Researchers from Queen Mary University and Imperial College London have created a novel solar cell with a discerning music taste. Amazingly, the device produces up to 50 per cent more power when exposed to loud pop or rock music. Unfortunately for fans of Mozart and Bach, classical does not seem to elicit the same response, leading researchers to the conclusion that the wide range of frequencies present in the former genres are more favourable for enhancing the amount of electricity produced.

The solar cells’ party attitude can be explained by the piezoelectric effect, where vibrations in a material can produce an electric field. Traditionally, solar panels have been made from bulk semiconducting crystals like silicon. These work by
absorbing light energy from the sun and converting it into electricity by generating free electrons within the material. This is known as the photovoltaic effect. These new solar cells are made from tiny strands of zinc oxide called nanowires that are layered onto a polymer surface. The nanowires act as miniature antennae that pick up vibrations and use this energy to shake loose more electrons within the cell, in addition to the photovoltaic effect.

Polymer-nanowire solar cells could have many niche applications where there are high ambient sound levels or other external vibrations, such as near roadsides and airports and even at music festivals. They only require a sound level of 75 dB to work – equivalent to standing next to somebody singing. Currently, a drawback of polymer solar cells is their low efficiency – the electricity produced for each unit of sunlight received. For example, the efficiency of the sound enhanced nanowire-polymer solar cell was reported to be 1.8 per cent compared to well over 20 per cent for state of the art silicon devices. However, polymer solar cells have much lower material costs than the extremely pure silicon feedstock required for commercial-grade solar panels and have other advantages like being lighter, bendable and potentially less damaging to the environment. With further research and economies of scale, there is a big opportunity for plastics to be the solar panels of the future.

Chris Smith