Materials for Solid State Lighting and Displays E-Book
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- Herausgeber: John Wiley & Sons
- Kategorie: Fachliteratur
- Serie: Wiley Series in Materials for Electronic & Optoelectronic Applications
- Sprache: Englisch
LEDs are in the midst of revolutionizing the lighting industry
- Up-to-date and comprehensive coverage of light-emitting materials and devices used in solid state lighting and displays
- Presents the fundamental principles underlying luminescence
- Includes inorganic and organic materials and devices
- LEDs offer high efficiency, long life and mercury free lighting solutions
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Seitenzahl: 720
Veröffentlichungsjahr: 2016
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Table of Contents
Cover
Title Page
Copyright
List of Contributors
Series Preface
Preface
Acknowledgments
About the Editor
Chapter 1: Principles of Solid State Luminescence
1.1 Introduction to Radiation from an Accelerating Charge
1.2 Radiation from an Oscillating Dipole
1.3 Quantum Description of an Electron during a Radiation Event
1.4 The Exciton
1.5 Two-Electron Atoms
1.6 Molecular Excitons
1.7 Band-to-Band Transitions
1.8 Photometric Units
1.9 The Light Emitting Diode
References
Chapter 2: Quantum Dots for Displays and Solid State Lighting
2.1 Introduction
2.2 Nanostructured Materials
2.3 Quantum Dots
2.4 Relaxation Process of Excitons
2.5 Blinking Effect
2.6 Surface Passivation
2.7 Synthesis Processes
2.8 Optical Properties and Applications
2.9 Perspective
Acknowledgments
References
Chapter 3: Color Conversion Phosphors for Light Emitting Diodes
3.1 Introduction
3.2 Disadvantages of Using LEDs Without Color Conversion Phosphors
3.3 Phosphors for Converting the Color of Light Emitted by LEDs
3.4 Survey of the Synthesis and Properties of Some Currently Available Color Conversion Phosphors
3.5 Multi-Phosphor pcLEDs
3.6 Quantum Dots
3.7 Laser Diodes
3.8 Conclusions
Acknowledgments
References
Chapter 4: Nitride and Oxynitride Phosphors for Light Emitting Diodes
4.1 Introduction
4.2 Synthesis of Nitride and Oxynitride Phosphors
4.3 Photoluminescence Properties of Nitride and Oxynitride Phosphors
4.4 Emerging Nitride Phosphors and Their Synthesis
4.5 Applications of Nitride Phosphors
References
Chapter 5: Organic Light Emitting Device Materials for Displays
5.1 Introduction to OLEDs and Organic Electroluminscent Materials
5.2 OLED Light Emitting Materials
5.3 OLED Displays
5.4 Quantum Dot Light Emitting Devices
References
Chapter 6: White-Light Emitting Materials for Organic Light-Emitting Diode-Based Displays and Lighting
6.1 Introduction
6.2 White Organic Light-Emitting Diodes
6.3 Photometry and Radiometry
6.4 Device Optics
6.5 Materials for Efficient White Electroluminescence
6.6 Polymer Concepts
6.7 Summary and Outlook
References
Chapter 7: Light Emitting Diode Materials and Devices
7.1 Introduction
7.2 Light Emitting Diode Basics
7.3 Material Systems
7.4 Packaging Technologies
7.5 Performance
References
Chapter 8: Alternating Current Thin Film and Powder Electroluminescence
8.1 Introduction
8.2 Background of TFEL
8.3 Theory of Operation
8.4 Electroluminescent Phosphors
8.5 Thin Film Double-Insulating EL Devices
8.6 Current Status of TFEL
8.7 Background of AC Powder EL
8.8 Mechanism of Light Emission in AC Powder EL
8.9 Electroluminescence Characteristics of AC Powder EL Materials
8.10 Emission Spectra of AC Powder EL
8.11 Luminance Degradation
8.12 Moisture and Operating Environment
8.13 Current Status and Limitations of Powder EL
8.14 Research Directions in AC Powder EL and TFEL
References
Index
End User License Agreement
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Guide
cover
Table of Contents
Preface
Begin Reading
List of Illustrations
Chapter 1: Principles of Solid State Luminescence
Figure 1.1 Lines of electric field produced by stationary point charge
Figure 1.2 Closed lines of magnetic field due to a point charge moving with constant velocity into the page
Figure 1.3 Lines of electric field emanating from an accelerating charge
Figure 1.4 Direction of magnetic field that is perpendicular to both the direction of acceleration as well as to from Figure 1.3
Figure 1.5 A time-dependent plot of coefficients and is consistent with the time evolution of wavefunctions and . At . Next a superposition state is formed during the transition such that . Finally, after the transition is complete
Figure 1.6 The exciton forms a. series of closely spaced hydrogen-Iike energy levels that extend inside the energy gap of a semiconductor. If an electron falls into the lowest energy state of the exciton corresponding to n = 1 then the remaining energy available for a photon is
Figure 1.7 Low-temperature transmission as a function of photon energy tor . The absorption of photons is caused through excitons, which are excited into higher energy levels as the absorption process takes place. is a semiconductor with a bandgap of 2.17 eV. Reprinted from Kittel, C., Introduction to Solid State Physics, 6e, ISBN 0-471-87474-4. Copyright (1986) John Wiley and Sons, Australia
Figure 1.8 A depiction of the symmetric and antisymmetric wavefunctions and spatial density functions of a two-electron system. (a) Singlet state with electrons closer to each other on average. (b) Triplet state with electrons further apart on average
Figure 1.9 Energy level diagram showing a ground state and excited singlet and triplet states. The excited triplet state is slightly lower in energy compared with the excited singlet state because two triplet state electrons are, on average, further apart than two singlet state electrons. Radiative emission from an electron in the excited singlet state to the ground singlet state is dipole-allowed. Radiative emission between the excited triplet state and the ground state requires an additional angular momentum exchange. See Section 1.6
Figure 1.10 (a) Parabolic conduction and valence bands in a direct-gap semiconductor showing two possible transitions. (b) Two ranges of energies in the valence band and in the conduction band determine the photon emission rate in a small energy range about a specific transition energy. Note that the two broken vertical lines in (b) show that the range of transition energies at is the sum of and
