Title page

Contents

Executive Summary 10

1. DOE Solid-State Lighting Program 25

1.1. Program Background 25

1.1.1. Program Mission and outcomes 26

1.2. DOE SSL Program Processes 26

1.2.1. Engagement 27

1.3. Range of Program Activities 28

1.3.1. Funding Opportunity Announcements 28

1.3.2. Pacific Northwest National Laboratory 28

1.3.3. Other R&D Mechanisms 29

1.3.4. Prizes 30

1.3.5. Analyses 32

1.4. Achievements & Impacts 33

1.4.1. DOE SSL Program Achievements 33

1.5. Energy, Climate, and Environmental Impacts 34

1.6. Manufacturing and Jobs 36

1.7. Science - Scientific Discoveries and Application Understanding 36

1.7.1. Optoelectronic Materials Science 36

1.7.2. Lighting Science 36

2. Lighting Energy and Technology Status 38

2.1. SSL Energy Savings Potential 38

2.2. Lighting Performance Status 42

2.3. LED Efficiency and Cost 45

2.3.1. Efficiency status and breakdown 45

2.3.2. LED Luminaire Performance Breakdown 48

2.3.3. Impact of Performance Variants 49

2.3.4. LED and Luminaire Pricing and Cost Breakdown 51

2.3.5. Diffuse Light Sources 58

2.4. Lighting-Building Integration status 60

2.4.1. Building Energy and Carbon Efficiency 60

2.4.2. Lighting System Integration into Buildings 62

2.4.3. Lighting and the Grid 65

2.4.4. Lighting Sustainability and Lifecycle 69

2.5. Public Investment 71

2.5.1. Equitable Lighting 72

2.5.2. Workforce Training and STEM pipeline 72

2.6. Productivity from Lighting 73

2.6.1. Light Stimulus and Physiological Responses 73

2.6.2. Productivity Benefits from Lighting 75

2.7. Lighting Application Efficiency 76

2.7.1. LAE Status 77

2.7.2. LAE Examples 77

2.8. Crosscutting R&D Opportunities for Lighting Technology 79

2.8.1. Germicidal Ultraviolet 79

2.8.2. Displays 80

2.8.3. Horticultural Lighting 80

2.8.4. Animal Responses to Light 81

3. R&D Priorities 83

3.1. R&D Priorities Organization 83

3.2. Platform Technology 84

3.2.1. LED Sources 84

3.2.2. OLED Sources 112

3.2.3. Optical Delivery Efficiency 120

3.2.4. Intensity Control 128

3.2.5. Spectral Efficiency 131

3.2.6. Lighting System Concepts and Demonstration 133

3.2.7. Advanced Manufacturing R&D 138

3.2.8. LAE Framework and Model Development 144

3.3. Lighting Science 146

3.3.1. Non-visual Physiological Responses 146

3.3.2. Flicker 149

3.3.3. Glare 150

3.4. Lighting Integration and Validation 151

3.4.1. Building Level Energy Savings Validation 152

3.4.2. Validation of Physiological Impacts 153

3.4.3. Safety Validation 153

3.4.4. Lighting Performance Feedback 153

4. Targets for Select R&D Priorities 155

4.1. Platform Technology R&D 156

4.1.1. LED Materials, Chips, and Packages 156

4.1.2. Luminaires and Lighting Systems 159

4.1.3. Lighting Manufacturing Technologies 161

4.2. Lighting Science R&D 163

4.3. Lighting Integration and Validation 165

5. Appendix 166

5.1. Ongoing R&D - Currently Funded Projects 166

5.1.1. FOA 166

5.1.2. SBIR 167

5.1.3. OLED Testing Opportunity 167

5.1.4. PNNL 167

5.2. New Frontiers R&D 170

5.2.1. Germicidal Ultraviolet 170

5.2.2. Displays 178

5.2.3. Horticultural Lighting 185

6. References 190

Table 2.1. U.S. LED forecasted stock results for the Current SSL Path Scenario. LED penetration is projected to reach 84% of all lighting installations... 39

Table 2.2. U.S. LED forecasted energy and carbon savings by scenario. If the market continues at the current pace, LED products are expected... 41

