“Solid-state lighting” Lighting – prerequisite of human civilization
500,000 years ago- first torch 70,000 years ago – first lamp (wick) 1,000 BC – the first candle
1772 - gas lighting Yablochkov candle (1876) 1784 Agrand lamp - Agrand lamp the first lamp relied on research (Lavoisier) 1826 -Limelight - solid-state lighting device 1876 – Yablochkov candle
1879 – Edison bulb Limelight Edison bulb (1879)
High Brightness LED Process Chain Keys for High Light Efficiencies
Metal Organic Package Vapor Phase Epitaxy Chip Technology
Heat dissipation Light extraction (l-conversion Epitaxy Light extraction + Stokes losses) Electr. losses Internal Q. efficiency Substrate
. . . Wall plug = int electr extr package . Front Emission of Today's Power LEDS
Sapphire-PowerLED Thinfilm Technology (generic) surface emitter volume emitter top and bottom contacts top or bottom contacts
> 97 % ~ 49 % top emission Side emission
Thinfilm technology has the best front emission, higher luminance and best scalability. ThinGaN: The Way to Improve Light Extraction
Thinfilm principle: Present actions: • prevent absorption in substr. highly reflecting mirror PowerThinGaN• low internal absorption LED structure: thin epi layers • prevent waveguiding optimize surface roughness 1mm textured surface contact
GaN QW ^ Mirror layer Solder layer Carrier substrate
PowerThinGaN; scematic side view PowerThinGaN top view
Light extraction of 75% is reached LED technology: solutions for white light
chromaticity diagram 1st approach: Muli-colour-LEDs:
0.9 520 0.8 InGaN 540 510 0.7
560 0.6 InGaAlP turnable colours within 500 the yellow triangle & white 0.5 580
0.4 2nd approach: conversion: Planck 600 E 0.3 620 490 + = 0.2
480 colour on demand blue „yellow„ „white“ 0.1 LED phosphorous light
0 460 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 Chip Level Conversion (CLC): Principle improved light conversion chip level conversion (CLC) layer
phosphor CLC ThinGaN CLC – LED package ThinGaN
excellent color homogeneity Blue chip die sorted “white” chips Yellow phosphor high luminance 400 500 600 700nm perfectly suitable for optical systems
Dispositivi Optoelettronici 2006-2007
Lumen (lm)
Unità di misura del flusso luminoso. Equivale al flusso luminoso emesso da una sorgente isotropica di intensità luminosa di 1 candela su un angolo solido di 1 steradiante
Una sorgente isotropica con intensità luminosa di 1 candela emette un flusso luminoso totale di 4 lumen Candela (cd)
Unità di misura dell’intensità luminosa
Una candela è pari all'intensità luminosa, in una data direzione, di una sorgente che emette una radiazione monocromatica di frequenza pari a 540 × 1012 hertz e di intensità radiante in quella direzione di 1/683 di watt per steradiante InGaN (Blue) Improvement Over Last 6 Years
35
int ~ 73% 30
@ 20 mA 25 ~ 75% ThinGaN extr 20 ATON ~ 33% Standard int 15 extr= 50%
10 Radiant Power Radiant @20mA [mW] int ~ 30% 5
extr= 25%
0
Dez. 98 Dez. 99 Dez. 00 Dez. 01 Dez. 02 Dez. 03 Dez. 04 Dez. 05 Dez. 06 Dez. 07 Dez. 300 µm – class ThinGaN in 5mm radial package Blue White
WPE (@ 440 nm) efficacy 70% 140 58% 140 60% 120 138 lm/W 51% @ 20 mA 120 50% 100 110 lm/W @ 20 mA 100 40% 80
80 [mW]
30% 60 e WPE [%] F 60
20% 40 [lm/W] efficacy ca 8000K 40 31,4 mW ca. 6500 K 10% 20 20 ca. 4800 K 0% 0 0 0 20 40 60 80 100 0 20 40 60 80 100 current density [A/cm2] current density [A/cm2] Latest achieved R&D record values Power Balance of a White Power LED (1W Dragon) with 1mm2 InGaN-Chip (today)
60-70 lm/W can be reached with white Power LEDs today!!! mW mW
1500 350 mA ; 3,2 V 1500
1400 1400
1300 1300
200 120 1200 1200
Elect. 50% [lm/W] 105lm/W extraction 100 Efficiency Lum. 1100 150 1100 67 lm/W Package 80
