New measurement and data analysis techniques, its crystal structure defects insight into the performance of the robbery, and ultimately improve the performance of solar cells.
While solar cells made from light-harvesting perovskite (an organic-inorganic hybrid) materials have recently eclipsed the 20 percent efficiency mark, researchers believe they could do better if they had a clearer picture of energy flow at the nanometer scale. The ORNL discovery, described in a paper published in ACS Photonics, synchronizes microscopy, ultra-short pulses of laser light and data analytics to extract images with single-pixel precision, providing unprecedented detail.
"If we can see exactly and in real time what is happening, we can map out the electronic processes in space instead of relying on snapshots gleaned from spatial averages," said Benjamin Doughty, one of the authors and a member of ORNL's Chemical Sciences Division.
Armed with information about what electrons are doing inside the material, researchers believe they can make improvements that lead to solar cells that are more efficient and potentially less expensive.
"With conventional approaches of studying photovoltaic materials, we are unable to accurately map out electronic processes and how electrons are getting lost," Doughty said. "Those processes can translate into losses in efficiency."
The experiment consists of optically pumping the thin film sample with a 50 femtosecond -- or 50 millionths of a billionth of a second -- laser pulse and then measuring changes in light absorption with a second laser pulse in the material. The technique, called femtosecond transient absorption microscopy, consists of a tabletop of lasers, optics and a microscope. The net result is a pixel-by-pixel map of the material being studied and information researchers can use to improve performance.
"The ability to identify what will be created after the solar cell absorbs a photon, either a pair of free charges or their bound form called an exciton, is crucial from both fundamental and applied perspectives," said co-author Yingzhong Ma, who led the research team. "We found that both free charges and excitons are present, and the strength of our approach lies in not only identifying where they are but also determining what their relative contributions are when they are both present at a given spatial location."
The key challenge is how to understand the rest of the space differences observed whether happen because Ma said he and his colleagues are possible, they are at the bottom of the dynamic structure information and associated electronics to try to find an all-optical imaging methods. This approach allows you to understand, with the help of researchers and maps related to the perovskite and water degradation. Ma, you can succeed on the basis of such materials, prior to the solar cell, it was noted that the issue must be resolved.Tag:   solar power plant solar power system solar power solar energy solar power bank