Lighting accounts for about 22% of the electricity consumed in buildings in the United States, and 40% of that amount is eaten up by inefficient incandescent light bulbs. The search for economical light sources has been a hot topic.

Recently, scientists have made important progress towards making white organic light-emitting diodes (OLEDs) commercially viable as light source. As reported in a latest Nature article, even at an early stage of development this new source is up to 75% more fficient than today's incandescent sources at similar brightnesses. The traditional light bulb's days could be numbered.

The organic layers of OLED are only 10 nanometers thick, and transparent when turned off, they can be built as light-emitting ceilings or windows. Currently, the biggest barrier to large scale production of OLED is the high cost of the encapsulation layer to prevent the damage of moisture, commented by Stephen Forrest of the University of Michigan, the coauthor of the Nature article.