Solid State Lighting: The Past, Present and Future of LED Technology
Posted in: July 2014
LED, or solid state lighting, technology is not really new. In fact, it has been around for over 100 years. Electroluminescence, the phenomenon that results in light from an LED, was first observed in 1907. Initially, this discovery made little impact outside of the scientific world. It would be another 55 years before LEDs made it into commercial applications. In 1962, the first commercial LEDs were sold to IBM. They replaced tungsten bulbs in punch card readers, and cost about $130 each.
These new lights were significantly more expensive than the tungsten bulbs they were replacing, but they provided solutions to problems in these early computers, including the reduction of heat created by bulbs, lowering the power demand, decreasing the size of the machine, and also providing better accuracy by using the directional infrared light created by the LED.
Immediately, LEDs were identified as valuable technology but the practicality of their use was a mystery to many. Light produced from these first LEDs was minimal. The circuitry and technology behind LEDs was weak and prone to premature failure. Early bulbs did not live up to their potential.
LEDs Live Forever
An LED will theoretically last forever. LEDs will always produce light when power is properly applied. Over time, the amount of light will decrease. Eventually, the amount of light may be so low that the human eye cannot see it. When an LED reaches this point it is still not “dead,” it is just producing light that is not visible to our eye.
However, this state of unperceivable light is often not the fate of LEDs. Instead, the driver or other controls behind the LED fail first. It is in this area that technological developments have most benefited commercial LEDs. In order for an LED to be commercially viable, it must be reliable. Better technology in the drivers and controllers is the best way to build a more reliable LED lamp.
Early commercial LEDs had countless problems related to the technology around them. In many instances, materials that bond circuits failed and the LEDs stopped working. Another problem was from materials used to encapsulate the diode. The encapsulates started to yellow and change color as they aged. This material aging resulted in diminished output or color changing. These changes to the light output or color were seen as a failure of the LED, not a failure of the supporting hardware.
Not a White Light
Another, more visible problem with LEDs must be mentioned. The light that many of the early, commercial LEDs produced was not pleasing to people. The light was often bluish-white and lacked “warmth.”
It is a little known fact that no LEDs are white. You can make LEDs in almost color but white. This is hard to believe because most of us have seen LED lamps that are white light. However, just one color LED cannot produce this white light. There are two common ways to make white light from LEDs. The first is to mix red, green, and blue LEDs to create white light. The other option is to use phosphor in the LED module. The LED light reacts to the phosphor, similar to the reaction in a fluorescent tube light, and the light that is output appears white. Both of these methods have their pros and cons but the use of phosphor became the more common method.
The use of phosphor proved to be easier, cheaper, and more reliable. This is not to say that it was perfect. In early commercial LED manufacturing, the color rendering of the LEDs was not closely monitored. This resulted in LED lamps that were manufactured in the same place around the same time but did not put off the same color of light. This inconsistency further hindered the widespread acceptance of LEDs.
Lastly, it is important to address the most obvious of all obstacles that LEDs have faced. This is of course: COST. The driver or controller needed to provide the correct power to these lights made the early costs of LED production expensive. In essence, every LED is backed by a tiny computer.
Initial high manufacturing costs made it difficult to see a practical return on investment for most applications. The good news is that advances in LED production, driver design, heat management, and new guidelines or standards have brought the consistent quality of all LEDs up to a higher level, while at the same time reducing production costs.
Organizations focused on lighting efficiency have stepped in to offer structure and standards for the industry. The Design Lights Consortium (DLC) has become an industry leader for verifying efficient lighting solutions. The DLC tests the color rendering and life expectancy claims of countless lighting products.
Their objective is to bring facts and test data to the public so that consumers may make an informed decision. Organizations like the Underwriters Laboratory or ETL already perform tests to ensure product safety but there was no one testing the actual performance. The DLC continues to work toward a universal set of standards that will guide manufacturers to produce higher quality LEDs and help the consumers to make educated decisions. Regulating this industry or creating guidelines is no easy feat considering how fast it is advancing and how quickly practices in manufacturing and design can change.
LED technology has progressed at an amazing pace and today’s solid state lighting solutions are better and brighter than ever. LEDs became commercially valuable in just the past few decades.
Advances in production improved efficiency and light output of commercial LED lights, while lowering costs. The LEDs produced today are over twice as efficient as some produced only five years ago. This trend will continue and LED efficacy will go up as production costs go down. This rapidly developing field not only brings new technology to consumers but also brings new producers to the technology.
Today, it is estimated that 200 new companies per month begin manufacturing LED products. This number will continue as technology advances and LED lighting becomes more mainstream.
Organic Light Emitting Diodes
Beyond the promise of better efficiency, the promise of better products is in the near future for LEDs. One very exciting, new technology is OLED technology or Organic Light Emitting Diodes. This will allow LEDs to be manufactured on flexible surfaces. This could revolutionize the way that we think about and design lighting and electronics. Imagine a display that could be folded in half like a piece of paper. Or imagine a material that could be rolled onto a wall or floor and turn that surface into an OLED display. A few manufacturers have already started using OLEDs in their products. Things like curved television screens and smartphone screens utilize OLED technology. This technology is new and the costs are still high but we can safely assume that we will see more applications and lowers costs in the very near future.
Increased efficiencies, improved light output, and lower production costs will help to pave the road for the commercial success of all LEDs. This success will in turn relieve stress from our burdened electrical infrastructure and enable renewable energy resources to more easily fit into our daily lives by reducing the overall demand.
The future of solid state lighting is wide open. Within the next three years, we should see commercial LED efficacy pass the 200 lumens per watt mark. This level of efficiency, especially when compared to the 35 lumens per watt attained with incandescent bulbs, shows us that the future for solid state lighting is certainly bright…and efficient.
Sean Hawks is the Sales and Product Manager for enviroLED and member of IEC Rocky Mountain. He has spent his professional career working with construction trades of all sorts, especially in the electrical field where his experiences range from working with nuclear power plants and large utilities to his current position with enviroLED. enviroLED provides solid state lighting solutions for real world applications with a specialty in retrofit projects that will see a return on the investment in four years or less. Learn more at www.enviroLED.us.