Figure 1.11 Photon emission rate as a function of energy for a direct gap transition of an LED. Note that at low energies the emission drops off due to the decrease in the density of states term and at high energies the emission drops off due to the Boltzmann term exp(−E/kT)
Figure 1.12 Absorption edge for a direct gap semiconductor
Figure 1.13 The eye sensitivity function. The left scale is referenced to the peak of the human eye response at 555nm. The right scale is in units of luminous efficacy. International Commission on Illumination (Commission Internationale de l'Eclairage, or CIE), 1931 and 1978
Figure 1.14 Color space chromaticity diagram showing colors perceptible to the human eye. The center region of the diagram indicates a Planckian locus, which corresponds to the colors of emission from a blackbody source having temperatures from 1000 to 10 000 K. This locus includes the solar spectrum corresponding to a 5250 K blackbody. International Commission on Illumination (Commission Internationale de l'Eclairage, or CIE), 1931
Figure 1.15 Eight standard color samples used to determine the colour rendering index
Figure 1.16 Band diagram of a p-n junction in equilibrium showing hole and electron currents. The net current is zero. is the built-in potential of the junction
Figure 1.17 Band diagram of p-n junction with positive bias voltage applied. The junction potential is decreased and a net diffusion current flows
Figure 1.18 Band diagram of p-n junction with negative bias voltage applied. The junction potential is increased and a net drift current flows
Figure 1.19 Resulting current–voltage characteristic of a diode showing an approximately exponentially increasing forward current and a saturated reverse bias current
Chapter 2: Quantum Dots for Displays and Solid State Lighting
Figure 2.1 Schematic band-energy diagrams for (a) direct band gap and (b) indirect band gap semiconductors
Figure 2.2 Schematic illustrations of (a) photoluminescence, (b) electroluminescence, and (c) cathodoluminescence
Figure 2.3 Schematic illustration of the changes of the density of quantum states with changes in the number of atoms in materials (see text for a detailed explanation)
Figure 2.4 CdSe QDs exhibited direct and indirect band gaps at atmospheric and ∼9.3GPa pressures. Arrows indicate the band gaps of the bulk CdSe at atmospheric pressure and 9 GPa, respectively.
Figure 2.5 Experimentally and theoretically determined band gap as a function of size of CdS QDs. Broken line: calculated parameters based on effective mass approximation; solid line: tight-bonding calculation; squares: experimental data.
Figure 2.6 A few radiative and nonradiative processes that can occur during luminescence. (a) Band edge recombination, (b) defect recombination, and (c) Auger recombination
Figure 2.7 Schematic diagram of (a) fluorescence (f) and (b) phosphorescence (p); hv is energy, and T and t are time. See reference [29] for detailed discussions.
Figure 2.8 Spectral absorption and photoluminescence profile depicting the Stokes shift
Figure 2.9 Blinking effect from a single 2.9nm CdSe QD. (a–c) Emission is shown in three expanded time scales.
Figure 2.10 Schematic illustration of (a) an organically capped QD and (b) an inorganically passivated QD (core/shell structure of QD). (c) An energy diagram shows the band-gap difference of core and shell of inorganically passivated QDs
Figure 2.11 Simulated color gamut coverage as full width at half maximum (FWHM) of QDs narrows from 60 to 20nm. Monochromatic primaries (FWHM = 0nm) representing the Rec. 2020 specifications are plotted as well. The peak wavelength of the simulated emission is the same as those of the Rec. 2020 primaries: 467nm, 532nm, and 630nm. The CIE color space coverage increases with decreasing QD FWHM. The simulations assume a Gaussian emission profile from the QDs
Figure 2.12 Comparison of color emission spectra, color filter effect, final LCD emission spectra in the liquid crystal module (LCM), and color gamuts with a white LED BLU (blue LED + YAG:Ce) and blue BLU (blue LED + QD film). By replacing the white BLU with a blue LED + QD combination, the color gamut is greatly enhanced.
Figure 2.13 The PL intensity versus temperature relative to that at 25 °C for three different generations of red (top) and green (bottom) emitting QDs from QD Vision and for narrow-band red (top) and green (bottom) emitting phosphors based on data found in the technical literature (K
2
SiF
6
:Mn
4
+
or KSF; SrLiAl
3
N
4
:Eu; Sr
x
Ca
1
−x
AlSiN
3
:Eu or SCASN:Eu; CaS:Eu; β-SiAlON:Eu; SrGa
2
S
4
:Eu or SrGaS:Eu – for further details, see reference [78]). The solid state photoluminescence quantum yield at 25 °C (SS EQE at RT) is shown for the QDs. Approximate temperature ranges that downconversion materials experience in film, edge optic, and on-chip configurations are separated with vertical broken lines. Order-of-magnitude approximation of blue LED BLU optical excitation intensities are also shown.
Figure 2.14 Three- and two-dimensional representations of the three form factors for integrating QDs into displays from left to right: edge optic, film, and on-chip. The bottom row of images shows the individual components separated from the modules.
Figure 2.15 Exploded view (simplified) of an LCD module showing the replacement of the diffuser sheet with the QD enhancement film.
Figure 2.16 View of a typical LCD module where the BLU is a direct-lighting system containing an array of blue LEDs illuminating a QD-containing film. This direct-lit BLU enables HDR content display.
Figure 2.17 The two bottom-emission QLED device structures. The left stack is the “regular” structure and the right is the “inverted” structure
Figure 2.18 The champion color gamut of QLEDs as of spring 2016, produced by NanoPhotonica, Inc. NanoPhotonica's QLEDs produce 90% of the Rec. 2020 color gamut, as well as ∼170% of the NTSC 1987 color gamut (also called SMPTE “C”, where SMPTE is the Society of Motion Picture and Television Engineers).
Figure 2.19 A comparison of two methods of creating white QLEDs: mixing primary colors and tandem layer construction of primary colors.
