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 2 0 1 5 NANO BULB SHINES LIGHT ON MATERIALS ADVANCEMENTS Scientists at Rice University have developed what may be considered the world’s smallest incandescent light- bulb. The assembled collections of near-nanoscale materials that absorb heat and emit light are promising for advances in sensing, photonics, and perhaps computing platforms beyond the limitations of silicon. Their research one-ups a recent technique developed by the lab that uses carbon nanotubes to channel heat from mid-infrared radiation to improve the efficiency of solar energy systems. The new strategy combines sev- eral known phenomena into a unique configuration that also turns heat into light—but in this case, the system is highly configurable. Essentially, the re- searchers made an incandescent light source by breaking down a one-element system—the glowing fila- ment in a bulb—into two or more subunits. Mixing and matching the subunits could give the system a va- riety of capabilities. The system relies on non-Hermitian physics, a quantum mechanical way to describe “open” systems that dissipate energy—in this case, heat—rather than retain it. Though commercial incandescent bulbs have given way to LEDs for their energy efficiency, the scientists said, incandescent lamps are still the only practical means to produce infrared light. The nano-bulb effect produced by the Rice University researchers in- troduces new opportunities in the ad- vancement of materials in many fields. The opportunities may also be great for next-level classical computing. “The International Technology Road- map for Semiconductors (ITRS) under- stands that semiconductor technolo- gy is reaching saturation and they’re thinking about what next-generation switches will replace silicon transis- tors,” the scientists said. “ITRS has pre- dicted that will be an optical switch, and that it will use the concept of par- ity-time symmetry, as we do here, be- cause the switch has to be unidirec- tional. It sends light in the direction we want, and none comes back, like a diode for light instead of electricity.” rice.edu . FILM POWERS UP INFRARED LIGHT A research team led by Hans Ågren at KTH Royal Institute of Technolo- gy, Stockholm, has achieved a break- through in converting invisible infra- red light into power. The team devel- oped a film that can be applied on top of ordinary solar cells, which would en- able them to use infrared light in ener- gy conversion and increase efficiency by 10% or more. Photosensitive materials used in solar cells, such as the mineral per- ovskite, have a limited ability to re- spond to infrared light. The solution discovered by KTH researchers was to combine nanocrystals with chains of microlenses. “The ability of the microlenses to concentrate light allows the nanopar- ticles to convert the weak IR light ra- diation to visible light useful for solar cells,” Ågren says. The team’s research progress has been patented. www.kth.se/en. NANOTECHNOLOGY BRIEF The Nanoaugmented Materials Industry Summit took place last November in Kyoto, Japan. Attending this annual event were hundreds of leading companies and institutes working with single wall carbon nanotubes, a “material of the future.” Airbus Defense and Space, Lufthansa Technik Intercoat, BASF, Trelleborg Applied Technologies, BYK Additives, Rice University, Fraunhofer IPA, and other industry leaders and distinguished scientists shared their insights on recent developments in nanotube industrial applications. www.naum.world . This novel film captures infrared light and converts it to solar energy. Courtesy KTH Royal Institute of Technology. An array of thermal light transmitters imaged by an electron microscope. Courtesy of Naik Lab/Rice University.