How to create a phosphorescent material of high luminous intensity?

The main difficulties observed to obtain a phosphorescent material

Stabilize the glow property

Today, there is a wide variety of commercial glow pigments, which are essentially green or blue. It is therefore easy to obtain a phosphorescent material. The mixture of a commercial glow pigment in an ink and/or paint allows to obtain easily a phosphorescent solution.

The difficulty is if you wish a strong glow intensity in the dark with a stability of the property throughout the production, with a recurrence. By experience, we know that phosphorescent materials are extremely sensitive to shear forces, that an uncontrolled addition of an additive, a dye, a glow pigmentary charge can irremediably reduce the luminous intensity in the dark from several hours to a few minutes.

Controlling color of a glow powder and pigment

Another major challenge is to achieve color control by day and night. Our teams use photochemical cascade to optimize :

• the color: violet, blue, green, red, orange, yellow, black... ;
• the luminous intensity ;
• the duration of glow emission in time;
• the matrix and deposition method: ink (screen printing, pad printing, syringe filling), paint (high or low pressure pneumatic spray, aerosol can), composite, plastic...

The process from start to finish

To be able to offer this performance, we develop our glow powder pigments but only deliver our inks (screen printing, pad printing,...). This allows us to control all the steps from the preparation of the pigment powder mixture to the formulation of inks and paints.

All our glow materials are produced in our factory (33, France) and controlled by our quality department. The phosphorescence properties of our products are characterized by :

• the emission spectrum which gives access to the variation of the intensity of the emitted light according to the wavelength;
• the quantum yield which informs on the luminescent performance of the material. It varies from 1 (all the absorbed photons are re-emitted) to 0 (the compound is not luminescent);
• the lifetime which is the characteristic time of the emission. In most cases, the fluorescence follows an exponential probability law in exp (- t/τ), where τ is the lifetime. The order of magnitude of the lifetime of many fluorescent substances is the nanosecond (billionth of a second). In phosphorescence, the lifetime can reach several hours.