Light-emitting diodes are prime candidates for replacing inefficient incandescent bulbs but have a few things working against them. They can provide a pleasing warm light or they can be energy-efficient, but they haven’t been able to be both at the same time. On Tuesday, two small companies showed off an LED lamp that’s both very power-efficient and produces a light similar to that of a standard tungsten or halogen bulb. The LEDs in the lamp shine through a thin layer of “quantum dots,” a scattering of particles of very small but precisely controlled size.