Figure 2.20 The U.S. Department of Energy assessment of materials critical to renewable energy and their supply risk. Of critical importance are Eu and Y, which are nearly ubiquitous in rare-earth downconversion phosphors for solid state lighting and displays.
Figure 2.21 Schematics of the three methods for incorporating QDs or phosphors in the “on-chip” mode. (a) Distributed materials in the encapsulation resin, (b) deposition of materials directly on the LED die, and (c) deposition of the materials as a “remote” phosphor away from the die, but still within the packaging.
Figure 2.22 Near-infrared fluorescence image of a xenograft 4T1 tumor with uptake of 6PEG-functionalized Ag
2
S quantum dots. The uptake of the QDs by the tumor was monitored for 24h. (a–e) Near-infrared imaging of a time course of 6PEG-Ag
2
S QD uptake by the xenograft tumor. (f) White light photograph showing the tumor grafted on to the leg of the mouse.
Chapter 3: Color Conversion Phosphors for Light Emitting Diodes
Figure 3.1 Plot of the external quantum efficiency (EQE) of LEDs vs. emission wavelength. The data points for wavelengths have been fitted to a polynomial function (dotted curve), and the photopic eye response function, V(x), is shown for comparison. Data for points 1 and 2 were reported in 2004 by Nichia Chemical Co. and Cree, respectively; the other data have been reported by Philips Lumileds Lighting Company for high power LEDs @ 350 mA, and .
Figure 3.2 CIE chromaticity diagram showing color triangles based on some of the currently available LEDs
Figure 3.3 Highest literature values of internal quantum efficiencies as a function of emission wavelength
Figure 3.4 The excitation and emission spectra of . The hatched peak depicts an exciting emission from a blue LED emitting at 470nm. The match of the exciting blue radiation to the excitation band of the phosphor is excellent
Figure 3.5 CIE chromaticity diagram showing the position of the emission of phosphor (point 7) and the emission of a blue 470nm LED (point 1). The other points (points 2–6) are explained in the text. The continuous curved line in the center of the diagram is known as the Planckian, which is the locus of blackbody emitters
Figure 3.6 The emission spectra of (thin black line), , (gray line) and , (thick black line).
Figure 3.7 CIE color chromaticity diagram showing the position of the emission of phosphor (point 1), the emission of , (point 2) and of , (point 3). The emission of a blue 470nm LED is also shown (point 4). The solid line crossing the Planckian from point 3 to point 4 shows how a real white can now be generated from the blue LED and the , phosphor.
Figure 3.8 Plot of Ce activator concentration in YAG:Ce vs. luminous efficacy (470nm excitation)
Figure 3.9 Plot of Ce activator concentration in YAG:Ce vs. luminous efficacy (comparison of 470 and 430nm excitation)
Figure 3.10 Plot of firing temperature vs. luminous efficacy of YAG:Ce phosphors ( and excitation)
Figure 3.11 Plot of Ce activator concentration in YAG:Ce phosphors vs. luminous efficacy (extended down to lower Ce concentrations)
Figure 3.12 Percentage reflectance of YAG:Ce at 470nm as a function of Ce concentration (mol%) in YAG:Ce phosphors
Figure 3.13 Plot of Pr co-activator concentration in YAG:Ce, Pr phosphors vs. luminous efficacy. The Ce concentration was 2.4mol% in each case
Figure 3.14 Plots of luminous flux vs. wavelength for phosphors with x equal to (a) 1.00, (b) 0.75, (c) 0.50, (d) 0.25, and (e) 0.00. The Ce concentration was 2.45mol% and the excitation was centered on a wavelength of 470nm (seen in the Figure due to partial reflection by the phosphors)
Figure 3.15 Luminous efficacies of phosphors
Figure 3.16 Observed excitation spectra of phosphors when monitoring emission at 550nm. (a) , (b) , (c) , and (d)
Figure 3.17 Plot of luminous efficacy vs. temperature for YAG:Ce phosphors (–2.4mol %)
Figure 3.18 Plot of luminous efficacy vs. temperature for YAG:Ce phosphor (Ce 5.0mol%)
Figure 3.19 Excitation spectrum of with 470nm LED emission superimposed
Figure 3.20 Chromaticity diagram showing CIE coordinates of
Figure 3.21 Photoluminescent emission spectra of thiogallate phosphors . (a) , (b) , (c) , and (d)
Figure 3.22 Plot of luminous efficacy vs. temperature for phosphor
Chapter 4: Nitride and Oxynitride Phosphors for Light Emitting Diodes
Figure 4.1 Schematics of the nephelauxetic effect and crystal field splitting of or ions in a host
Figure 4.2 A gas pressure sintering furnace used for firing nitride phosphors
Figure 4.3 Photoluminescence spectra (a) and quantum efficiency as a function of excitation wavelength (b) of the AlN:Eu, Si blue phosphor.
Figure 4.4 (a) Elemental distribution mapping of Eu, Si, and Al, showing the stacking faults in AlN:Eu, Si. (b) Proposed layered structure of AlN:Eu, Si.
Figure 4.5 Layered structure of
Figure 4.6 Photoluminescence spectra (a) and quantum efficiency (b) of .
Figure 4.7 Photoluminescence spectra of with (a) and (b) .
Figure 4.8 (a) Standard crystal structure, viewed from the c-direction; (b) simulated structure, showing the location of in the channel along the c-axis; and (c) HAADF-STEM image, showing the presence of in the large voids parallel to the c-axis.
Figure 4.9 Photoluminescence spectra of .
Figure 4.10 (a) Photoluminescence spectra and (b) quantum efficiency of
Figure 4.11 Excitation and emission spectra of .
Figure 4.12 (a) A single particle and (b) excitation and emission spectra of .
Figure 4.13 Photoluminescence spectra (a) and quantum efficiency (b) of
Figure 4.14 (a) Typical photoluminescence spectra, (b) quantum efficiency of , and (c) color tuning in
Figure 4.15 (a) Photoluminescence spectra of with varying and (b) thermal quenching of (1 mol%).