Table 2.3. LED Lighting performance metrics and normalized costs for three representative lighting applications - indoor commercial lighting,... 44

Table 2.4. PC- and CM-LED package historical and targeted efficacy levels 47

Table 2.5. Breakdown of LED luminaire efficiencies for three representative lighting applications - indoor, outdoor, and lamps. The PC-LED package... 48

Table 2.6. Summary of current LED package price and future performance projections. The LED performance projections are taken from Figure 2.5... 53

Table 2.7. Comparison of the performance parameters of OLED and LED flat panels 60

Table 2.8. Summary of Challenges and R&D Opportunities for Grid-Interactive Lighting 68

Table 3.1. Phosphor-converted (PC) and color-mixed (CM) LED package historical and targeted efficacy levels 87

Table 3.2. 2017 Installed Stock Penetration of Lighting Controls 128

Table 3.3. Number of parking lot lighting systems installed at NGLS Outdoor Living Laboratory at VTTI meeting operation criteria, relative to the... 130

Table 3.4. Driver performance parameters for a conventional two-stage driver with silicon MOSFETs and a single stage driver with SiC MOSFETs... 136

Table 4.1. Assumptions for wavelength and color as used in the task descriptions 155

Table 4.2. LED Material and Device Science 156

Table 4.3. Diffuse Light Source Materials and Devices 157

Table 4.4. Down-Converter Materials 158

Table 4.5. Luminaire Power and Functional Electronics 159

Table 4.6. Advanced Lighting Application Concepts 160

Table 4.7. Lighting Application Efficiency Framework 163

Table 4.8. Human Physiological Impacts of Light 164

Table 4.9. Lighting Integration and Validation R&D Opportunities 165

Table 5.1. SSL R&D Portfolio: Current Research Projects, August 2021 166

Table 5.2. General illumination and horticultural metrics 188

Figure 1.1. Schematic showing the DOE SSL R&D annual process cycle of collecting inputs and outputs. The SSL Program works every year to... 27

Figure 1.2. The LSTL at Pacific Northwest National Laboratory in Portland, Oregon 29

Figure 1.3. Philips' LED lamp offerings based on technology development for the L-Prize 30

Figure 1.4. Brad Koerner's award-winning design for a sustainable LED luminaire 31

Figure 1.5. The timing and prize pool of DOE's recently announced L-Prize competition 31

Figure 1.6. Student pictures and testimonials from the DOE SSL R&D Workshop 32

Figure 1.7. Facts and figures regarding the impact of the DOE's SSL Program for 2020. Annual energy saved per year is calculated from the... 34

Figure 2.1. DOE SSL Program Goal Scenario Energy Savings Forecast, 2017-2035. The Current SSL Path scenario is projected to save 5,781 TWh... 38

Figure 2.2. Evolution of the 90th percentile efficacy over the last decade of LED lamps and luminaires listed in based on web-scraped LED data... 42

Figure 2.3. A schematic diagram illustrating the key attributes of an ideal lighting solution for an occupant. These attributes move beyond just... 43

Figure 2.4. Comparison of lighting attribute trade-offs for three representative lighting applications - indoor troffer, outdoor area light, and... 45

Figure 2.5. Efficacies and efficiencies over time for white and colored commercial LED packages measured at 25°C and 35 A/cm² in put current... 47

Figure 2.6. Representative examples of LED packages from the four main platforms, including (from left) high-power ceramic-based LEDs, mid-power... 51

Figure 2.7. Price for high-power and mid-power warm-white and cool-white LED packages over time. The prices have come down rapidly over the... 52

Figure 2.8. Typical cost breakdowns for high-power and mid-power LED packages. The LED die represents the biggest cost contribution of the LED... 54

Figure 2.9. Typical cost breakdowns for COB LED packages. The assembly cost is a significant contribution of the COB cost due to the large number... 55

Figure 2.10. Comparison of cost breakdown for different lighting applications in 2019. The categories of LED lighting products include a troffer,... 57

Figure 2.11. Comparison of cost breakdown for a 6" downlight from 2014 to 2019. The relative cost of the LEDs has dropped dramatically while other... 58

Figure 2.12. Example of white OLED panels integrated into a linear light fixture 59

