Although colored light is useful for more creative  installations, white light remains the holy grail of LED technology.Until a true white is possible,researchers have developed three ways to deliver it;
--Blendthe beams.This technique involves mixing the light from multiple single colored devices. (Typically red,blue and green.) Adjusting the beams relative intensity yields the desired color.
--Provide a phosphor coating. When energized photons from a blue LED strike a phosphor coating, it will emit light as a mixture of wavelengths to produce a white colour.
--Create a light sandwich.Blue light from one LED device elicts orange light from an adjacent layer of adiiferent material.The complimentary colors mix to produce white of the three methods the phosphr method seems to be the most promising technology.
Another shortcoming of early LED designs was light output, so reserchers have been working on several methods for increasing lumens per watt. A new 'doping' technique increases light output several times over compare to earlier genertions of LEDs. other methods under dev. include
--Poducing larger semiconductors.
--Passing larger currents with better heat extraction
--Designing a different shape for the device
--Improving light conversion efficiency
--Packaging several LEDs withing a single epoxy dome.