Figure 4.16 Excitation (a) and emission (b) spectra of with varying Ce concentrations.
Figure 4.17 Excitation and emission spectra of (10 mol%). The emission spectrum was measured upon 355 nm excitation, and the excitation spectrum was monitored at 430 nm
Figure 4.18 Photoluminescence and diffuse reflectance spectra of .
Figure 4.19 Excitation and emission spectra of . The emission spectrum was measured upon 450 nm excitation, and the excitation spectrum was monitored at 580 nm
Figure 4.20 Excitation and emission spectra of , Li with an orthorhombic structure.
Figure 4.21 Excitation and emission spectra of . The emission spectrum was measured upon 450 nm excitation, and the excitation spectrum was monitored at 550 nm
Figure 4.22 Excitation and emission spectra of (a) , (b) , and (c) . (d) shows the difference between the excitation spectra of (b) and (c). The inset shows the samples with and without UV lamp irradiation at 254 and 365 nm.
Figure 4.24 (a) Excitation and (b) emission spectra of , Mg phosphors (, ). The emission spectrum was measured upon 445 nm excitation, and the excitation spectrum was monitored at 518 nm
Figure 4.25 (a) Photoluminescence spectra and (b) quantum efficiency of , .
Figure 4.26 Diffuse reflectance, excitation and emission spectra of .
Figure 4.27 (a) A single crystal and (b) excitation and emission spectra of .
Figure 4.28 Excitation and emission spectra of . The inset shows the phosphor under UV irradiation.
Figure 4.29 Electroluminescence spectrum of the one-phosphor-converted white LEDs using yellow phosphor.
Figure 4.30 Electroluminescence spectrum of multi-band white LEDs, showing extra-high color rendering index.
Figure 4.31 Electroluminescence spectra of LED backlights after filtering: (a) ; (b) ; and (c) their color gamut in CIE 1976.
Chapter 5: Organic Light Emitting Device Materials for Displays
Figure 5.1 (a) Schematic diagram of the physical construction of a single layer OLED. (b) Energy band diagram of the OLED. The arrows illustrate the different steps of the electroluminescence process described in the text. EL, electroluminescent
Figure 5.2 (a) Schematic diagram of the physical construction of a three-layer OLED. (b) Energy band diagram of the OLED. The arrows illustrate the different steps of the electroluminescence process described in the text
Figure 5.3 (a) Schematic diagram of a host–guest three-layer OLED. (b) and (c) Energy band diagrams of the OLED illustrating the two possible emission mechanisms referred to in the text, respectively: (i) the recombination of the electrons and holes directly on the guest molecules; and (ii) e–h recombination on the host followed by the transfer of excitons from the host to the guest
Figure 5.4 Metal chelates: (A) tris(8-hydroxyquinolinato)aluminum (); (B) bis(10-hydroxybenzo[h]quinolinato)beryllium ; (C) tris(5-hydroxyquinoxaline)aluminum (); (D) tris(4-hydroxy-1,5-naphthyridine)aluminum [12]
Figure 5.5 Polycyclic aromatic hydrocarbons: (A) benzene; (B) naphthalene; (C) anthracene; (D) tetracene (adapted from [22]); (E) fluorene; (F) acridine; (G) carbazole (adapted from [23]); (H) 9,10-bis(3'',5''-diphenylbiphenyl-4'-yl)anthracene (TAT) [22]; (I) 9,10-bis[4-(di-4-tert-butylphenylamino)styryl]anthracene (ATBTPA) [24]; (J) (ADN) (adapted from [24]); (K) (TBADN) (adapted from [24]); (L) 5,12-dimethoxy-6,11-bis(5-triisopropylsilylthienylethynyl)tetracene (TACN) [25]; (M) rubrene [24]; (N) N,N,N',N'-tetrakis-(3,4-dimethyl-phenyl)-anthracene-9,10-diamine (TmpAD) [26]
Figure 5.6 Aromatic polymers: (A) poly(p-phenylene) (PPP) [35]; (B) poly(p-phenylene vinylene) (PPV) [35]; (C) poly(9,9′-dioctylfluorene) (PFO) [35]; (D) poly(3,6-silafluorene-co-2,7-fluorene) (PSiFF) [36]; (E) poly(4,7-di-2-thienyl-2,1,3-benzothiadiazole-co-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-9,9-dioctylfluorene) (PFNBr-DBT) [37]
Figure 5.7 Host materials: (A) N,N'-dicarbazolyl-4,4'-biphenyl (CBP) [47]; (B) poly(vinylcarbazole) (PVK) [35]; (C) 1,3-bis(N-carbazolyl)benzene (mCP) [23]; (D) 2,6-bis(N-carbazolyl)pyridine (26mCPy) [23]
Figure 5.8 Fluorescent aromatic dyes: (A) 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (DCM) [9]; (B) 4-(dicyanomethylene)-2-methyl-6-(julolidin-4-ylvinyl)-4H-pyran (DCM2) [9]; (C) 4-(dicyanomethylene)-2-tert-butyl-6(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran (DCJTB) [9]; (D) 4-(dicyanomethylene)-2-tert-butyl-6(1,1,7,7-tetramethyljulolidyl-9-enyl)-chromene (RED2) (adapted from [9, 49]); (E) 5,10,15,20-tetraphenyl-21H,23H-porphine (TPP) [50]; (F) 3-(2-benzothiazolyl)-7-diethylaminocoumarin (C540) [51]; (G) 10-(2-benzothiazolyl)-1,3,3,7,7-pentamethyl-2,3,6,7-tetrahydro-1H,5H,11H-benzo[l]-pyrano[6,7,8-ij]-quinolizin-11-one (C545P) [52]; (H) 7-(diethylamino)-4-(methyl)-coumarin (C47) [51]
Figure 5.9 Phosphorescent dyes: (A) fac tris (2-phenylpyridine) iridium (lll) [60]; (B) bis(2-phenylpyridine) iridium(III) acetylacetonate [60]; (C) bis(2-(3,5-dimethylphenyl)-4-methylpyridine) iridium(III) (2,2,6,6-tetramethylheptane-3,5-diketonate) [60]; (D) tris(1-phenylisoquinolinato-C2,N)iridium(III) [47]; (E) bis[(4,6-difluorophenyl)-pyridinato-N,C2'] iridium(III) picolinate (FIrpic) [47]; (F) (2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphine) platinum(II) (PtOEP) [55]; (G) bis[3-trifluoromethyl-5-(2-pyridyl)-1,2-pyrazolato] platinum(II) (Pt-A) [65]; (H) [6-(1,3-dihydro-3-methyl-2H-imidazol-2-ylidene-)-4-tert-butyl-1,2-phenylene-]oxy[9-(4-tert-butyltpyridin-2-yl-κN)-9H-carbazole-1,2-diyl- ] platinum(II) (PtON7-dtb) [66]
