George Craford, the father of AlInGaP and Solid State Lighting Fellow of Philips Lumileds talks about the technology’s future application and trends in an exclusive interview with LEDinside.

George Craford, Senior Fellow of Philips Lumileds. (LEDinside)

What are the biggest application markets for AlInGaP?

George Craford: Some of the biggest application markets for AlInGaP are architecture, automotive, and entertainment. We haven’t completely penetrated the automotive market yet, and have only achieved full penetration rate for stop lights. For illumination it would have to be a huge market, and in the signaling field the market for traffic lights is saturated. There is also a market for stadium signs, emergency markets and Emergency Vehicle Lighting (EVL).

What will be the main method and trend for generating white color in LEDs?

George Craford: In the LED market, the trend of using AlInGaP chip to create white color remains uncommon and only a small fraction of manufacturers are using this method. The simplest approach of generating white color in LEDs for mass production is still nitrade chip with phosphor. Technological difficulties of using an AlInGaP chip to produce white color include the chip’s different color temperature characteristics, different degradation rate, and reliability. Another issue with red phosphor is its wide color distribution might lower the lm/w ratio. However, AlInGaP chip’s are suitable for certain applications, such as in niche or high-end markets, and is expected to grow. While it is hard to say if there is a specific application for AlInGaP chips, a possible field is three color tunable LED, or applications that require high CRI, color LED, and higher lm/w. 

What is the future trend for smart lighting?

George Craford: I believe the smart lighting sector will grow. However, the color tuning market will probably remain small in the next 10 years, with a market share of less than 50%, as it depends on how widely these products are adopted by consumers.

Speaking of smart lighting can you talk about the technology behind Philips Hue bulbs?

George Craford: Philips Hue is still a novelty product. Its color change feature sets it apart from conventional lighting. LEDs always had the capacity to adjust colors. The product is not technically difficult to make, it uses a blue pump with red phosphor, and has a much more complex drive circuitry to add color control features. 

For color tuning technology, it would be better to develop a greener and more efficient green device. Green devices still are not as efficient as blue, and there is still what is technologically known as the green gap, in which green LED development has lagged behind blue. Ten years ago, I thought nitrade green can be developed in the same way as blue nitrades. Although, there are improvements in nitrade green, there were even more significant improvements in blue nitrade, the resulting graph still looks the same as it was a decade ago. 

Due to the human eye’s perception, green tends to be identified more easily than blue, but once the eye’s sensitivity peaks sensitivity for nitrade and green falls. There are just some things scientists cannot overcome as “Mother nature is still the boss.” Even if the green gap can be closed, there is still the question as to whether the resulting mix of bright red, blue and green will be overtly spiky and distort colors, such as a dress purchased from a shop, or the bathroom lighting might give a person a different appearance in the mirror. Consumers might not like the light even when the CRI might be good, the lighting color might not be broad enough, and current research points out a broad lighting is still more commonly accepted by consumers.

What are some future trends for LED applications in automobiles?

George Craford:There are a lot of red lights in automobiles, so AlInGaP applications are definitely expected to continually grow. It will definitely be a trend for both cars and traffic signals. AlInGaP can be applied in automobile lights that require red, orange and amber colors. We are currently developing a nitrade chip with amber chip that works better than amber phosphor.

For LED headlights we used nitrade and blue chip or phosphors to generate a white color. There will also be room for LED headlights to grow. LEDs are ideal for DRL applications, where the light is turned on at all times, since it can conserve energy. While I don’t have the exact figures, a research pointed out conventional lighting uses about 25% of a car’s power, while LEDs only use 10%. 

Legal restrictions regarding DRL or low/high beam lights will affect automotive LED developments. However, in principle LED headlight market is expected to grow. The price gap between LED and conventional head lamps is actually closing in, but LED lamps are slightly higher priced in general, and pricing will depend on lighting specification. Different legal regulations will affect how automotive LED lighting technology develops. Some country might choose automotive LED lights with dimming functions, while others will not.

Styling will also be a major application for automotive LEDs that will allow car makers to differentiate and give their cars notable features. When I delivered a speech to Detroit car makers in 1980s to adopt LED lighting it was very tough and most manufacturers were unconvinced. At the end of the speech I was approached by a stylist, who said that from a styling perspective of car differentiation, I was going to win the battle in the end, and he was right. LED DRLs can be energy efficient while providing distinctive car styles. 

Automotive lighting remains to be a very difficult market to get into, as car manufacturers tend to have very high requirements. It will also be difficult for Taiwanese manufacturers to enter DRL as their first step. Car manufacturers tend to place high emphasis on the lights reliability and quality, and this was a very difficult challenge in the early days.

Craford’s automotive LED lighting trend analysis echoes LED inside’s findings. From the OM equipment market, DRL will be the main drive behind LED automotive lighting growths from 2013-2015. LEDs penetration rate in the automotive lighting sector was a mere 5%, indicating there is still considerable room for growth. LED automotive lighting is projected to reach a CAGR of 26% in 2013-2017. On the other hand, the LED headlight market has continued its upward climb. As price gaps between conventional lighting and LED narrows, the lowered prices will also push up LED penetration rates in automotive lighting.