From Sound To Light — New Tandem Solar Cell Design Inspired By Buddhist Singing Bowls

Thanks to Dr. Niraj Lal of the Australian National University, we now know that small nano-sized versions of Buddhist singing bowls resonate with light in a similar way as they do with sound. Dr Niraj Lal found, while working on his Ph.D. at the University of Cambridge, that the shape is capable of working well with solar photovoltaic technology.

Centuries-old Buddhist singing bowls have a shape and talent that caught the Canberra scientist’s attention and sparked him to consider the bowl’s shape for solar cells to maximize efficiency. Applying this shape to solar cells, it increases their ability to capture more light and convert it into electricity.

Niraj Lal with a Buddhist bowl. Credit: OK-White Lane

Niall Byrne from Phys.org reports: “During his PhD, Niraj discovered that his ‘nanobowls’ manipulated light by creating a ‘plasmonic’ resonance, which quadrupled the laboratory solar cell’s efficiency compared to a similarly made flat solar cell.”

“Current standard solar panels lose a large amount of light-energy as it hits the surface, making the panels’ generation of electricity inefficient,” says Niraj. “But if the cells are singing bowl-shaped, then the light bounces around inside the cell for longer.”

Niraj and a team of research colleagues are going to try bringing his singing-bowl discovery to tandem solar cells, “a technology that has previously been limited to aerospace applications,” Phys.org notes.

Notably, this nicely follows one of our previous articles, by reader James Wimberley, Perovskite Solar Cells Beat New Records (In The Lab): “We are eagerly waiting for someone in the lively and fast-growing research community to announce a working tandem cell, perovskite on silicon, with a combined efficiency of 30%.” That’s what Niraj’s team claims it can hit, and that is compared to a laboratory efficiency of 25% for conventional solar panels (20% for commercial solar panels).

The Phys.org article gives a bit more explanation to the idea of tandem solar cells: “The tandem cell design works by absorbing a sunlight more effectively —each cell is made from a different material so that it can ‘see’ a different light wavelength.”

“To a silicon solar cell, a rainbow just looks like a big bit of red in the sky—they don’t ‘see’ the blue, green or UV light—they convert all light to electricity as if it was red ,” says Niraj. “But when we put a second cell on top, which ‘sees’ the blue part of light, but allows the red to pass through to the ‘red-seeing’ cell below, we can reach a combined efficiency of more than 30 percent.”

“Every extra percent in efficiency saves you thousands of dollars over the lifetime of the panel,” says Niraj. “Current roof-top solar panels have been steadily increasing in efficiency, which has been a big driver of the fourfold drop in the price for these panels over the last five years.”

Niraj hasn’t yet mentioned the potential use of perovskite, but we’ll see if he and his team decide to go with that. In reference to perovskite solar cells, James noted: “We’ve seen many promising solar technologies crash and burn. Why should this one be different? There is no guarantee of course, but perovskites have a lot going for them. The underlying materials are cheap. There’s no fundamental reason why efficiency can’t increase further.”

Buddhist singing bowls are in vogue these days with the natural healing and meditative crowds. They create what some consider a healing music with a continuous harmonic ringing sound. The rim of the metal bowl vibrates with the tap of a wooden utensil.

We hope that Niraj research is solid. It makes sense that something so useful for ages, such as the Buddhist singing bowl, will simply redefine its timeless usefulness.