Figure 2.13. A rigid and flexible OLED light, respectively. The flexible light can be bent with a radius of curvature of 10 cm or higher 59

Figure 2.14. 2020 Electricity consumed to meet commercial end-use demand, based on the 2021 Annual Energy Outlook reference case. Numbers... 61

Figure 2.15. California "duck curve" showing the mismatch between electricity demand and renewable energy production, which leads to over... 65

Figure 2.16. Hourly Site Electricity Use for Residential (top) and Commercial (bottom) buildings 66

Figure 2.17. Example of a grid-connected, net metered building with solar photovoltaic array for on-site energy generation and lighting loads on a... 69

Figure 2.18. A life cycle assessment published in 2020 compared three contemporary LED lamps (products 1-3) with the LED lamp considered by... 70

Figure 2.19. LEDs color optimized for viewing of specific retail products such as food type. Off-Planckian color points allow for spectral designs that... 74

Figure 2.20. There is an untapped potential in energy savings that can be reached beyond improving SSL source efficiency. The first panel shows... 76

Figure 2.21. LED roadway lighting retrofit of HPS lights. Left image shows upward directed light and intensity non-uniformity on road surface. LED... 78

Figure 3.1. A multi-faceted approach by the DOE SSL Program for accelerating and achieving energy efficient lighting that supports health, productivity,... 84

Figure 3.2. Schematic of two main white LED architectures. (a) The PC-LED uses blue LEDs to pump yellow and red down-converters; (b) the CM-LED... 85

Figure 3.3. Typical simulated spectral power density for white-light LED package architectures. In both the PC-LED and CM-LED, the peak wavelengths... 85

Figure 3.4. Efficacies and efficiencies over time for white and colored commercial LED packages measured at 25°C and 35 A/cm2 input current... 86

Figure 3.5. Blue LED EQE vs. current density (left) and schematic of LED QW valence band (right). The shaded regions of the graph indicate the... 88

Figure 3.6. Spectral power densities of state-of-the-art commercial LEDs vs. wavelength. The dashed lines are guides to the eye, illustrating the... 88

Figure 3.7. External quantum efficiency of blue and green LEDs as a function of current density shows the earlier onset of drop for green LEDs 89

Figure 3.8. Schematic of the LED quantum well valence band in a blue LED (top) and a green LED (bottom) 89

Figure 3.9. (a) Comparison of carrier injection in planar section of the LED active region to that occurring at a V-pit defect. The V-pit defect allows... 91

Figure 3.10. (a) Energy band diagrams for AlGaInP LEDs for unstrained active region designs (left) and a tensile-strained barrier active region design... 92

Figure 3.11. Schematic of red LED device and the improved aspects of the chip leading to improved wall plug (power conversion) efficiency 93

Figure 3.12. (a) Energy band offsets as a function of emission wavelength for the AlGaInP and AlInP emitter systems. AlInP has a higher direct-indirect... 94

Figure 3.13. LED efficiency as function of junction temperature. The thermal droop is seen as the LED efficiency declines as junction temperature... 94

Figure 3.14. The internal quantum efficiency (IQE) and the hot/cold factor of AlGaInP LEDs decreases as the wavelength drops towards the amber... 95

Figure 3.15. The energy band gap as a function of lattice contacts for (a) II-IV-nitride alloys and boron-containing III-nitride alloys. These new alloys... 96

Figure 3.16. Computational materials discovery was used to create a stability map of inorganic ternary metal nitrides and identify promising new... 97

Figure 3.17. Power conversion efficiency vs. current density for a state-of-the-art LED and laser diode (LD) emitting at violet wavelengths.... 98

Figure 3.18. The peak (maximum) power conversion efficiency of blue laser diodes over time. The PCE has grown rapidly over the past decade... 99

Figure 3.19. (a) Image of a surface mount white laser-based illumination package and (b) a schematic showing the internal configuration of the laser... 100

Figure 3.20. (a) Schematic band diagram of a stacked active region LED with tunnel junctions illustrating the tunneling effect of carriers, and (b)... 101

Figure 3.21. (a) External quantum efficiency as a function of LED mesa size for AlGaInP LEDs grown on GaAs. The EQE reduces rapidly below 70μm... 103

