Electricity-Generating Transparent Solar Cells Developed

A newly developed transparent polymer solar cell (PSC) capable of generating electricity could bring us a step closer to a future in which windows in buildings and homes generate electricity from the sun without blocking the view outside.

PSCs have attracted widespread attention because they are more lightweight and flexible than competing solar cell technologies, and they can be produced in high volume at low cost. Scientists have been investigating PSCs for their potential in making unique advances for broader applications, such as building-integrated photovoltaics (PV) and integrated PV chargers for portable electronics.

Previous attempts toward demonstrating visibly transparent or semitransparent PSCs have resulted in low visible-light transparency and/or low device efficiency because suitable polymeric PV materials and efficient transparent conductors were not well deployed in device design and fabrication.

(Image: UCLA)

To correct these shortcomings, scientists at the University of California, Los Angeles, have developed a solar cell made from a photoactive plastic that is nearly 70 percent transparent to the human eye. Rather than generating electricity from visible light, their PSC works with infrared light.

“These results open the potential for visibly transparent polymer solar cells as add-on components of portable electronics, smart windows and building-integrated photovoltaics and in other applications,” said study leader Yang Yang, a UCLA professor of materials science and engineering and director of the Nano Renewable Energy Center at California NanoSystems Institute.

The team developed the PSCs by incorporating near-infrared light-sensitive polymer with silver nanowire composite films. These films were used as the top transparent electrode. The near-infrared photoactive polymer absorbs more near-infrared light but is less sensitive to visible light, balancing solar cell performance and transparency in the visible-wavelength region.

In previous attempts, opaque metal electrodes were used as conductors. Now, the UCLA team used a combination of silver nanowire and titanium dioxide nanoparticles to produce the electrode. They fabricated the solar cells at a reduced cost through solution processing, and they achieved a power conversion efficiency of 4 percent.

The study — supported by the Henry Samueli School of Engineering and Applied Science, the Office of Naval Research and the Kavli Foundation — appeared in ACS Nano.

For more information, visit: www.ucla.edu