Brightening up our future with perovskite —
The energy needs of the world could all, in principle, be fulfilled by one single source -- the sun. There are challenges in making this a reality, however: affordability first, and finding a way to capture this energy efficiently to turn it into electricity.Recently, a new material known as perovskite has seen the light of day and within just a few years it has started rivaling the efficiency of traditional photovoltaic solar cells, which currently maxes out at roughly 20 percent. This is the amount of solar energy that gets converted into electricity and the higher this is, the more we meet our energy needs. Over 80 percent of today's photovoltaics are made from crystalline silicon, but the high expense of both their production and installation means we are in need of alternatives.
Perovskite is a mineral found in the Earth's mantle, named after Russian mineralogist Lev Perovski. Since 2009, it has caught the attention of researchers across the globe, including those at Oxford University and the Federal Institute of Technology in Lausanne (EPFL).
"In a very short time, perovskite has begun to produce extremely high efficiencies and there's 'perovskite fever' going on," says Michael Graetzel, Director of the Laboratory of Photonics and Interfaces at EPFL. "Today, efficiency has peaked at 18 percent, but it's expected to get even higher in the future.
Graetzel discovered how perovskite works and he's helping develop new solar cells as well as potential ways to add on to existing ones: "You can put perovskite on top of traditional silicon cells to make them more efficient," he says. "This is not an expensive process and can become an attractive application for mainstream solar panels."
Stability tests are still needed as this magical material is sensitive to water and high temperatures: "This is all being examined now. I'm optimistic and sure this can be tackled. It's an exciting time."
Perovskite solar cells may be the ones to watch, but the search for the most efficient, affordable and usable form of solar energy is a diverse battlefield.
By Meera Senthilingam, for CNN
Brightening up our future with perovskite —
The new color of clean energyOxford Photovoltaics, a spin-out from the University of Oxford, are using perovskite to develop colored and semi-transparent glass which works as a solar cell and could then be integrated into the facades of buildings and windows.
Brightening up our future with perovskite —
Solar cells that keep their coolSolar cells can easily reach temperatures as high as 55 degrees Celsius when the sun's rays beat down on them. These racing temperatures not only reduce their efficiency when converting the sun's energy into electricity but also lower their lifespan.
Shanhui Fan and his team at Stanford University have developed a layer of silica glass which is specially patterned to deflect unwanted heat radiation when added onto the surface of regular solar cells.
Miniscule pyramid and cone-shaped structures are embedded into the glass and redirect any infrared radiation which causes heat, preventing the solar cells from heating up. But visible light rays can still pass through to generate electricity.
The team are creating prototypes and experimenting their efficiency with hopes of demonstrating them outdoors soon.
Brightening up our future with perovskite —
New solar panels from old car batteriesOld car batteries are being converted into long-lasting solar panels by researchers at MIT. The new applications are riding the current wave of popularity with perovskite-based solar cells.
Original designs for perovskite technologies use lead as part of their overall design. But this use of lead means toxic residues are leftover from its extraction from ores.
Angela Belcher and her team at MIT used recycled lead from car batteries as an alternative source of lead and as the perovskite materials are just micrometres thick, the amount of lead needed is minimal. Lead from a single car battery could produce enough solar panels to provide power for 30 households.
According to the Battery council international, more than 98% of all battery lead is currently recycled, mainly into new batteries. As cars change and demand declines for new batteries, increasing demand for perovskite panels could provide a new primary outlet and further enhance the green stamp on the technology.
Brightening up our future with perovskite —
Panels that never lose their focusThe high-cost and low efficiency of solar cells could partly be overcome with new designs by Glint Photonics which focus and capture more incoming sunlight to generate electricity.
Their self-tracking solar concentrators can change their reflectivity depending on the direction of incoming sunlight. As the sun moves and the direction its rays come in from also change, the concentrators track this movement and remove reflectivity in just that region of their surface, enabling the light to be enter and become concentrated and trapped to reach a solar cell.
Focusing light onto regular solar cells is usually conducted with specially constructed and placed mirrors and lenses which need to be constantly moved as the sun rises and descends across the sky. Removing their need and increasing the amount of sunlight captured could dramatically reduce the cost of solar power.
The design is currently a proof-of-concept and the team are working on improving efficiency further.
Brightening up our future with perovskite —
Solar power with a viewA new solar concentrator has been developed which can be placed over windows to create solar energy -- without obstructing your view. The most efficient solar cells to date are often colored to absorb the sun's rays more efficiently, but if made transparent they could become a lot more versatile.
The transparent device is being developed by Richard Lunt's team at Michigan State University and can be placed on anything with a clear surface, ranging from the facade of a building to a computer screen.
The solar harvesting system uses small organic molecules which absorb specific non-visible wavelengths of sunlight such as ultraviolet and near infrared. These in turn are made to 'glow' at another wavelength in the non-visible infrared which is guided to photovoltaics on the edges for conversion into electricity, whilst maintaining transparency.
The technology is at an early stage and very little energy is currently converted into electricity, but it has the potential to be scaled to commercial or industrial applications.
