
“The Toronto team’s computational studies beautifully explain the role of the newly developed electron-selective layer. The work illustrates the rapidly-advancing contribution that computational materials science is making towards rational, next-generation energy devices,” said Professor Alán Aspuru-Guzik, an expert on computational materials science in the Department of Chemistry and Chemical Biology at Harvard University, who was not involved in the work.
“To augment the best silicon solar cells, next-generation thin-film technologies need to be process-compatible with a finished cell. This entails modest processing temperatures such as those in the Toronto group’s advance reported in Science,” said Professor Luping Yu of the University of Chicago’s Department of Chemistry. Yu is an expert on solution-processed solar cells and was not involved in the work.
Keeping cool during the manufacturing process opens up a world of possibilities for applications of perovskite solar cells, from smartphone covers that provide charging capabilities to solar-active tinted windows that offset building energy use. In the nearer term, Tan says his technology could be used in tandem with conventional solar cells.
“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.”
Learn more: Printable solar cells just got a little closer
Receive an email update when we add a new SOLAR CELLS article.
The Latest on: Solar cells
via Google News
The Latest on: Solar cells
- Green Solar Technologies Founder Pleased about New Technology to Reduce Dust on Solar Panelson December 12, 2019 at 4:07 pm
Nicki Zvik shares excitement about technology that could make solar panels easier to maintain. LOS ANGELES, Dec. 12, 2019 /PRNewswire-PRWeb/ -- With so much hype around the environmental and financial ...
- ‘Revolutionary’ solar panel company frozen by SEC in emergency actionon December 12, 2019 at 9:32 am
The revolutionary “Nanopanel” sounds like a world-changing invention to warm Greta Thunberg’s heart. Nanotech Engineering of Irvine, Calif. says its “last generation solar panel” is “a lightweight, ...
- Multi-bandgap Solar Energy Conversion via Combination of Microalgal Photosynthesis and Spectrally Selective Photovoltaic Cellon December 12, 2019 at 2:15 am
We use a fullerene-based organic photovoltaic cell with a high bandgap, which is best suited for the spectrum separation ... have great potential for improving the biomass productivity of microalgae ...
- Stretchable and colorless freestanding microwire arrays for transparent solar cells with flexibilityon December 12, 2019 at 1:35 am
Transparent solar cells (TSCs) are emerging as building blocks for building-integrated power generation 1,2,3,4. In this attractive concept of photovoltaics, there is an unavoidable trade-off between ...
- Fairfax County hopes solar panel deal saves on electric rateson December 11, 2019 at 6:53 pm
Fairfax County has contracted with energy providers to install solar panels on schools and other government properties at no cost to taxpayers — a move officials say will save $60 million in electric ...
- Q CELLS strengthens its presence in Southeast Asia with two social good solar projects in Thailandon December 11, 2019 at 6:19 pm
Q CELLS' Q.PEAK DUO L-G5 solar modules selected for 114 kWp rooftop installation at the Mae Fah Luang Foundation - Thailand's Royal Family-backed non-profit organization that assists the nation's ...
- AI-driven robots are making new materials, improving solar cells and other technologieson December 11, 2019 at 1:22 pm
He had asked her to refine a key material in solar cells to boost its electrical conductivity. But the number of potential tweaks was overwhelming, from spiking the recipe with traces of metals and ...
- Punching holes in solar cells turns them into transparent windowson December 11, 2019 at 8:30 am
Your office windows could soon be replaced with solar panels, as scientists have found an easy way to turn the green technology transparent. The trick is to punch tiny holes in them that are so close ...
- Punching holes in opaque solar cells turns them transparenton December 11, 2019 at 8:03 am
Researchers in Korea have found an effective and inexpensive strategy to transform solar cells from opaque to transparent. Existing transparent solar cells tend to have a reddish hue and lower ...
via Bing News