lucept’s 1,000th blog post: an interview with george craford

A very special piece for you today: To celebrate Lucept’s 1,000th post exploring the future of architectural lighting, let’s momentarily turn our gaze from the future to appreciate one of the most consequential innovations to impact not only lighting, but humanity in general: The development of LED technology.

I would like to share with you a delightful interview with George Craford, one of the pioneers who drove the development of LED semiconductor technology from its infancy — an innovator who has truly made a “dent in the universe.”

Craford was recently bestowed the prestigious honor of the Queen Elizabeth Prize for Engineering, along with esteemed industry colleagues Isamu Akasaki, Shuji Nakamura, Nick Holonyak Jr and Russell Dupuis.

It is nearly impossible to overstate the disruptive impact of LED technology: LEDs radically “dematerialized” both electric light sources and digital displays. Goodbye brass’n’glass light sources; goodbye hulking CRT monitors. Architectural lighting was totally revolutionized and its future is now effectively 100% LED. Nearly every modern digital device relies on LED backlighting (simply try to envision the staggering numbers of TVs, smartphones, laptops, computer monitors, car dashboards, etc.). LED technology enabled the wholesale creation of large format direct-view screen technology – which is quickly revolutionizing the relationship between digital content and the built environment. And all of those are poised for another sweeping wave of LED innovation – micro-LED displays.

Yet most importantly, LED technology has allowed designers to completely rethink how we treat light in our built environment: Every light source is now just some form of a digital pixel, conveying data to us in various formats, and those pixels can take any form factor we can dream of.

Transistors might have fundamentally created the virtual world, but it is through LEDs that we humans can connect the real world to the virtual. 50 years into the evolution of LED technology, we are seeing LEDs revolutionize our relationship with light & space & data – creating profound new possibilities for impacting the human experience.

Innovation is really, really hard: In my Q&A with George, I was curious as to how the early LED pioneers were able to succeed against staggeringly difficult odds of success. Enjoy!


Brad: When you started decades ago, the concept of solid state lighting must have seemed so radical as to be nearly impossible. What inspired you to even start researching solid state lighting? In the earliest days, how far into the future were you able to see or imagine the impact of your work?

George: I was inspired to work on LEDs in the 1960s at the University of Illinois following a demonstration by Nick Holonyak who demonstrated a bright red LED in a dewar of liquid nitrogen. LEDs seemed exciting and important, but I was certainly not thinking about general illumination. I took a job at Monsanto company to work on LEDs where the goal was to make the brightest LEDs in the world so we could be the leader and sell product for applications such as indicator lights. We started working on red LEDs similar to the LED that Holonyak had made. In 1971, we developed an improved technology that increased the efficiency by a factor of 10 and yielded the first yellow and orange LEDs, as well as improved red. Our marketing department told me that we should focus our efforts on making the red better and not worrying about other colors. They said that the customers just wanted better red with lower cost and didn’t care about additional colors. Fortunately, they did not insist on that and we kept working on the new technology. In the end the other colors turned out to be very important for many applications, primarily indoors. LEDs were still generally not efficient enough to compete outdoors in the sun. However, we were not looking far into the future. We were generally just trying to satisfy what our customers wanted in the near term in the worldwide competitive environment.

In 1990, my team at Hewlett Packard introduced another new technology that improved light output by an additional 10 to 100 times for red, red-orange, and amber LEDs. It was then clear that LEDs would replace incandescent for colored light applications such as automobile taillights, moving message panels, and traffic signals. We also began to think about the possibility of general illumination. Blue LEDs were not available, and without blue we could not make white. A number of laboratories were working on technology for blue LEDs, but the efficiencies were low, and the reliability was generally poor. There was not a clear path to a high-performance blue, although Akasaki in Japan had been making some progress with GaN materials for several years. In 1993, Nakamura working at Nichia introduced high-performance blue LEDs. It was then clear that LEDs had a chance to compete with conventional lighting in at least some low power applications. In the later 1990s it became clear to many of us that LEDs should dominate most, if not all, of the existing technologies for illumination applications.


Brad: My own career almost perfectly matched the LED revolution, and being part of an LED startup in the early days gave me a wonderful view as to the state of the art in the technology. One thing that shocked me was how various industry insiders didn’t want to believe in LEDs even late into the revolution — an almost “aggressive disbelief” of clear industry trends. How did you persevere through the inevitable naysayers? What would you recommend to other R&D leaders in various fields about getting their technologies to market?

George: The conversion to LEDs for general illumination is, of course, now well underway. There was initially some pushback from conventional lighting companies who were interested in protecting their existing businesses and factories. Generally speaking, it was not too severe. Philips saw what was happening and formed a partnership with Hewlett Packard to move LEDs into general illumination. LEDs have too many advantages in terms of efficiency and reliability, and it seems unlikely that conventional technology will survive in any significant applications. Full penetration by LEDs will take time. There are still issues with standardization and with compatibility with various types of drive circuitry and dimming circuitry. At this point there is essentially no question about LEDs completely replacing conventional illumination technologies. The only question is how fast it will happen.


Brad: LEDs have changed nearly every piece of electrical technology that we know. What is next for solid state lighting? Does it continue to dematerialize until it is just like a magical dust of light and data?

George: There is nothing on the horizon to replace solid-state technology for general illumination applications. As Nick Holonyak said long-ago, LEDs are the “ultimate lamp.” Solid-state lasers may replace LEDs for some applications requiring a very high intensity beam such as automobile headlights. OLEDs have and will continue to replace LEDs in some display applications. However, it seems likely that LEDs will be the dominant form of solid-state technology for most general illumination applications. Applications will continue to emerge, such as the use of LEDs in conjunction with solar cells to provide light in Third World countries. We will see LEDS used in horticulture to make it possible to grow plants in climates and in crowded city environments. Ultraviolet LEDs will be used in air and water purification, and multicolor LEDs will mimic the circadian cycle to make our living environments more productive and healthier. A number of companies are developing very high-density small LED arrays for use in watches and in Augmented Reality applications.

Conventional technology has dominated lighting for less than 150 years. Its domination is nearly over. There is nothing on the horizon to challenge solid-state lighting.