ceases to impress that many of the things we take for granted today were the
result of accidents or unintended properties discovered when trying to create
something else. Such is the case with a breakthrough by researchers at the
University of Michigan that has produced a material that may be able to one day
reduce the cost of OLED screens and lighting.
Researcher Jinsang Kim and other colleagues developed a new class
of organic material that shines with phosphorescence that has only
been seen previously in non-organic compounds. Kim and the other researchers
developed a material that needs no metal, unlike the current materials, and can
radiate light in different colors. The new material needs no precious metals
like current non-organic OLEDs require, thereby reducing costs.
The new material is able to radiate white in visible light; and in ultraviolet
light, they radiate blue, green, yellow, and orange. The composition of the
material can be changed to emit different colors as well making the new
material ideally suited to color tunable lighting.
The unique phosphorescent properties of the material was discovered when a
former doctoral student Kangwon Lee was researching a biosensor. The phosphors
he discovered have use in the biosensor application and were then studied and
tweaked for use as pure organic metal-free luminous materials. The new luminous
material may one day be used to create larger and cheaper OLED panels for
electronics in addition to the solid state lighting applications.
"Purely organic materials haven't been able to generate meaningful
phosphorescence emissions. We believe this is the first example of an organic
that can compete with an organometallic in terms of brightness and color tuning
capability," said Kim, an associate professor of materials science and
engineering, chemical engineering, macromolecular science and engineering, and
The new phosphors have a quantum yield of 55%. Science Daily reports
that quantum yield is a measure of a materials efficiency and brightness in as
far as it can dissipate energy as light rather than heat as it returns to
ground state from an excited state. The phosphors created by Kim create light
from molecules of oxygen and carbon known as "aromatic carbonyls."
aromatic carbonyls that Kim created are unique in that they form tight halogen
bonds with halogens in the crystal to pack molecules tightly. That tight
packing of the molecules suppresses vibration and heat energy losses as the
electrons return to ground state.
quote: That tight packing of the molecules suppresses vibration and heat energy losses as the electrons return to ground state.
quote: It never ceases to impress that many of the things we take for granted today were the result of accidents or unintended properties discovered when trying to create something else.