Solid State Lighting
Semiconductor Spectroscopy & Devices
Further information: jochen.bruckbauer@strath.ac.uk
Overview
Conventional light sources, like the light bulb and fluorescent lamps, are very inefficient in transforming energy into light. Due to upcoming problems in
energy supplies new and more efficient light sources have to be developed. In recent years enormous advances in solid state lighting were made in the
development and raising the efficiencies of white light sources made of semiconductors.
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What is solid state lighting?
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Solid state lighting is the term
for devices of light sources
made of a material called
semiconductors, i.e. light
emitting diodes (LED).
Why solid state lighting?
Around 20
% of Earth's total power consumption is
used for lighting!
Applications for LEDs:
Why solid state lighting, again?
www.nasa.gov
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Figure 2: Traffic lights, car headlights, room lighting…
Over 150 years ago…
My research at
Strathclyde:
Yellow phosphor
converts the blue light
of a InGaN/GaN LED
(typical material) into a
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broad visible
spectrum, which adds Figure 5: Optical image of
up to white light.
a blue LED with phosphor.
Figure 1: LEDs of different colours.
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How to achieve white LEDs?
Figure 3: Earth at night from space.
Evolution of lighting
1) Very efficient transformation of energy into light
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…till present
60-80 years
2) Very long lifetimes (20 000 – 50 000 hours)
LED is the light source
of the present generation!
later…
www.guardian.co.uk
www.wikipedia.org
Figure 4: In light bulbs a current is passed through a wire, which is very inefficient due to heating. In fluorescent
lamps electricity is passed trough a tube containing gas, which is more efficient than a light bulb, but they contain
traces of toxic materials. LEDs utilise the movement of electrons inside a semiconductor for light emission.
This poster was prepared by
Jochen Bruckbauer. My
research at Strathclyde is
funded by the Strathclyde
University research fund.