Lighting efficiency

Lighting efficiency for incandescent light bulbs are only around 2 to 3 percent. With fluorescent tubes, you may get around 15 percent. It would be interesting to find ways to improve on these figures. Just imagine the amount of energy we can save. The following may contain something relevant. René T. Wegh, Harry Donker, Koenraad D. Oskam and Andries Meijerink have written a paper in Science 1999, 283, 663 with the following abstract.

For mercury-free fluorescent lamps and plasma display panels, alternative luminescent materials are required for the efficient conversion of vacuum ultraviolet radiation to visible light. Quantum cutting involving the emission of two visible photons for each vacuum ultraviolet photon absorbed is demonstrated in Eu³⁺-doped LiGdF₄ with the concept of downconversion. Upon excitation of Gd³⁺ with a high-energy photon, two visible photons can be emitted by Eu³⁺ through an efficient two-step energy transfer from Gd³⁺ to Eu³⁺, with a quantum efficiency that approaches 200 percent.