Researchers have developed a 1μm (micrometre) thick solar cell capable of converting 66.5% of sunlight into electricity.

A scientific paper published in the ACS Photonics journal details a silicon cell generating 26.3mA/cm² (milliampere per square centimetre) under test conditions. This marks a 25% increase on the previous ultra-thin solar record of 19.72 mA/cm² achieved in 2017.

The developers estimate that the cells, approximately 100 times thinner than a sheet of international standard paper, could further improve to 33.8mA/cm². This would create a photovoltaic cell with 21% efficiency, roughly in line with larger panels.

The developed ultra-thin solar cells build on previously developed ultra-thin crystalline structures, instead using “correlated disordered hyperuniform patterns”. These allow more than double the solar light absorption of a uniform slab of silicon.

Academics from the UK’s University of Surrey and Imperial College London collaborated with researchers from the Centre for Nanophotonics and the Advanced Research Centre for Nanolithography, both in the Netherlands, to develop the cell.

The team manufactured the test cells using ultra-thin silicon crystals, ‘engraving’ these with patterns using electron beam lithography and etching fluids. The end product had a slightly varying thickness of approximately 1.18μm across areas of 1.3×1.3 mm² or 4.8×4.8 mm².

The developers say they will now investigate commercial partnering and possible manufacturing techniques.

Dr Marian Florescu, from the University of Surrey’s ADVANCED TECHNOLOGY INSTITUTE , said: “One of the challenges of working with silicon is that nearly a third of light bounces straight off it without being absorbed and the energy harnessed. A textured layer across the silicon helps tackle this and our disordered, yet hyperuniform, honeycomb design is particularly successful.

“There’s enormous potential for using ultra-thin photovoltaic solar. For example, given how light they are, they will be particularly useful in space and could make new extra-terrestrial projects viable. Since they use so much less silicon, we are hoping there will be cost savings here on Earth as well, plus there could be potential to bring more benefits from the internet of things and to create zero-energy buildings powered locally.”