Cost Effective and Environmentally Friendly Organic Long Persistent Luminescence (OLPL) System (No. 0196, 0197)

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A novel Organic Long Persistent Luminescence (OLPL) System provides a manufacturing and environmentally friendly solution for glow-in-the-dark materials.

The glow-in-the-dark market will see continued growth in the coming years owning to its increasing applications in various signage boards, consumer goods and bio-imaging. The glow-in-the-dark market is predicted to grow at a CAGR of 4.5% up to 2025. However, inorganic materials are mainly used as glow-in-the-dark materials for the above applications. These inorganic materials are not environmentally friendly, difficult to process for certain applications, and have a limited excitation band. Here we present a promising OLPL system developed by a group of researchers led by Prof. Ryota Kabe. The system is based on purely organic blended materials composed of electron donor, acceptor, and trap/emitter molecules which realizes an environmentally friendly and robust solution for many applications.

Lead Researcher:
Ryota Kabe

Faculty of Organic Optoelectronics Unit


  • Glow-in-the-dark paints and inks
  • Bioimaging



  • No rare earth materials
  • Soluble / ease of processing
  • Air stability
  • Broad excitation wavelength range

     Click on the images to enlarge


The technology is based on OLPL material including a p-type (hole diffusion) system that exhibits a persistent luminescence in air, ease of processability and can be excited by a wavelength from 300-nm to 600-nm. By using cationic photoredox catalysts as an electron-accepting dopant, stable charge-separated states are generated by the hole-diffusion process. By using a hole-diffusion mechanism and reducing the energy level of the lowest unoccupied molecular orbital, the OLPL system becomes stable in air and can be excited by visible light. The addition of hole-trapping material increases the LPL duration.


Media Coverage and Presentations

  News: Casting light on glow-in-the-dark materials



  Graham Garner
Technology Licensing Section