Figure 5.10 Thermally activated delayed fluorescent molecules: (A) [1,2-bis(o-ditolylphosphino)benzene]Cu(I)Br ((dtpb)Cu(I)Br) [81]; (B) ,4,5,6-tetra(9H-carbazol-9-yl)isophthalonitrile (4CzIPN) [74]; (C) 2,4-bis{3-(9H-carbazol-9-yl)-9H-carbazol-9-yl}-6-phenyl-1,3,5-triazine (CC2TA) [82]; (D) 2,4,6-tri(4-(10H-phenoxazin-10H-yl)phenyl)-1,3,5-triazine (tri-PXZ-TRZ) [83]; (E) bis[4-(9,9-dimethyl-9,10-dihydroacridine)phenyl]sulfone (DMAC-DPS) [84]; (F) bis[4-(3,6-di-tert-butylcarbazole)phenyl]sulfone (DTC-DPS) [85]
Figure 5.11 Aggregate-induced emissive molecules: (A) silole (adapted from [94]); (B) tetraphenylethene (TPE) (adapted from[95]); (C) triarylamine (adapted from [95]); (D) cyanostilbene (adapted from [92]); (E) 2,5-bis(benzo[b]thiophen-5-yl)-1-methyl-1,3,4-triphenylsilole (5-BTMPS) [94]: (F) (E)-1-(4'-(2,2-diphenylvinyl)-[1,1'-biphenyl]-3-yl)-2-(3'-(1,2-diphenylvinyl)-[1,1'-biphenyl]-4-yl)-1H-phenanthro[9,10-d]imidazole (BTPE-PI) [96]; (G) N,N'-((4,7-dihydrobenzo[c][1, 2, 5]thiadiazole-4,7-diyl)bis(4,1-phenylene))bis(N-(4-(1,2,2-triphenylvinyl)phenyl)naphthalen-1-amine) (TNB) [95]
Figure 5.12 RGB color patterning approaches for OLED displays: (a) side-by-side RGB OLEDs; and (b) white OLEDs plus CFs
Figure 5.13 Schematic representation of a PMOLED display
Figure 5.14 Cross section view of OLEDs fabricated on a TFT substrate
Figure 5.15 Typical AMOLED display circuit with two TFTs and one capacitor. is the voltage of the power supply
Figure 5.16 Cross-sectional view of (a) bottom emitting device and (b) top emitting device
Figure 5.17 Schematic representation of the conventional color patterning technique using FMMs
Figure 5.18 A magnified view of an AMOLED with the PenTile layout
Figure 5.19 (a) Schematic illustration of the laser-patterned PI contact shadow RGB OLED fabrication process. (b) A magnified view of the fabricated RGB OLED panel. Source: Kajima et al. 2014 [107]. Reproduced with permission of AIP Publishing LLC
Figure 5.20 Schematic illustration of the LITI process steps
Figure 5.21 (a) Size-dependent emission of CdSe/ZnS core–shell quantum dots. The maximum emission wavelengths range from 443 to 655nm. Source: Han et al. 2001 [133]. Reproduced with permission Nature Publishing Group. (b) Electroluminescence (solid) and photoluminescence (dashed) spectra of QD-LED devices made with various CdSe/ZnS quantum dot compositions. In most cases the spectral width is very small (∼30nm). Source: Anikeeva et al. 2009 [134]. Reproduced with permission of American Chemical Society. (c) Electroluminescence spectra of FIrpic (blue), (green), and (red) OLEDs which have much larger spectral widths, comparatively. Source: Chang et al. 2015 [135]. Reproduced with permission of Royal Society of Chemistry
Figure 5.22 (a) Energy level diagram for a CdSe/CdS–PPV bilayer QD-LED. Electrons are injected from the Mg cathode and holes are injected from the ITO anode. The QD–PPV heterojunction acts as a barrier for hole injection into the QD layer and an electron injection barrier into the PPV. (b) Electroluminescence spectrum for a 10nm thick CdSe/CdS layer. The QD emission peak is located at 613nm and the shorter wavelength peaks arise from the PPV contribution. (c) The PPV component is minimized with increasing QD layer thickness. Source: Schlamp et al. 1997 [140]. Reproduced with permission of AIP Publishing LLC
Figure 5.23 (a) Current efficiency of conventional, sensitized, and sensitized-annealed CdSe/CdS QD-LEDs. (b) Device structure of the sensitized CdSe/CdS QD-LED. The inset Figure depicts the rod-shape QDs that were used in this work. Source: Zamani Ziboni et al. 2015 [168]. Reproduced with permission of American Chemical Society
Chapter 6: White-Light Emitting Materials for Organic Light-Emitting Diode-Based Displays and Lighting
Figure 6.1 (a) Simplified cross-section of a typical organic light-emitting diode (OLED). Here, the cathode is highly reflective, the anode transparent to allow for light emission through the glass substrate. (b) Photograph of a typical white OLED with an active area of about 2 cm by 2 cm
Figure 6.2 Energy band diagram of a typical multi-layer OLED. Holes (plus) and electrons (minus) are injected from the respective electrodes into the organic semiconductor materials, where they are transported on the material's transport levels, that is HOMO and LUMO, respectively, as indicated by the boxes. These charges form bound states in the emission layer, so-called excitons. The dashed vertical lines indicate the excitonic states available in the EML and adjacent blocking layers [i.e., electron (EBL) and hole (HBL) blocking layer, respectively]. HIL, Hole injection layer; HTL, hole transport layer; ETL. electron transport layer; and EIL, electron injection layer. Arrows marked with crosses indicate pathways for charges and electrons that should be suppressed.