1000 Q.E. Intern.
Extrakc. Eff. Extrakc. 1000
Package Conversion 100
900 Conversion 60 900
Stokes
800 77% 40 800 50 75electrical lm 700 84% Heat 20 700
600 Lum. Lum. Flux white[lm] 380 0 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 0 780 600
500 0 350 700 1050 1400 500
400 Current [mA]
400 60%
300 300
75%
94% 75 lm
200 200
100 76% 23% 84% Light 100 0 0 Further brightness improvement: approaches
Increase current more lumens
1st approach: Constant chip size - increase current density more lumens but less efficiency
2nd approach: Constant current density - increase chip size more lumens but more costs
Further brightness improvement: increase current density
1mm x 1mm: 300 112lm/W 120 84lm/W Phi_v (lm)
with CLC efficiency (lm/W) efficacy(lm/W) 250 100 50%50%
200 80 White
205 lm - 150 60
Dragon (lm)
v 100 40
with lens F 94 lm R&D values; Dragon with lens 50 20
0 0 0 200 400 600 800 1000 1200 1400 1600 current (mA) lumen output saturates & efficacy drops with increased current reasons: non-linearity of IQE by 1) current density and 2) heating
Dispositivi Optoelettronici 2006-2007
Technology platform efficiency of light generation dependent on current density: 1 mm: 45,1 A/cm2 epitaxy characteristic 1,4 250 µm: 1,3 45,5 A/cm2 1,2 rectangular: 2 1,1 27,8 A/cm 1,0 0,9
efficiency [a.u.] efficiency 0,8 0,7 500 µm: 10 35 60 85 81,2 A/cm2 current density [A/cm2] 200 µm: 42,7 A/cm2 comparison rectangular standard : Up to 15 % brightness increase by reduced current density
Dispositivi Optoelettronici 2006-2007
High End Chip Performance (R&D) 55% 47% 40 60%
35 50% 30 standard chip size 40% 25
20 30%
V = 3,1V @ 20mA QE EXT f PE[mW] 15 26.2mW 20% 10 10% 5
0 0% 0 5 10 15 20 25 30 35
300 120 Operating current [mA] Phi_v (lm)
efficiency (lm/W) efficiency 250 100 84 lm/W
200 80
White White White
- - - 161 lm
150 60 (lm/W) power chip 1x1mm²
92,7 lm
(lm) (lm) (lm) (lm)
v v
v 100 40
F F F Vf=3,1V @ 350mA 50 20 Dragon with YAGaG volume Lowest Vf reported casting and spherical lens 0 0 For power devices 0 200 400 600 800 1000 1200 1400 1600 Current (mA)
Dispositivi Optoelettronici 2006-2007
Further brightness imrovement: approaches
Increase current more lumens
1st approach: increase current @ constant chip area challenges:
- improve heat management (decrease Rth of entire device) - improve linearity of IQE regarding current density
2nd approach: increase current @ constant current density increase chip area challenges: - decrease costs per chip area and package
Dispositivi Optoelettronici 2006-2007
Further brightness imrovement: increase chipSingle area emitter with 1170lm 10000 ThinGaN chips in OS packages achieved @ OSRAM at constant current density (50 A/cm2) (50 lm/W) (> 80 lm/W) 1000 (82 lm/W)
1400µm 6x 1000µm 100
1000µm
(White) [lm] (White)
v 500µm 4x 1000µm F 10 300µm 230µm 1 1,E+04 1,E+05 1,E+06 1,E+07 1,E+08 Active area (µm x µm) Coming soon: typ. 1000lm white light product Comparison of LEDs with conventional light sources
OSRAM-OS –LEDs: conventional light sources R&D-status @ j < 10 A/cm2 & realistic future products (< 2 years) @ j > 50 A/cm2 glow discharge
150 CLC-LED (typ.) @ 50 A/cm2 fluorescent 100 RGB-LED (typ.) 2 @ 50 A/cm halogen
50 electrooptical efficiency [lm/W] efficiency electrooptical 0 incandescent 1980 1990 2000 2010 2020 Roland Haitz‘s Battlefields for LED Lighting – and Our OSTAR Position
Flux/LampFlux/Package & Cost/Lumen & Cost/Lumen (Red & White) 1,E+05 OSTAR® White 1,E+04
1,E+03 Lighting Cost/Lumen ($/lm) 1,E+02 ) Flux/Lamp (lm) 1,E+01 Battlefields for Lighting 1,E+00 Red 1,E-01 -10x/Decade 1,E-02 +20x/Decade 1,E-03 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015 2020