This flat OLED (Organic Light-Emitting Diode) tile light by OSRAM is transparent whether on or off.
"This means that partitions that are almost invisible by day can provide a pleasant diffused light at night, and as the relative strengths of the beams in the two hemispheres of the tile can be adjusted within a wide range, allowing the surface light source to be configured for light to shine only in the required direction, the technology could bring a new edge to the shape and character of lighting design," according to Gizmag.
This could lead to many interesting lighting applications. OLEDs are currently used in flat screen color displays in cell phones, TVs and computers.
OLED Tile Light
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