Figure 6.3 Photoluminescence spectra of four different OLED emitter materials spanning the visible part of the electromagnetic spectrum. All materials belong to the class of organometallic complexes sporting an efficient phosphorescence channel that captures all excitons
Figure 6.4 Various types of OLED architectures for white-light emission. The top cross-section indicates the general layout of a typical OLED unit. (a) Vertically stacked OLEDs emitting various primary colors [typically red (R), green (G), and blue (B)] to mix to achieve white light. (b) Lateral stacking of RGB units. (c) Single OLED containing a white-light emitting material. (d) Blue OLED with a remote down-conversion layer. (e) Single OLED with multiple emitters in one EML. (e) Single OLED with multiple sub-EMLs containing different colors (RGB).
Figure 6.5 Schematic of a Lambertian emission pattern in comparison with other light sources
Figure 6.6 Photopic function V(λ) describing the sensitivity of the human eye to light
Figure 6.7 Color matching functions (a) and two-dimensional CIE 1931 color diagram (b). Every color can be described by two coordinates x and y. The warm white point A and the point E of equal energy are plotted. The black line represents the Planckian radiator and the gray ones are lines of equal correlated temperature
Figure 6.8 Section of the CIE 1931 diagram including the eight chromaticity quadrangles which define a white light source and their CCT. The Planck curve, and the color points A and E are included for better visualization
Figure 6.9 Molecular structure, ordinary (solid) and extraordinary (dashed) refractive indices (upper traces) and extinction coefficients (lower traces) of hole transporting α-NPD and electron transporting .
Figure 6.10 Effective radiative efficiency of emitter molecules embedded into an optical environment (e.g., cavity) as a function of the Purcell factor F
Figure 6.11 Cross section of a bottom-emitting OLED layer structure (ETL, electron transport layer; EML, emission layer; HTL, hole transport layer; ITO, indium tin oxide) radiating through the substrate. The spatial electric field distribution for TE and TM polarized components are depicted for 400, 500, and 600 nm, respectively. The substrate mode in comparison indicates a pronounced coupling to TM polarized light
Figure 6.12 Cross section of a bottom-emitting OLED, indicating waveguide and substrate losses due to total internal reflection and plasmonic absorption at the cathode interface. Attaching external structures to the substrate such as a half sphere or prism, substrate modes can be made accessible in the far-field.
Figure 6.13 Scheme illustrating the different possible internal quantum efficiencies that can be achieved under electroluminescence based on conventional fluorescent emitters (left) and organometallic phosphorescent emitters (right). With 75% triplet exciton generation, the internal efficiency of conventional fluorescence in OLEDs is limited to about 25%.
Figure 6.14 (a) Energy diagram of the relevant triplet state energies of an all-phosphorescent OLED. Here especially, the matrix materials (TCTA and DCzPPy) as well as the adjacent blocker or transport layer materials (3DTAPBP and BmPyPB) are important. For the two phosphorescent emitters used, that is FIrpic and PQ2Ir, energetic confinement is given. (b) Phosphorescent (photoluminescence) spectra of matrix and adjacent transport materials with their respective triplet energies indicated.
Figure 6.15 Energy level diagram of the emission layer of a highly efficient, all-phosphorescent white OLED. Boxes indicate the triplet energy to the left, solid and dashed lines the HOMO and LUMO values, respectively, to the right. The dashed box indicates the exciton generation zone. D and F refer to Dexter and Förster, respectively. k
i
represents various rates. BT, back-transfer; b-r, blue to red; b-g, blue to green.
Figure 6.16 (a) Chemical structures of different molecules showing combined monomeric and excimeric emission. (b) Electroluminescence (EL) spectra of all emitters for both a 5% diluted emitter system and a neat film (100%). Spectra are normalized to their integrated intensity.
Figure 6.17 CIE color coordinates of different OLEDs based on the single emitter PtL
2
Cl as dispersed into a matrix material at different concentration. Open white circle and star refer to the standard illuminants E and A, respectively. Additionally, the corresponding photographs of the OLEDs are shown.
Figure 6.18 (a) Qualitative term scheme of a thermally activated delayed fluorescence (TADF) emitter molecule. and denote the first excited singlet and triplet state, respectively. represents various rates. ISC, intersystem crossing; RISC, reverse ISC; r, radiative; nr, non-radiative; F, fluorescence; P, phosphorescence. indicates the singlet–triplet splitting. (b) Qualitative representation of how RISC and the fluorescence rate depend on the singlet–triplet splitting
Figure 6.19 (a) Absorption and photoluminescence of a highly efficient TADF emitter 4CzIPN based on carbazole donor and cyano acceptor groups centered around a benzene ring. (b) and (c) show the calculated (TD-DFT) orbital densities of HOMO and LUMO wave functions, respectively.
Figure 6.20 Scheme illustrating the molecular design rules that allow for efficient separation of HOMO and LUMO wave functions and thus small singlet–triplet splittings
Figure 6.21 Comparison of the excitonic mechanisms of (a) phosphorescence and (b) thermally activated delayed fluorescence (TADF). The schemes are drawn for equal emission state energies (gray shading). represents various rates. ISC, intersystem crossing; RISC, reverse ISC; r, radiative; nr, non-radiative; F, fluorescence; P, phosphorescence. indicates the singlet–triplet splitting and is the gap between respective singlet states of phosphorescent and TADF emitters. (c) Qualitative shapes of phosphorescence and TADF-type photoluminescence.
