New discoveries made concerning an appealing solar cell product, thanks to new microscope

• A group of researchers from the Department of Energy's Ames National Laboratory has created a new characterization tool that permitted them to gain unique understanding into a possible alternative material for solar cells.

Under the leadership of Jigang Wang, senior scientist from Ames Lab, the team created a microscope that uses terahertz waves to collect information on material samples. The group after that used their microscope to check out methylammonium lead iodide (MAPbI3) perovskite, a material that can potentially change silicon in solar cells.

Richard Kim, a researcher from Ames Lab, explained both attributes that make the new scanning probe microscope unique. First, the microscope uses the terahertz variety of electromagnetic frequencies to collect information on materials. This variety is much below the visible light spectrum, dropping between the infrared and also microwave frequencies. Secondly, the terahertz light is radiated with a sharp metal tip that boosts the microscope's capabilities towards nanometer length scales.

" Typically if you have a light wave, you can not see points smaller sized than the wavelength of the light you're using. And also for this terahertz light, the wavelength has to do with a millimeter, so it's quite big," explained Kim. "However right here we used this sharp metallic pointer with an apex that is sharpened to a 20-nanometer distance curvature, and also this functions as our antenna to see points smaller than the wavelength that we were making use of."

Using this new microscope, the group checked out a perovskite material, MAPbI3, that has actually lately become of interest to researchers as an alternative to silicon in solar cells. Perovskites are an unique sort of semiconductor that moves an electrical charge when it is exposed to visible light. The main obstacle to utilizing MAPbI3 in solar cells is that it degrades conveniently when exposed to elements like heat as well as moisture.

According to Wang and Kim, the group expected MAPbI3 to act like an insulator when they subjected it to the terahertz light. Because the data collected on an example is a reading of just how the light scatters when the material is exposed to the terahertz waves, they expected a constant low-level of light-scatter throughout the product. What they discovered, however, was that there was a great deal of variant in light scattering along the boundary between the grains.

Kim explained that conductive materials, like metals, would certainly have a high level of light spreading, while less conductive materials like insulators would not have as much. The broad variant of light scattering found along the grain limits in MAPbI3 sheds light on the material's destruction problem.

Throughout a week, the team remained to collect information on the material, as well as information collected because time showed the degradation procedure through adjustments in the levels of light scatterings. This info can be helpful for enhancing and also controling the material in the future.

" Our team believe that the here and now study demonstrates a powerful microscopy tool to picture, understand as well as potentially alleviate grain boundary deterioration, defect traps, and also materials deterioration," stated Wang. "Far better understanding of these issues may make it possible for establishing very reliable perovskite-based photovoltaic or pv tools for several years ahead."

The samples of MAPbI3 were offered by the University of Toledo. This study is more gone over in the paper "Terahertz Nanoimaging of Perovskite Solar Cell Products," written by Richard H. J. Kim, Zhaoyu Liu, Chuankun Huang, Joong-Mok Park, Samuel J. Haeuser, Zhaoning Song, Yanfa Yan, Yongxin Yao, Liang Luo, and also Jigang Wang, and also released in the ACS Photonics.