If you tell your mother that your science class today is called "tricks with water" then she might tell you to try not to get wet. But in this class, getting wet is half the fun, along with cast iron bombs that explode, paint cans that implode, lead that turns into gold, a cruise liner that floats in a cup of water, and water that boils when it gets cold. Its all part of a Materials Science from CU class that teaches the basics of phase change, bouyancy, pressure, and vacuum, one of many MSFCU classes presented to 3,800 K5-K9 students by LCMRC staff over the past year.
LCMRC researchers have developed a method for manipulating particles by light without touching them by using liquid crystals as a light-controlled host fluid. The LC host reduces the illumination required by factors up to 10,000X relative to direct manipulation with optical tweezers, to the extent that lasers are no longer needed for many applications. LCMRC designed and synthesized photosensitive azobenzene monolayers control the LC orientation, which in turn moves the particles. The image illustrates that dynamic complex patterns can be generated, making optical manipulation suitable for a number of applications and development of new types of photoresponsive composite materials.
Center researchers are collaborating with spin-off Displaytech (now part of Micron Technologies) to develop ferroelectric liquid crystal (FLC) materials for application in picoprojectors. The high-quality time sequential color and high brightness enabled by FLC switching speed, and high fill factor and ultra-small pixels achievable with FLCs makes FLC-on-silicon the choice display technology for picoprojectors. FLC-based pico-projection continues to advance with the $99 POPVIDEO iphone projector shown in the image, recently introduced by Micron/Displaytech.
In a photovoltaic cell, an incident photon creates an electron (black
circle in top sketch) and a hole (open circle). For maximum efficiency,
the opposite charges should be swept to opposite electrodes of the
device (arrows) before they have a chance to recombine. The efficiency
is further enhanced if a wide band gap organic semiconductor (e.g. P3HT)
is grown on the surface of silicon. The wide gap (shown in red) blocks
electrons from spilling into the anode. Organic semiconductors provide
great design flexibility in tuning band offsets. A challenge, however,
is controlling the defects (dangling bonds) at the interface with Si,
which degrade device performance. PCCM scientists Sturm, Kahn, Loo and
Schwartz have solved the surface passivation problem, and have achieved
quite high efficiencies (~10%) in hybrid devices. An important advantage
is that these devices can be made at low temperatures (<100o C).