ADVANCED MATERIALS & PROCESSES | JANUARY/FEBRUARY 2025 12 MATERIAL CONVERTS VIBRATIONS INTO ELECTRICITY Researchers at Rensselaer Polytechnic Institute (RPI), Troy, N.Y., are developing environmentally friendly materials that produce electricity when compressed or exposed to vibrations— think streetlights powered by the rumble of passing traffic or skyscrapers that generate electricity as they sway in the wind. The team developed a polymer film infused with a special chalcogenide perovskite compound that produces electricity when squeezed or stressed, a phenomenon known as the piezoelectric effect. While other piezoelectric materials currently exist, this is one of the few high performing ones that doesn’t contain lead, making it an excellent candidate for use in machines, infrastructure, and biomedical applications. The energy-harvesting film—only 0.3 millimeters thick—could be integrated into a wide variety of devices, machines, and structures, the scientists say. “Essentially, the material converts mechanical energy into electrical energy—the greater the applied pressure load and the greater the surface area over which the pressure is applied, the greater the effect,” explains researcher Nikhil Koratkar. The piezoelectric effect occurs in materials that lack structural symmetry. Under stress, piezoelectric materials deform in such a way that causes positive and negative ions within the material to separate. This dipole moment can be harnessed and turned into an electric current. Once they synthesized their new material, which contains barium, zirconium, and sulfur, the researchers tested its ability to produce electricity by subjecting it to various bodily movements, such as walking, running, clapping, and tapping fingers. The researchers found that the material generated electricity during these experiments, enough to power banks of LEDs that spelled out RPI. Moving forward, Koratkar’s lab will explore the entire family of chalcogenide perovskite compounds in the search for those that exhibit an even stronger piezoelectric effect. They’re also aiming toward implementing these materials at scale, where they can make a difference in more sustainable energy production. rpi.edu. EMERGING TECHNOLOGY IMPROVING SEMICONDUCTOR FUNCTIONALITY At the City University of Hong Kong, researchers are enhancing the mobility of positively charged carriers, known as holes, in inorganic semiconductors. The research team achieved this breakthrough by employing an innovative inorganic blending strategy, combining various intrinsic p-type inorganic materials into a single compound, called tellurium-selenium- oxygen (TeSeO). The TeSeO materials have shown remarkable adaptability and reliability, positioning them as a promising solution to address challenges with current semiconductors. According to lead researcher Johnny Ho, the team successfully developed air-stable, high-mobility TeSeO thin-film transistors and flexible photo- detectors that surpass conventional p-type semiconductors, such as metal oxides, metal halides, and organic materials. Ho says these new devices exhibit remarkable durability and performance, setting a new benchmark in the field, and opening new possibilities for creating high-performance and cost-effective devices and circuits in the future. www.cityu.edu.hk. ASTM International will launch a center of excellence to support standardization of critical and emerging technologies. Through a competitive process, the National Institute of Standards and Technology chose ASTM to lead this center along with several other partners. The $15 million grant will be used to focus on standards that support U.S. competitiveness and national security. astm.org. BRIEF The RPI team’s device that produces electricity when stressed could be used in a shoe that lights up when the user walks. Courtesy of RPI. Inorganic blending strategy of TeSeO semiconducting materials. Courtesy of Y. Meng et al.
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