Does anyone know why white LEDs are so expensive? Looking through the
Mouser catalog, I noticed that $2 a piece is a cheap as they get, versus
$0.10 for Red/Green/Yellow. Why is that?
Whites, I believe, use fluorescence in order to generate the apparent white.
Since fluorescence is almost always towards longer wavelengths, they require
blue led technology to generate the primary source of energetic photons which
then stimulate the fluorescent responses in the rare-earth materials. Blue leds
are more expensive to begin with, partly because the processes they use are
"difficult" and partly because Cree, I believe, has a patent on one of the key
wafer types often used (silicon carbide?) and anyone using that technology has
to pay a higher than usual price for access to it.
I suspect that many of the applications which would otherwise consider the use
of blue leds for aesthetic purposes (product sales) don't believe that blue
counts for enough additional value in their products to be worth the very high
cost, so they use other colors that are much cheaper and live with it. So the
volume on blue doesn't pick up that quickly, on its own legs. So, probably, the
price of blue leds is being more driven by the white led usage and that itself
is more driven by flashlight sales, I'd guess.
That's just my own meandering and I'm probably wrong on several counts, at
least. It may also be that there is a perceived value to white and that the
number of players is small and the market 'controlled' to a sense (at least to
the degree that Cree controls it), but I've no idea about that. In any case,
they are more expensive.
Perhaps Don K. will chip in here and inform us all about it or provide a link to
a web site that does.
Jon