selfilluminated

Self-illuminated, or self-luminous, describes objects that emit light from an internal or inherent energy source rather than reflecting light from an external source. The term covers natural phenomena such as bioluminescence in living organisms and astronomical objects that generate their own light, as well as man-made devices and materials designed to emit light.

Light can be produced by several mechanisms. Luminescence includes fluorescence and phosphorescence, where energy absorption leads to light emission; phosphorescence lasts after excitation ends. Chemiluminescence is light produced by a chemical reaction, and bioluminescence is chemiluminescence produced by living organisms. Electroluminescence, a key mechanism for modern self-illuminating devices, emits light when electrical energy drives electron–hole recombination, as in LEDs and OLEDs. Some self-illuminated signs use radioactive sources or chemiluminescent materials, or phosphorescent pigments that glow after light exposure.

Natural self-illumination is used by organisms for signaling, attraction, or camouflage. Artificial self-illumination is common in signage (such as exit signs), displays, backlighting, and decorative lighting. Phosphorescent paints and tritium-based signs provide light without continuous power, while LEDs and OLEDs offer controllable, energy-efficient illumination.

Limitations and considerations include varying brightness and emission duration by mechanism, and safety or environmental concerns with certain radioactive sources. Self-illumination is distinct from reflected light and from passive luminescent materials that require charging by external light.