Figure 3.22. LED device sidewall surface treatments using chemical treatment (KOH) and atomic-layer deposition (ALD) coatings help limit the... 104

Figure 3.23. Illustrations of new lighting schemes (a) and (b) using color tunable pixelated light sources to create different spectral power distributions... 105

Figure 3.24. Spectrum comparison of a 90 CRI PC-LED with conventional phosphors (blue), a 90 CRI PC-LED with a narrow-band red phosphor... 106

Figure 3.25. Light loss of phosphors in LED packages under high blue flux densities (left) and color shift under stressed operating conditions (right)... 106

Figure 3.26. Quantum efficiency (QE) improvements can be seen in KSF phosphor from improvements in synthesis and materials processing... 107

Figure 3.27. Spectrum comparison of a 90 CRI PC-LED with conventional phosphors (red), a 90 CRI PC-LED with a narrow-band red quantum dots... 108

Figure 3.28. Comparison of LED package performance characteristics with red phosphor, a hybrid QD-phosphor red down-converter (90 ppm Cd),... 108

Figure 3.29. Emission wavelength of CdSe QDs as a function of dot diameter. [100] As the diameter increases, the emission wavelength of the QD... 110

Figure 3.30. The quantum efficiency of a typical garnet phosphor (left) and nitride phosphor (right) are shown as a function of temperature and... 111

Figure 3.31. A typical structure used in the stack of organic materials for OLED lighting panels with six emitter units labeled PH R+G for phosphorescent... 112

Figure 3.32. Percolative transport of electrons and holes in an OLED stack, involving less than 5% of the molecules 114

Figure 3.33. Relative light output from a multi-layer stack with diluted hole- and electron-transport layers 115

Figure 3.34. Improvements between 1996 and 2019 in the external quantum efficiency and time for the luminance from ELQD devices to decay to... 116

Figure 3.35. The structure of a conformable OLED lighting panel made on ultra-thin glass. The organic layers are encapsulated to prevent the ingress... 117

Figure 3.36. Internal light extraction layer with nanocrystals to tailor the refractive index and larger particles to scatter light 117

Figure 3.37. Effect of internal scattering layer using index matching and scattering particles: (a) Increase in panel efficiency, (b) Reduction in color... 118

Figure 3.38. Particle free inks: (a) micro-structure; (b) comparison of conductivity of different forms of metal inks particle-free ink nanoparticle ink... 119

Figure 3.39. Reflectance of aluminum, gold, and silver 119

Figure 3.40. Example case study of how improved optical control in an automotive mirror light (a) can lead to better lighting performance at lower... 121

Figure 3.41. Illustrations of different approaches to optical control. A conventional static lens (a) is the traditional solution with a fixed beam angle... 122

Figure 3.42. Schematic illustration of a matrix of single beams, steered using (left) conventional technologies versus (right) advanced and physically... 122

Figure 3.43. A schematic of a controllable lens integrated in a directional lamp (top). The liquid crystal molecules in the lens are oriented with an... 123

Figure 3.44. The luminous emittance as a function of luminous efficacy for three different LED package styles. The smaller optical source size of the... 124

Figure 3.45. Comparison of the center beam candle power (in cd/lm) for a standard domed LED package to a flat lens high luminance LED package... 124

Figure 3.46. Silicon metasurfaces can be designed to act as beam deflectors and vortex beam generators through wavefront control 125

Figure 3.47. (a) Illustration of the Lambertian distribution of the standard LED structure and the directional emission of a resonant cavity LED... 126

Figure 3.48. Comparison of different generations of adaptive driving beam (ADB) headlights showing in the improving resolution with increasing... 127

Figure 3.49. Illustration of implementation of pixelated lighting source in luminaire fixtures (left) and the beam steering that can be attained by... 127

Figure 3.50. SPD for different technology types. SPD on left is for an incandescent lamp, middle is for a typical fluorescent, and right is for a cool... 131

Figure 3.51. Luminous efficacy of radiation can be determined by calculating the overlap of the emitted spectrum with the luminous efficiency... 132

Figure 3.52. Action spectra for humans and plants 132

Figure 3.53. Comparison of a 220 W LED driver with and without wideband gap components. The two-stage conventional LED driver employing... 135

