May 8 2017
A team of researchers, led by the University of Minnesota, have discovered a new nano-scale thin film material with the highest-ever conductivity in its class. Credit: University of Minnesota
A new nano-scale thin film material has been discovered by a research team headed by the University of Minnesota. This new material, with the highest-ever conductivity in its class, is capable of leading to faster, smaller, and more powerful electronics besides developing more efficient solar cells.
The discovery was recently published in Nature Communications, an open access journal that features high-quality research from all areas of the natural sciences.
According to researchers, this material is considered to be unique due to its high conductivity, which allows electronics to conduct more electricity and become increasingly powerful. This material also a wide bandgap, highlighting that light can effortlessly travel through the material making it optically transparent. In several cases, materials with a wide bandgap, generally have either poor transparency or low conductivity.
The high conductivity and wide bandgap make this an ideal material for making optically transparent conducting films which could be used in a wide variety of electronic devices, including high-power electronics, electronic displays, touch screens and even solar cells in which light needs to pass through the device.
Professor Bharat Jalan, Chemical Engineering and Materials Science, University of Minnesota
Currently, a chemical element called indium is used by almost all the transparent conductors in electronics. Over the last two decades, the price of indium has generally increased, adding to the cost of current display technology. This has indeed resulted in a remarkable effort to find alternative materials that function as well, or even better, than indium-based transparent conductors.
Researchers discovered a solution in this study. They produced a new transparent conducting thin film with the help of a novel synthesis method, in which they grew a BaSnO3 thin film (a mixture of tin, barium and oxygen, called barium stannate), but replaced elemental tin source with a chemical precursor of tin. The chemical precursor of tin has novel, radical properties that greatly enhanced the metal oxide formation process besides improving the chemical reactivity. When compared to indium, both tin and barium are significantly cheaper and also abundantly available.
We were quite surprised at how well this unconventional approach worked the very first time we used the tin chemical precursor. It was a big risk, but it was quite a big breakthrough for us.
Abhinav Prakash, Graduate Student, Chemical Engineering and Materials Science, University of Minnesota
Jalan and Prakash stated that this new process allowed them to produce this material with extraordinary control over composition, thickness, and defect concentration. They pointed out that this process should be extremely perfect for a number of other material systems in which oxidizing the element is difficult. The new process is also scalable and reproducible.
They also stated that they succeeded in discovering the high conductivity in the material because of the structurally superior quality with enhanced defect concentration. These researchers will continue to focus on reducing the defects at the atomic scale.
Even though this material has the highest conductivity within the same materials class, there is much room for improvement in addition, to the outstanding potential for discovering new physics if we decrease the defects. That’s our next goal.
Professor Bharat Jalan, Chemical Engineering and Materials Science, University of Minnesota
The National Science Foundation (NSF), Air Force Office of Scientific Research (AFOSR), and U.S. Department of Energy funded the research.
Besides Jalan and Prakash, the research team also included Peng Xu, University of Minnesota chemical engineering and materials science graduate student; Cynthia S. Lo, Washington University assistant professor; Alireza Faghaninia, former graduate student at Washington University; Sudhanshu Shukla, researcher at Lawrence Berkeley National Laboratory and Nanyang Technological University; and Joel W. Ager III, Lawrence Berkeley National Laboratory and University of California Berkeley adjunct professor.