Researchers at Kyushu University have developed a cheaper, easier-to-make luminous paint. (Provided by Kyushu University)

FUKUOKA--Researchers here developed luminous paint that is cheaper to make and glows for many hours in the dark, thereby offering a range of applications that could help people in an emergency.

Luminous paints are conventionally used for faces of wristwatches, emergency exit signs and so on.

But the researchers at Kyushu University said it could now also be used to light up ceilings when people are evacuating in emergencies and illuminate clothes.

Their achievement was published in the British scientific journal Nature on Oct. 3.

Existing luminous paints use pricey rare earth elements. The manufacturing process requires that the ingredients are heated to in excess of 1,000 degrees.

The team developed a paint that can emit light for more than 30 minutes by melting and mixing two kinds of materials used for organic light-emitting diodes.

When exposed to light, electrons make holes inside the newly developed luminous paint, just like solar cells. The paint emits light when electrons fill the holes.

Production costs for the new paint are around 10 percent of those for conventional luminous products. The color of light of the new material can easily be changed, according to the researchers.

“The duration of light emissions and strength of light can still be improved. There are lots of ways the improved use of luminous paints can benefit society,” said Ryota Kabe, an assistant professor of chemistry at the university.