workluminescence

Workluminescence is the emission of light produced when mechanical work is directly performed on a luminescent material, such as by pressing, bending, sliding, or fracturing the material. The term emphasizes the direct conversion of mechanical energy into optical energy, rather than through indirect heating or electrical excitation. It is closely related to but distinct from other mechanoluminescent phenomena.

Mechanisms behind workluminescence can include piezoelectric or triboelectric effects that generate charge carriers which recombine radiatively, defect-center excitation created by localized lattice distortion during deformation, and microcrack–related processes that create electronic states capable of luminescence. In many materials, the light yield depends on the rate and magnitude of the applied work, the material’s crystal structure, and temperature.

Materials known to exhibit workluminescence are often described as mechanoluminescent phosphors, including certain SrAl2O4:Eu2+,Dy3+ and ZnS:Mn2+ compounds; ceramics and single crystals with strong piezoelectric responses can also display workluminescence under mechanical stimulation. The emitted spectra and lifetimes vary with material and stimulus, offering diagnostic signatures of the underlying mechanism.

Applications envisaged include self-powered stress sensing, structural health monitoring, and light sources in environments where electrical power is limited. Experimental challenges include isolating direct work-induced emission from heating and parasitic effects, and quantifying efficiency as a function of applied mechanical work. The term workluminescence is not universally adopted and overlaps with mechanoluminescence, piezoluminescence, and triboluminescence.