Figure 6.22 (a) Left: General scheme for thermally activated delayed fluorescence (TADF). Right: TADF paired with a fluorescent acceptor molecule giving rise to TADF assisted fluorescence (TAF). (b) Emission spectra of a TADF donor 4CzIPN-Me, and absorption and emission of a fluorescent acceptor molecule TBRb indicating substantial spectral overlap between donor emission and acceptor absorption needed for Förster resonant energy transfer.
Figure 6.23 Various types of concepts for white polymer-based OLEDs (white PLEDs). (a) Polymer matrix materials (gray) doped with small molecules (either of fluorescent or phosphorescent; filled symbols, different shade and shape indicate different emitters), (b) two or more light-emitting polymers blended as a bulk film, (c) a hetero-junction made of two light-emitting polymers, and (d) white-light emission based on multicomponent copolymers.
Figure 6.24 Working principle of a white-light emitting copolymer made of a blue-emitting polymer backbone decorated with green- and red- emitting side-chain chromophores. The blue-emitting backbone is a poly(fluorene-co-benzene) (PF), DPAN and MB-BT-ThTPA serve as the green (GMC) and red (RMC) model compound, respectively.
Figure 6.25 (a) Chemical structures of two different repeat units of polymer materials pCzBP and pAcBP showing thermally activated delayed fluorescence. The donor and acceptor units of these materials are situated along the polymeric backbone. (b) TD-DFT calculations for the smallest representative systems, that is (D-A-D)-D'-(D-A-D), showing the respective HOMO and LUMO orbitals and energies. D, donor; A, acceptor; D is carbazole for pCzBP and acridan for pAcBP; A is benzophenone.
Chapter 7: Light Emitting Diode Materials and Devices
Figure 7.1 (a) Simplified structure and (b) electrical schematic symbol for a light emitting diode
Figure 7.2 Illustration of various recombination pathways for charge carriers in a semiconductor
Figure 7.3 Energy-momentum diagram for (a) a direct and (b) an indirect bandgap semiconductor. For a direct bandgap semiconductor, charge carriers may radiatively recombine quickly. In an indirect bandgdap semiconductor, momentum transfer from the crystal lattice, or via impurities, is required for radiative recombination, which slows down the process
Figure 7.4 Cartoon illustrations of (a) homojunction, (b) double-heterojunction (DH), and (c) multiple-quantum-well (MQW) heterojunction LED structures. The DH structure is advantageous over the homojunction structure for its ability to confine charge carriers. The MQW structure is advantageous over the DH because it further improves carrier confinement, while also minimizing the required amount of active layer material, thus preventing light reabsorption by the active layer
Figure 7.5 Lowest energy bandgap vs. crystal in-plane atomic lattice spacing for Wurtzite (Ga,In)N and cubic (Al,Ga)As and (Al,Ga)InP material systems. The latter two are latticed matched to GaAs, and provide direct bandgap emission for near-infrared to red – (Al,Ga)As – and red to amber – (Al,Ga)InP. (Ga,In)N is grown lattice-locked to GaN, and undergoes strong compressive stress as InN mole fraction is increased. Practical performance for (Ga,In)N is achieved from the UV-A to the green
Figure 7.6 Normalized photoluminescence efficiency vs. etch pit density for several III–V materials. (Ga,In)N is an outlier, maintaining relatively high efficiency for defect densities that would quench emission in other materials
Figure 7.7 Equal-lumen emission spectra for two “white” reference illuminants: CIE-A, which approximates tungsten incandescence at a color temperature of 2856 K; and D-65, which approximates typical noon-day solar radiation at the earth, at a color temperature of 6504 K
Figure 7.8 Historical (center) and present-day (right, circa 2016) low-power, mid-power, and high-power packages typical for LEDs
Figure 7.9 Evolution of LED chip light extraction efficiency over the last 25 years for both (Al,Ga)InP and (Ga,In)N LEDs. These data are for chips that are emitting into an encapsulating medium, for example, epoxy or silicone
Figure 7.10 Selected chip architectures that have been successful in achieving high light extraction efficiencies: (a) shaped transparent-substrate (TS) (Al,Ga)InP LED; (b) patterned sapphire substrate (Ga,In)N LED with indium–tin–oxide (ITO) contacts; (c) thin-film flip-chip (Ga,In)N LED; and (d) shaped TS (Ga,In)N LED.
Figure 7.11 Best-reported LED external quantum efficiencies as a function of peak emission wavelength, at current densities of 35 A/cm
2
or greater, and at room temperature. In addition to primary (Ga,In)N and (Al,Ga)InP LED performance, full-conversion phosphor-converted (PC) LED performance for green and amber emission are indicated
Figure 7.12 Simulated emission spectra for the LEDs of Table 7.1
Figure 7.13 Color points in x–y chromaticity space for the LEDs of Table 7.1, which also determine the LEDs dominant wavelengths which are a projection of their color points from the CIE-E “equal energy” illuminant to the edge of the chromaticity space
Figure 7.14 Typical light output vs. current (L–I) characteristics for (Ga,In)N blue-emitting and (Al,Ga)InP deep-red-emitting LEDs. The sublinear behavior for the (Ga,In)N LED, sometimes termed efficiency “droop”, is due primarily to Auger recombination
Figure 7.15 White-emitting LED actual (shaded) and forecast (unshaded) performance as tracked by the US Department of Energy, for both “cool white” (i.e., greater than 4000 K) and “warm white” (i.e., less than 4000 K) emitters. Since about 2012, LED performance has exceeded that of all the conventional light sources in common use
Figure 7.16 White-emitting LED luminous efficacy as a function of correlated color temperature. Warm white LEDs are generally less efficacious than cool white LEDs, due to their need for more red lumens. The color rendering index for each data point is indicated
Figure 7.17 Emission spectra for the blue-pumped phosphor-converted white-emitting LEDs of Table 7.2, with their varying color temperatures and color rendering indices (CRIs)
Figure 7.18 Color points for the LEDs of Table 7.2 in x–y chromaticity space. Also shown are the color points for a primary blue-emitting LED as well as for phosphors most commonly used today for general illumination applications
Chapter 8: Alternating Current Thin Film and Powder Electroluminescence
Figure 8.1 (a) Thin film double-insulating-layer TFEL device structure showing sequence of layers deposited as thin films on a glass substrate. Typical materials used are:
Figure 8.2 Thick film ceramic dielectric EL device. The TFEL phosphor and front electrode are grown on a thick film laminate to form a robust EL device. This structure has the advantage of a thick dielectric layer that is far less sensitive to defects that thin film dielectric layers. As a result of the high dielectric constant of the dielectric layer, high charge injection levels may be reached that permit higher phosphor brightness. In addition, more efficient light out-coupling than for the structure of Figure 7.1 may be obtained
Figure 8.3 Ceramic sheet dielectric EL device showing self-supporting substrate design. Rear electrode may be a thin film metalization. Due to the brittle nature of the thin ceramic sheet, only small-area devices are practical. The barium titanate substrate is typically 200 μm thick
Figure 8.4 High dielectric constant BaTiO
3
spheres are sandwiched between upper and lower electrodes to form many individual TFEL devices that form a flexible sheet of light. BaTiO
3
spheres are coated with thin film interface layers and phosphor layer on the upper side and conductive electrode layers on both upper and lower sides
Figure 8.5 Energy band diagram of TFEL device showing electron trapping at phosphor/ dielectric interfaces (solid circles are occupied traps, hollow circles are empty traps), tunneling, impact excitation of activator, and re-trapping
Figure 8.6 Brightness–voltage characteristic of ZnS:Mn EL phosphor measured in a thin film device similar to that shown in Figure 8.1. Note that the drive frequency is 1000 Hz. The device exhibits a characteristic sharp threshold voltage near 160 V due to the critical electric field required for electron transport through the phosphor layer. The luminous efficiency is also shown.
