08 August 2012
An interdisciplinary group of researchers from the University of California Los Angeles (UCLA) in the US developed a high-performance polymer solar cell (PSC) that is highly transparent in the visible light range and produces energy by absorbing near-infrared and infrared radiation from the solar spectrum.
“Our breakthrough changes the concept of how and where solar cells can be used. It will help to expand the use of photovoltaics in daily life beyond roof top applications,” says Rui Zhu, PhD, postdoctoral member of the Research Group for Organic Electronic Materials and Devices in UCLA’s Yang Yang Laboratory.
UCLA’s novel PSC cell represents advances from existing transparent solar cells, which in terms of transparency and efficiency typically sacrifice one in favour of the other. These lightweight, flexible PSCs made from photoactive plastic-like materials are nearly 70% transparent to the human eye, because they mainly use near-infrared and infrared radiation. “At this stage, we only utlised 650 to 900 nanometers, and new materials will be able to utilise the deeper IR part [of the solar spectrum],” specifies study leader Professor Yang Yang, who also is director of the Nano Renewable Energy Center at the California NanoSystems Institute (CNSI), an integrated research facility located at UCLA and the UC Santa Barbara.
Eventually, the scientists want to achieve a power conversion efficiency goal of 10%. “Although the current performance is about 4%, these results open the potential for further improvement of the transparent solar cells,” says Zhu, who is also one of the corresponding authors of the paper “Visibly Transparent Polymer Solar Cells Produced by Solution Processing,“ which appeared in the journal ACS Nano. “We are working on developing the high performance active layer materials to further improve the device performance.” What’s more, the entire device can be processed through solution-based processes, which will make high-volume manufacturing significantly cheaper.
In fact, designing the top transparent electrode in compatibility with the bottom active layers was the biggest challenge in innovating this solar technology. “We utilised the silver nanowire-based composite as the transparent electrode to achieve the efficient electricity extraction from the active layer,” Zhu explains his team’s solution to the problem.
Written by Sandra Henderson, Research Editor, Solar Novus Today
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