Solid State Lighting Semiconductor Spectroscopy & Devices

1. Solid State LightingSemiconductor 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. energyboomer.typepad.com What is solid state lighting? Why solid state lighting? How to achieve white LEDs? Around 20 % of Earth's total power consumption is used for lighting! Solid state lighting is the term for devices of light sources made of a material called semiconductors, i.e. light emitting diodes (LED). My research at Strathclyde: Yellow phosphor converts the blue light of a InGaN/GaN LED (typical material) into a broad visible spectrum, which adds up to white light. www.otherthings.com Figure 1: LEDs of different colours. www.wikipedia.org Applications for LEDs: Figure 5: Optical image of a blue LED with phosphor. Why solid state lighting, again? www.nasa.gov www.wikipedia.org garbagebin.wordpress.com diytrade.com Figure 2: Traffic lights, car headlights, room lighting… Figure 3: Earth at night from space. 1) Very efficient transformation of energy into light 2) Very long lifetimes (20 000 – 50 000 hours) Evolution of lighting Over 150 years ago… www.campsolution.com LED is the light source of the present generation! 60-80 years …till present later… This poster was prepared by Jochen Bruckbauer. My research at Strathclyde is funded by the Strathclyde University research fund. 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.