Category Physics

A cross-section of a perovskite solar cell seen through a scanning electron microscope. Credit: M.Grätzel/EPFL

EPFL scientists have stabilized perovskite solar cells by integrating rubidium into them. The innovation pushes power-conversion efficiency to 21.6%, ushering a new generation of perovskite solar cells. Perovskite solar cells have great potential for providing us with cost-effective solar energy. However, heat stability is an issue, and can significantly limit the solar cell’s long-term efficiency, as the cell’s structure can degenerate over time. A solution has been to mix perovskites with other materials, such as cesium, that can improve the cell’s stability without compromising its efficiency in converting light into electrical current.

Michael Grätzel’s lab at EPFL has now in...

Example of a hologram made using a new method based on optical forces. Credit: Montelongo et al. Nature Communications

Researchers have used the pressure of light, aka optical forces or “tractor beams”, to create a new type of rewritable, dynamic 3D holographic material. Unlike other 3D holographic materials, the new material can be rapidly written and erased many times, and can also store information without using any external energy. The new material has potential applications in 3D holographic displays, large-scale volumetric data storage devices, biosensors, tunable lasers, optical lenses, and metamaterials.

Recently the researchers demonstrated the reversible optical manipulation of nanostructured materials, which they used to fabricate active 3D holograms, lenses, and memory devices...

Schematic illustration and chemical structure of semi-printed plastic solar cells in air, using food additive o-MA as solvent. Credit: Long Ye, NC State

Researchers have created an efficient, semi-printed plastic solar cell without environmentally hazardous halogen solvents. These solar cells can be manufactured at room temperature, which has implications for large-scale commercial production. Plastic solar cells, or organic photovoltaics, are popular because they are lightweight, flexible, transparent and inexpensive to manufacture, making them useful in multiple applications. Unfortunately, the halogen-containing solvents used in their manufacture are an obstacle to large-scale commercialization...

Cross-section of a 3-D printed adult human femur.

A Northwestern Engineering research team has developed a 3-D printable ink that produces a synthetic bone implant that rapidly induces bone regeneration and growth. This hyperelastic “bone” material, whose shape can be easily customized, one day could be especially useful for the treatment of bone defects in children. Bone implantation surgery is never an easy process, but it is particularly painful and complicated for children. With both adults and children, often times bone is harvested from elsewhere in the body to replace the missing bone, which can lead to other complications and pain. Metallic implants are sometimes used, but this is not a permanent fix for growing children.

“Adults have more options when it comes to implants,” said ...