Color blind glasses

Photonic glasses give solar panels pleasing colors

According to ACS Nano’s “High-Efficiency, Mass-Producible, and Colored Solar Photovoltaics Enabled by Self-Assembled Photonic Glass”, solar panels are no longer just for rooftops – some buildings even have these power-generating structures on all their roofs. facades.

But as more and more buildings and public spaces incorporate photovoltaic technologies, their monotonous black color could leave onlookers disappointed. Now researchers working in ACS Nano have created solar panels that take on colorful hues while producing power almost as efficiently as traditional panels.

Solar panels are usually deep black because their job is to absorb light, whereas a red car looks red because the finish reflects red light instead of absorbing it. Most attempts to color these devices will therefore reduce their ability to absorb light and generate energy.

An alternative is to use structural sources of color that take advantage of microscopic shapes to reflect only a very narrow and selective part of the light, such as the scales of butterfly wings. However, previous technologies attempting to incorporate structural color gave panels unwanted iridescence or were expensive to implement on a large scale.

So Tao Ma, Ruzhu Wang and their colleagues wanted to develop a way to color solar panels using a structural material that would be easy and inexpensive to apply, and maintain their ability to produce energy efficiently.

The team sprayed a thin layer of a material called photonic glass onto the surfaces of the solar cells. The glass consisted of a thin, disordered layer of microscopic dielectric spheres of zinc sulfide. Although most of the light could pass through the photonic glass, selective colors were reflected depending on the size of the spheres.

Using this approach, the researchers created solar panels that took on blue, green, and purple hues while only dropping power generation efficiency from 22.6% to 21.5%. They also found that solar panels made with this layer of photonic glass retained their color and performance in standard durability tests, and that manufacturing could be scaled up.

Researchers plan to explore ways to make colors more saturated, as well as methods to achieve a wider color gamut.

The authors acknowledge funding from the National Natural Science Foundation of China.