The US Department of Energy has issued this year's edition of its SSL roadmap, identifying for both LEDs and OLEDs the manufacturing issues most in need of addressing.
At 127 pages, the report Manufacturing Roadmap: Solid-State Lighting Research and Development is a veritable encyclopedia of the current state of the art in the making of solid-state lighting. Is is part of the DOE's program of support to SSL manufacturers, with the goal of driving down costs to spur adoption. The DOE's ultimate goal, of course, is reducing energy usage in the US.
We might summarize the report's conclusions as follows: SSL is still too expensive; manufacturing costs must come down at all levels; LED packaging is going to represent a big part of the reduction; color stability is not well understood and that has to change; and OLEDs face an uphill struggle on all fronts.
The report is informed by long and deep conversations with those making solid-state lighting, conversations that have been going on since the DOE's SSL manufacturing program began in 2009. The DOE convenes an SSL manufacturing R&D seminar each year; 2014's was held in May. Industry researchers and engineers told the DOE's contractors where the problems now lie, how much progress can be expected in the coming years, and where resources can be applied to make this possible.
Rather than try to distill the essence of such a large opus, I will cherry-pick a few tidbits here. Those in need of an overview might start with the coverage at LEDs Magazine.
The table below (see page 18 of the report) lists the principal companies at the top of the supply chain for solid-state lighting. The report also has a similar table for those lower down the supply chain: the suppliers of equipment and materials, from epitaxial growth to phosphors and encapsulation to test and inspection.
Proposed driver information
And there is similar detail for OLEDs.
The cost of an LED package is projected to drop by about 65% between now and 2020, and the bulk of the reduction will come from the packaging piece of LED manufacture. Now accounting for 61% of a finished LED's cost, packaging will fall to 54% of the smaller total cost by the end of this decade. Other components of the process -- substrate, epitaxy, and wafer processing -- will hold steady in the percentage of finished cost they represent. Phosphor will rise slightly by that metric, while also falling in absolute terms. (See pages 23-24.)
The report states that driver manufacture is not an issue at the same level that SSL manufacture is; the process is well understood and there are few costs to be wrung from it. But the DOE continues to press for standard labeling and documentation on drivers (as we have done here), so that luminaire manufacturers know with more certainty what they are getting and what they are not. Ultimately, such standards would raise the overall quality (and longevity) of SSL.
The sidebar lists the data and metrics that the DOE wants to ask driver makers to include as standard with their products (see page 59). Some of these data are already widely shared, such as power factor correction, harmonic distortion, and (to a lesser extent) dimmer compatibility. Others are rarely if ever provided, such as power overshoot, efficiency variance with temperature and load, and off-state power.
We've barely touched on the OLED picture here. I urge you to download the full report and study the sections of interest at your own convenience.
— Keith Dawson , Editor-in-Chief, All LED Lighting