<p>Organic long-persistent-luminescent (OLPL) materials that exhibit hour-long
photoluminescence have advantages over inorganic materials, such as a sustainability,
flexibility, and processability. The OLPL materials store the absorbed energy
in an intermediate charge-separated state, but this charge-separated state is
unstable to oxygen and does not exhibit persistent luminescence in air. The
excitation wavelength of OLPL can be controlled by electron-donor and -acceptor
materials, but previous materials require absorption mainly in the ultraviolet region.</p><p>
Here, we show OLPL systems that exhibit a persistent luminescence in air
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, as opposed to previous OLPL systems that depend on electron diffusion.
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..</p>
Air-Stable and Visible-Light-Active P-Type Organic Long-Persistent-Luminescence System by Using Organic Photoredox Catalyst
