OLED displays demand materials that can emit light with extreme efficiency, while deep-tissue medical imaging relies on compounds that absorb light in ways that minimise damage to living cells. These two worlds have long required separate solutions, until now.
Researchers at Kyushu University have developed a single organic molecule that can excel in both roles, potentially transforming consumer electronics and biomedical diagnostics alike.
The study showcases a breakthrough material that delivers efficient light emission for next-generation screens and strong light absorption for high-precision imaging deep inside the body.
The discovery could pave the way for devices that bridge entertainment and healthcare, using one molecule to power brighter displays and enable safer, sharper diagnostics.
Merging two elusive properties
OLEDs dominate modern displays, from smartphones to large televisions. Improving their efficiency often involves thermally activated delayed fluorescence (TADF).
This process converts normally wasted triplet-state energy into light-emitting singlet states using ambient heat. Materials with strong TADF can make displays brighter and more energy-efficient.
In medicine, deep-tissue imaging demands materials that work with low-energy, near-infrared light to reduce scattering and damage. Two-photon absorption (2PA) achieves this by allowing a molecule to absorb two lower-energy photons at once.
The technique excites only tissue at the laser’s focal point, enabling sharper, safer imaging.
Combining strong TADF and high 2PA in one molecule has long been a challenge. TADF works best in twisted molecular structures with separated electron orbitals. 2PA typically requires planar structures with high orbital overlap.
These demands often conflict, making dual-function molecules rare.
To solve this, the Kyushu-led team designed a molecule called CzTRZCN. It combines an electron-rich carbazole unit with an electron-deficient triazine core.
Cyano groups fine-tune the orbital arrangement by pulling electrons toward them.
This architecture lets the molecule act as a “switch.” During absorption, CzTRZCN maintains enough orbital overlap for efficient 2PA. Once excited, it changes structure to separate orbitals, enabling TADF.
The team validated this dual behaviour with theoretical calculations and experiments. In an OLED device, CzTRZCN reached an external quantum efficiency of 13.5%, a record for triazine-based TADF materials.
It also showed a high 2PA cross-section and strong brightness, making it promising for medical imaging.
Lead researcher Youhei Chitose said the molecule’s metal-free, low-toxicity nature makes it highly biocompatible, ideal for medical probes.
Time-resolved fluorescence microscopy could particularly benefit from the material’s performance.
Toward broader applications
The study outlines a strategy for creating molecules with different orbital arrangements for light absorption and emission. This approach could inspire new multifunctional materials beyond medical and display uses.
Chitose said the team plans to expand the design to cover more emission wavelengths and to collaborate with biomedical and device engineers. Possible applications include in vivo imaging, wearable sensors, and next-generation OLED displays.
By bridging photoelectronics and bioimaging, the work opens doors for devices that seamlessly cross between consumer electronics and healthcare.
If scaled, CzTRZCN could help create brighter, more efficient screens and more precise, less invasive imaging tools in medicine.
The study is published in the journal Advanced Materials.