Figure 3.54. LED driver topologies based on semiconductor component types illustrated as a function of power output 135

Figure 3.55. Luminaire schematic containing an LED driver with an embedded sensor package. A lightguide is utilized to provide sampling of the... 138

Figure 3.56. Images of 3-D-printed lighting fixtures. [160] [161] Custom optical distribution features of decorative luminaires can be achieved... 141

Figure 3.57. Deposition of droplets by UV print head onto substrate material (left-top). Droplets of polymer are allowed to "Flow" under surface... 141

Figure 3.58. Images of integrated roadway luminaires with fully printed, integrated circuitry with LED, driver, sensors, and antennas 142

Figure 3.59. Schematic of a novel digital printer approach the illustrates the features of a self-assembly scheme with the use of die-containing... 143

Figure 3.60. LAE conceptual framework is a tool to identify to balance considerations of light source efficiency, optical delivery efficiency, spectral... 145

Figure 3.61. Schematic illustration of the neuroanatomical underpinnings of physiological effects of light. The ipRGCs transmit environmental... 146

Figure 3.62. Circadian Disruption in laboratory and field settings. The left panel displays potential causes of disruption and how they might differ... 147

Figure 3.63. Ability of daylight to meet WELL building standard daytime recommendations of equivalent melanopic lux, vertically (EMLv) at all... 151

Figure 3.64. Potential energy savings from implementing a time-out option in a neonatal intensive care patient room. Graph shown by the number... 154

Figure 5.1. A survey of the external quantum efficiency of UV LEDs from researchers around the world. There is a steep efficiency drop off moving... 171

Figure 5.2. Typical elevation view showing GUV fixture placed above the room occupants for safety 172

Figure 5.3. GUV luminaires designs. (a) Schematic of UV radiation pattern for an open top luminaire and a louvered luminaire design. Images of... 173

Figure 5.4. Cross-section of a wall-mounted GUV luminaire showing the key elements, including a parabolic reflector to direct UV rays out at a... 173

Figure 5.5. The damage for a range of polymeric surfaces commonly found in healthcare facilities under UVC radiation is assessed using a variety... 174

Figure 5.6. The modern germicidal action spectrum developed from a study of bacteria by F. Gates is plotted (left) along with the action spectrum... 176

Figure 5.7. The action spectra for ACGIH UV hazard, CIE erythema, and CIE non-melanoma skin cancer (NMSC) are compared. This decreasing... 177

Figure 5.8. Layers in a basic liquid crystal display 178

Figure 5.9. Optical film stack cross-section of a direct-view display backlight 179

Figure 5.10. OLED display structure as used by Samsung and others 180

Figure 5.11. Wavelength distribution of a 6" blue LED wafer grown in a Veeco Epik 14x6" MOCVD reactor. The wafer shows~4nm distribution across... 181

Figure 5.12. Major types of micro-LED assembly and transfer processes 182

Figure 5.13. Schematic illustration of the micro-LED transfer onto a TFT backplane and the monolithic integration of a micro-LED array on a CMOS... 182

Figure 5.14. Comparison of different TFTs and their impact on speed and performance. The oxide (IGZO) TFT can provide smaller transistors and... 183

Figure 5.15. Schematic illustration of the assembly process of an RGB micro-LED display 183

Figure 5.16. Schematic illustration of the assembly process of a micro-LED display with patterned QDs (top). Cross-sectional view of the... 184

Figure 5.17. Comparison of the performance benefits of various display technologies. LCDs are the incumbent and have the dominant market share... 185

Figure 5.18. Image of Aerofarms, world's largest vertical farm in Newark, NJ, from Roger Buelow presentation 2019 DOE SSL R&D Workshop. The... 186

Figure 5.19. Plant action spectra associated with the primary classes of photosensitive molecules in plants 187

Figure 5.20. Micro-moles per second per watt of photosynthetic photons (400-700nm). At longer wavelengths (~red) there are more photons per... 187

Figure 5.21. LED photosynthetic photon efficacy measured at 25°C and 35 A/cm2 input current density. PPE for a typical PC-LED architecture with... 189