Vibrations from pop music boost solar-cell performance

Scientists at the Queen Mary University of London and Imperial College London have found that vibrations, like those caused by pop and rock music, improve the performance of solar cells. Their study has been published in the journal Advanced Materials.

Dr Steve Dunn, Reader in Nanoscale Materials from Queen Mary’s School of Engineering and Materials Science, and his team grew billions of nanorods made from zinc oxide, then covered them with an active polymer to form a nanogenerator - a device that converts sunlight into electricity. Dr Dunn’s research assistant, Dr Joe Briscol, noted, “The whole device was extremely simple and inexpensive to produce as the zinc oxide was grown using a simple chemical solution technique and the polymer was also deposited from a solution.”

Using the properties of the zinc oxide material, the team found that sound levels as low as 75 decibels (equivalent to a typical roadside noise or a printer in an office) could significantly improve the solar cell performance. Scientists had previously shown that applying pressure or strain to zinc oxide materials could result in voltage outputs, known as the piezoelectric effect, but the effect of piezoelectric voltages on solar-cell efficiency had not received significant attention before.

“We thought the soundwaves, which produce random fluctuations, would cancel each other out and so didn’t expect to see any significant overall effect on the power output,” said James Durrant, Professor of Photochemistry at Imperial College London, who co-led the study.

“The key for us was not only that the random fluctuations from the sound didn’t cancel each other out, but also that some frequencies of sound seemed really to amplify the solar cell output - so that the increase in power was a remarkably big effect considering how little sound energy we put in.”

Professor Durrant said the team tried playing various types of music in order to explore the effect of different pitches, and they found the solar cells “respond best to the higher pitched sounds present in pop music”. In fact, the high frequencies and pitch found in pop and rock music caused vibrations that led to a 40% increase in solar-cell efficiency.

The study has implications for improving energy generation from sunlight, particularly for the development of new, lower-cost, printed solar cells. Dr Dunn said if the technology could be moved to bigger devices, it could be used to power items that are exposed to acoustic vibrations, such as air-conditioning units, video screens in trains or taking off the alternator load in cars.

He added that the team is currently working on the technology with the National Physical Laboratory, “who are helping us with the measuring and the calibration and the traceability of our output from our devices”.

“I think we’re probably just at the start of a journey,” he said, “and what we’re looking to do is take that as far down the avenue as we can go.”

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