Making every photon count

We have shown how a class of materials known as quasi-random structures based on binary gratings, makes it easy to tailor these structures towards specific applications, with the potential to transform the efficiency of next generation solar cells. This is a significant breakthrough, since it was widely considered all but impossible to develop such quasi-crystalline and random structures to specific applications.

CEEM has used these quasi-random structures to fabricate thin films that are so efficient at trapping broad-band light that they are approaching the theoretical limit of performance: a key issue for the photovoltaics that are at the heart of the solar energy market.

Our researchers have designed and demonstrated bespoke gratings placed on the surface of silicon thin films to ensure that light is only diffracted into specific angles thereby coupling to high-absorption modes. This arrangement significantly enhances the performance of thin film solar cells. Our team performed the modelling, design, measurement and fabrication of the materials to ensure best results.

By improving the energy efficiency of thin film materials, CEEM’s work has significant implications for Building Integrated Photovoltaics (BIPV)). This clean technology is increasingly being incorporated into the construction of new buildings as a source of electrical power.

“BIPV is one of the fastest growing segments of the photovoltaic industry, because someone else pays for the frames and the mechanical support” says CEEM’s Professor Thomas Krauss, whose breakthrough facilitates both the development of thinner films and improved electrical performance. “The absorption enhancement that we have demonstrated with our specially designed grating is of great interest to the BIPV market.”

CEEM is also looking at how more conventional silicon based solar panels can be enhanced and incorporated into BIPV. This ‘tandem approach’ to light management uses the same grating to control where the light gets absorbed and is also attracting industry interest.

Beyond solar, the management of photons could increase the performance of sensing and imaging technology in analytical chemistry and molecular biology, as well as in optical communications.

CEEM’s ability to carry out this path-finding research is built on three complementary qualities:

- World leading expertise in predictive modelling
- Facilities to fabricate materials and interfaces both at the atomic and the device level, using modelling to refine and improve their properties
- Unrivalled experimental analysis using bespoke electron microscopy.