Kyoto, Japan -- Over the past several decades, light sources have gradually transitioned to light emitting diodes, or LEDs, and inorganic LEDs are now used across a wide range of applications. In parallel, organic LEDs, OLEDs, have become widely used in display technologies. OLEDs in particular offer significant advantages in devices such as smartphones, including higher resolution and lower power consumption. All LEDs operate based on spontaneous emission, which is inherently broadband, and OLEDs in particular produce broad emission spectra.

Narrowing this spontaneous emission toward a monochromatic limit would greatly increase its utility: a goal that has long been a central pursuit in photonics. For example, a narrower emission would achieve more highly saturated colors in LED-based displays. While organic materials offer the advantage of tunable emission wavelengths through molecular design, achieving extremely small emission bandwidths remains a major challenge.

Recent advances in molecular design have enabled the development of narrowband organic emitters, particularly multiple resonance emitters developed by Takuji Hatakeyama of Kyoto University. These materials are known for their narrow emission spectra and high color purity. However, even these emitters still exhibit significantly broader spectra than ideal monochromatic light.

Macrophages, immune cells often involved in inflammation, are regulated by the body clock (circadian clock). However, the underlying molecular mechanisms are not fully understood. Now, researchers from Kyushu University have discovered that the circadian clock protein BMAL1 transports the enzyme MFP2 into the cell nucleus, where MFP2 activates inflammatory genes and drives macrophages into a pro-inflammatory state. These findings open new possibilities for treating inflammatory diseases and cancer, potentially through timed drug therapies.

Raman optical activity, long thought to require chiral molecules or magnetic order, has been demonstrated in an achiral, nonmagnetic crystal by researchers at Institute of Science Tokyo. The effect arises through ferroaxial order, a coordinated rotation of atoms within the lattice, and is detected using circularly polarized Raman spectroscopy. These findings show that optically inactive materials can also display chirality-like optical responses and expand the scope of optical techniques for discovering new materials.  

GaN-based vertical-cavity surface-emitting lasers (VCSELs) are promising for displays, sensing, and optical communication, but improving efficiency remains challenging. Researchers have now shown that “cavity tuning,” which controls resonance wavelength, strongly affects laser performance. By analyzing variations across a VCSEL wafer, the team identified optimal mirror loss conditions and extracted device parameters. Their approach achieved 26.4% wall plug efficiency, offering guidance for next-generation high-efficiency visible-light semiconductor lasers.

An international research collaboration, including OMU, IJS, NIST and AUT, has unveiled a robust metallic state in the molecular material ytterbium cesium fulleride (Yb₂CsC₆₀) that directly tests conventional theories of electron behavior. Normally, strong interactions between electrons are expected to suppress their movement and turn materials into insulators through a process called a Mott transition. However, Yb₂CsC₆₀ represents a case where metallicity survived, suggesting that the material’s electrons were continuing to move collectively, stabilized by a different mechanism. The discovery is of relevance to future research in fields such as superconductivity, quantum matter, and next-generation electronic technologies.