January AMP_Digital

A D V A N C E D M A T E R I A L S & P R O C E S S E S | J A N U A R Y 2 0 1 9 1 3 EMERGING TECHNOLOGY NEW SOLAR CELL MATERIAL: ULTRA-THIN SILVER FILMS Researchers at Ruhr-Universität Bochum and the University of Wupper- tal, both in Germany, developed a new fabrication process for transparent ul- tra-thin silver films. The material may help build highly efficient solar cells and LEDs. “Precursors for the fabrication of ultra-thin silver films are highly sen- sitive to air and light,” explains Nils Boysen. The silver precursors can be stabilized with fluorine, phosphorus, or oxygen. “However, these elements con- taminate the thin films as well as the equipment used for the production,” he adds. In the course of his master’s the- sis, Boysen and his colleagues devel- oped an alternative solution to tackle the problems associated with common silver precursors. The team created a chemical silver pre- cursor, where the silver is surrounded by an amide and a carbene, which is stable with- out requiring fluorine, phosphorous, or oxy- gen. They demonstrat- ed that a silver thin film can be applied to an electrode with the new precursor by atomic layer deposi- tion. In the process, the gaseous precursor is transported to the electrode and a silver film is deposited there as a layer with a thickness of merely a few atoms. Due to its thinness, the silver film is transparent. “As the process can be operated under atmospheric pressure and at low temperatures, the conditions for indus- trial production are quite favorable,” says Anjana Devi. Following a series of tests, the re- searchers showed that the thin silver films manufactured using this method are pure and electrically conductive. www.ruhr-uni-bochum.de/en , www.uni- wuppertal.de/en. FABRIC POWER SUPPLY FOR WEARABLE DEVICES A key challenge facing developers of wearable biosensors is the absence of a lightweight, long-lasting power supply. Scientists at the University of ENER Y TRE DS UMass researchers developed a method for making a charge-storing system that is easily integrated into clothing. Massachusetts, Amherst, now say they have developed a method for making a charge-storing system that can be eas- ily integrated into clothing for embroi- dering a charge-storing pattern onto any garment. “Batteries or other kinds of charge storage are still the limiting compo- nents for most portable, wearable, in- gestible, or flexible technologies. The devices tend to be some combination of too large, too heavy, and not flexible,” the scientists explained. Their new method uses a mi- cro-supercapacitor and combines va- por-coated conductive threads with a polymer film, plus uses a special sewing technique to create a flexible mesh of aligned electrodes on a textile backing. The resulting solid-state device pos- sesses a high ability to store charge for its size and other characteristics that allow it to power wearable biosensors. umass.edu. With a $1.08 million contract award from the United States Advanced Battery Consortium LLC, a materials engineering research team at Worcester Poly- technic Institute, Mass., will extend development of its novel process to recy- cle spent Li-ion batteries. The team will also produce new cathode materials to reduce cost and increase energy density in these automotive batteries. wpi.edu. BRIEF From left, Anjana Devi and Nils Boysen in the lab in Bochum. Courtesy of RUB/Marquard. Prof. Yan Wang with a sample of the cathode materials he is making at WPI.