Like any new technology, LED lighting must demonstrate a compelling value to buyers before it begins to win sizeable market share from the incumbent technologies it will replace. Over the past decade, research and development have yielded impressive improvements in the cost, color performance, light output, efficacy, reliability, lifetime, and manufacturability of LED products. Looking at LED packages specifically, the cost in dollars per kilolumen ($/klm) has been declining rapidly since 2005 at a rate of around 20% per year. As a result, LED lighting products have become competitive in almost every lighting application, but there is still room for improvement.
Despite the rapid pace of its development, LED lighting has not yet come close to achieving its full potential. Significant work remains to be done to further improve performance and reduce costs.
LEDs are semiconductor devices that produce light when an electrical current flows through them. Optimizing efficiency in LED lighting will hinge on ongoing improvements to light-generating materials (LEDs and phosphors) and system integration. LED package prices have declined to the point where they are typically no longer the primary cost component. Now LED package and luminaire system integration improvements can have a larger impact on the cost of LED lighting. However, solving technical challenges at the LED can still have a big impact on cost and efficiency, and enable new lighting value and applications. One package-integration direction has been to increase light output from a given package size to decrease cost, while another has been to drive LED material at lower current densities and use lower-cost packaging materials.
There are still many fundamental technical challenges that need to be met in order to achieve DOE's cost and efficacy goals. For example, better green and red LEDs can reduce phosphor conversion losses and enable color control. And the process of down-conversion – whether with phosphors or quantum dots – offers room for improvement. The alternative approach for creating white light using color-mixed LEDs offers another path to high efficiency and the possibility of color tunability. In addition, work remains to be done in such areas as current efficiency droop, color shift, and system reliability, as well as in light distribution, dimming, thermal management, and driver and power supply performance. Luminaire cost, performance, and design flexibility can also be improved by reducing efficiency losses at higher temperature and drive current operation conditions. And continuing to expand the range of LED package diversity is critical for addressing an expanding variety of lighting applications.