ADVANCED MATERIALS & PROCESSES | MAY/JUNE 2023 1 1 PROCESS TECHNOLOGY NEXT-GEN SOLAR CELLS WITH LARGE PEROVSKITES A team of scientists from Penn State, State College, developed a new method to fabricate large perovskite devices that is more cost- and time- effective than was previously possible. The researchers say their technique could accelerate future materials discovery. “This method we developed allows us to easily create very large bulk samples within several minutes, rather than days or weeks using traditional methods,” says lead researcher Luyao Zheng. “And our materials are high quality—their properties can compete with single-crystal perovskites.” The team used a sintering method called the electrical and mechanical field-assisted sintering technique (EMFAST) to create the devices. Conventional processes for making perovskites involves wet chemistry—the materials and in the production of computer microchips. Because the process requires materials to be heated at thousands of degrees, organic polymers do not fare well. Scientists at the Cornell lab are studying how vapor-deposited polymers interact with bacterial pathogens and how bacteria, in turn, colonize polymeric coatings, from the paint used in ship hulls to the coating for biomedical devices. The researchers set out to develop a different approach to diversify CVD polymers by borrowing a concept from conventional solutions synthesis— the use of a so-called magic solvent, i.e., an inert vapor molecule, that isn’t incorporated into the final material, but instead interacts with a precursor in a way that produces new material properties at room temperature. The solvent in this case interacted with a common CVD monomer via hydrogen-bonding. This method can be applied to methacrylate and vinyl monomers for most anything with a polymer coating. cornell.edu. are liquefied in a solvent solution and then solidified into thin films. According to the scientists, these materials have excellent properties, but the approach is expensive, inefficient for creating large perovskites, and the solvents used may be toxic. Because it uses dry materials, the EM-FAST technique opens the door to include new dopants, ingredients added to tailor device properties, that are not compatible with the wet chemistry used to make thin films. The new process also allows for layered materials—one powder underneath another—to create designer compositions. In the future, manufacturers could design specific devices and then directly print them from dry powders. psu.edu. STRONGER THIN FILMS WITH MAGIC SOLVENT Researchers at Cornell University, Ithaca, N.Y., created a new all-dry polymerization technique that uses reactive vapors to create thin films with enhanced properties, such as mechanical strength, kinetics, and morphology. The synthesis process is gentler on the environment than traditional high-temperature or solution-based manufacturing and could lead to improved polymer coatings for microelectronics, advanced batteries, and therapeutics. Chemical vapor deposition (CVD) is a common process used to make defect-free inorganic nanolayer materials in semiconductor manufacturing BRIEF Alleima, Sweden, a manufacturer of advanced stainless steels and special alloys, opened a new hydraulic and instrumentation tubing factory on March 15 at its Mehsana Mill in Gujarat, India. Company officials say the factory will help meet a growing demand for locally manufactured products. alleima.com. Micrograph of an initiated chemical vapor deposition coating. Courtesy of Pengyu Chen/Cornell University. FAST-synthesized perovskite samples at various sizes. Courtesy of Penn State.
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