LED lighting

colourful solutions

colourful solutions

The most recent Nobel Prize for physics was awarded to the developers of the blue light emitting diode (LED), not something I’ve known much about until now, but a recent article or two in Cosmos magazine has more than whetted my appetite about the future of LEDs.

This is an amazing technology that I feel I should be availing myself of, and advertising to others. But first I need to get a handle on how the technology works, which I suspect will be no mean feat. Here goes.

The name of Oleg Losev should be better known. This short-lived Russian (he died of starvation during the Siege of Leningrad in 1942 aged 38) is now recognised among the cognoscenti as the father of LEDs. He did some of the world’s first research into semiconductors. Semiconductors are materials whose electrical properties lie between conductors such as copper and insulators such as glass. While working as a radio technician, Losev noticed that when direct current was passed through a point contact junction containing the semiconductor silicon carbide (carborundum), greenish light was given off at the contact point, thus creating a light-emitting diode. It wasn’t the first observation of electroluminescence, but Losev was the first to thoroughly describe and accurately theorise about the phenomenon.

LED technology continues to develop, but now it seems to have reached the stage where it’s not only commercially viable, but has eclipsed all other forms of lighting. I’m more than a bit interested in promoting this form of lighting for the Housing Association I’m living in, especially as the relatively expensive fluoro bulbs in my own home keep blowing. 

In issue 60 of Cosmos, Australia’s premier popular science mag, Alan Finkel waxed lyrical on the coming of age of LED lighting, which he now has installed in his home:

Our LEDs are brighter than the [halogen] lights they replaced, they use less electricity, they mimic the colour of sunlight, they have not visibly aged since they were installed, they work with dimmers, and they are safer in the ceiling cavity because they do not run nearly as hot as the halogens

It’s only quite recently that LED lighting for homes – and everywhere else that bright sunshine-like light comes in handy – has become available on competitive terms, and to understand why we need to return to the history of LED development.

Oleg Losev’s creation of the first LED in 1927 wasn’t capitalised on for decades, but experiments in the fifties in the USA reported infrared emissions from semiconducting materials such as gallium arsenide, gallium antimonide and indium phosphide. By the early sixties the first practical applications of infrared and visible red LEDs emerged. Ten years later, yellow LEDs were invented, which increased the brightness by a factor of 10. In the mid-seventies, optical fibre telecommunications systems were developed by the creation of semiconductor materials adapted to the fibre transmission wavelengths, further enhancing brightness and efficiency. It was around this period that we started to see patterned LEDs in radio and TV displays, and in calculators and watches. At first these were quite faint, and expensive to manufacture, but many breakthroughs in the field have brought down costs while improving efficiency markedly, and the field of high power LEDs has experienced rapid progress, particularly with the development of high-brightness blue by the Nobel prize winning Japanese researchers in the early nineties. The blue LEDs could be coated with a material which converted some of the blue light to other colours, resulting in the most effective white LED yet created. The blue LED was also the last piece of the puzzle for creating RGB (red, green, blue) LEDS, enabling LEDs to produce every visible form of light.

The future for LEDs is so bright that it’s been called the biggest development in lighting since the electric light bulb, The question for the everyday consumer like me, then, is – should I get on board with it now, or should I wait until the technology becomes even cheaper and more energy-efficient?

As we know, the incandescent bulb is going the way of the trilobite. Hugely sucessful worldwide for decades, it has been outcompeted in recent times by the cheaper and more efficient CFL (compact flourescent lamp), and its extinction has been assured by state energy laws. But the CFL is now recognised as a stop-gap for the far more versatile and revolutionary technology of LED. LEDS are already beginning to outstrip CFLs in terms of life-span, but up-front costs are high. As this American C-net article has it,

The minimal energy savings you get from going from CFL to LEDs reflects that LED bulbs are only slightly more efficient, when measured on lumens per watt. And, of course, CFLs have come way down in price over the past few years, while LEDs are still at the top of a projected downward cost curve. If you have incandescent bulbs, saving $4 a year with an LED is more compelling, but that’s still a long pay back.

So for many of us it’s a matter of waiting and watching those costs diminishing down to the proportions of our meagre bank balance. Meanwhile, it will be fascinating to see where LED technology takes us. It’s very likely that it will outgrow the old light-socket techology, from what i’ve been reading, but that’s still a way off, and will require a real change of mindset for the average consumer.

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