Generating white light from electricity with maximum efficacy has been a long
quest since the first incandescent lamp was invented by Edison at the end of the
19th century. Nowadays, semiconductors are making reality the holy grail of
converting electrons into photons with 100% efficiency and with colours that can
be mixed for white light illumination. The revolution in solid-state lighting (SSL)
dates to 1994 when Nakamura reported the first high-brightness blue LED based
on GaN semiconductors. Then, white light was produced by simply combining a
blue dye with a yellow phosphor. After more than a decade of intensive research
the performance of white LEDs is quite impressive, beating by far the luminous
efficacy of compact fluorescent lamps. We are likely close to replacing our
current lighting devices by SSL lamps. However, there are still technological and
fabrication cost issues that could delay large market penetration of white LEDs.
Interestingly, SSL may create novel ways of using light that could potentially
limit electricity saving. Whatever the impact of SSL, it will be significant on our
daily life.
The purpose of this special cluster issue is to produce a snapshot of the current