Technology Spillovers in Solid State Lighting
Creators: name: Weinold, Michael
Publisher: name: ETH Zurich
Year: 2020
Subjects: innovation management
physics
solid state lighting
light emitting diodes
LED
cost model
sustainable development
consumer experience
Gallium Nitride (GaN)
lighting

description: The first commercial white light-emitting diodes (LEDs) were introduced in 1997. Since then, they have seen significant improvements in performance and decreases in cost. Despite the significance of the technology, the sources for improvements in performance and reductions in cost have not been thoroughly investigated. The role of technology spillovers, knowledge originating in other technologies, sectors or other scientific discipline, on these has not been studied at all. By investigating both, we hope to learn lessons for accelerating innovation in clean energy technologies for climate change mitigation.

Out of the metrics describing LED performance, we find that device sub-efficiencies allows us to directly quantify the effect of breakthroughs. We further identify metrics relevant to consumer experience in lighting. To identify technology spillovers we employ a multi-method approach including a systematic literature review of scientific publications, industry reports, technical periodicals, patents, as well as semi-structured expert interviews. 11 eminent experts from academia and industry were interviewed. To quantify the effect of spillovers on reductions in manufacturing cost, a bottom-up process step resolution manufacturing cost model was developed. To quantify the effect on performance improvements, a combined approach of systematic literature review and spectral efficiency performance simulations based on Python scripts was used.

We find that the overall efficiency of the highest performing warm white light-emitting diode packages has improved from η=5.8% in 2002 to η=38.7% in 2020. No single loss channel dominates the overall the efficiency. Instead, an ensemble of loss channels corresponding to different physical loss mechanisms contributes serially and cumulatively. We further find that light-emitting diodes today excel across consumer experience metrics. Any required range of color temperature and color rendering performance can be obtained by spectral engineering of the device. Results from our cost model show that the manufacturing cost for low-mid power devices manufactured at a US based idealized location has decreased from 1.11USD(2020) in 2002 to 0.05USD(2020) in 2020, a 95% decrease. This was found to be largely due to increases in wafer size.

Our research shows that technology spillovers affect all performance dimensions of LEDs. During the period 2002 to 2020, they were responsible for 8.5% of the improvements in the total efficiency of devices. They were responsible for ∼100% of the improvements in consumer experience metrics. Due to the proprietary nature of information on changes in the manufacturing process, their effect on manufacturing cost could not be determined. Out of the 7 identified spillovers, all but one were the result of a systematic search for external knowledge by researchers. 5 originated in basic research in academia. We find that spillovers are more likely to affect loss channels which are physically well understood.