Figure 8.7 Equivalent circuit of TFEL device showing insulator capacitance (note that this represents the series capacitance of both dielectric layers if two layers are present), the phosphor layer capacitance, and phosphor breakdown voltage represented as the zener diode turn-on voltage in reverse bias
Figure 8.8 Q–V relation for EL devices operating (a) below and (b) above the threshold voltage. Note the abrupt change in slope above the threshold voltage when avalanching in the phosphor layer occurs
Figure 8.9 Sawyer–Tower circuit showing the sense capacitor in series with the EL device. The sense capacitor is often chosen to be approximately 100 times larger than the EL device capacitance
Figure 8.10 Sawyer–Tower output trace showing the charge versus applied voltage relationship for an EL device. The charge is derived from the voltage across a sense capacitor according to and is plotted versus applied voltage
Figure 8.11 Self-healing due to aluminum evaporation around short circuit
Figure 8.12 Typical structure of AC powder EL device. The EL active phosphor layer consists of suitably doped ZnS powder with particle size of approximately embedded in a polymer binder with thickness not much more than the phosphor particle diameter. This phosphor layer is sandwiched between two electrodes, at least one of which is transparent, and is supported by a substrate usually made from a flexible plastic sheet. The dielectric layer is a composite material with a high average dielectric constant and is generally made by embedding small grain barium titanate powder within a polymer binder
Figure 8.13 Typical microscopic view of EL from ZnS:Cu, Cl particles. Double tails at threshold voltage and above the threshold voltage are illustrated [19]
Figure 8.14 Phosphor particles containing dark segregations and emitting spots. Source: Chen and Xiang 2008 [20]. Reproduced with permission of John Wiley and Sons
Figure 8.15 EL emission mechanism and schematic energy-band diagram of AC powder EL devices: (a) Cu
2-x
S needles [21]; and (b) energy-band diagram [19, 22]
Figure 8.16 Conducting needle embedded in insulator. A uniform electric field is applied parallel to the needle. Geometrical field intensification occurs at the ends.
Figure 8.17 Illustration of the basic principle of the field-emission model. (a) upon field application, electrons and holes are ejected from the opposite ends of the conducting inclusion, where the field is intensified, into the ZnS lattice and to the relevant traps. Holes are trapped after a short path. Electrons can travel further and are also trapped. (b) Upon field reversal, trapped electrons recombine with trapped holes causing light emission. Simultaneously, other electrons and holes are field-emitted on the opposite two sides of the conducting inclusion.
Figure 8.18 Energy levels and absorption transitions of ZnS:Cu, Al phosphor before excitation (a) and during excitation (b).
Figure 8.19 Typical luminance–voltage and efficiency–voltage characteristics of an AC powder EL device.
Figure 8.20 AC Powder EL spectra of several ZnS phosphor materials.
Figure 8.21 Typical luminance maintenance curve of AC powder EL device.
List of Tables
Chapter 1: Principles of Solid State Luminescence
Table 1.1 Possible spin states for a two-electron system
Chapter 2: Quantum Dots for Displays and Solid State Lighting
Table 2.1 Band gap and Bohr radii data for selected semiconductors
Table 2.2 List of the television products from around the world incorporating QDs as of March 2016. This Table shows the composition and form factor for each brand as well as if a product is available or a demonstration unit has been shown
Table 2.3 Comparison of the qualities of rare-earth-doped phosphors and quantum dots
Chapter 3: Color Conversion Phosphors for Light Emitting Diodes
Table 3.1 Luminous efficacies (LE) and quantum efficiencies (QE) for in-house synthesized YAG:Ce phosphors having different Ce concentrations, along with the values for a commercial sample
Table 3.2 Various M-Si-N phases that have been studied as host lattices for color conversion phosphors (where M = Mg, Ca, Sr, Ba, Ln, Y)
Table 3.3 Color conversion phosphors that can be excited by UV or blue LEDs
Chapter 4: Nitride and Oxynitride Phosphors for Light Emitting Diodes
Table 4.1 Examples of nitride phosphors synthesized using silicon diimide and metals
Table 4.2 Examples of nitride and oxynitride phosphors prepared by the gas reduction and nitridation method
Table 4.3 Raw materials and temperatures for synthesizing nitride phosphors by the carbothermal reduction and nitridation method
Table 4.4 Nitride phosphors prepared by the alloy nitridation method
Table 4.5 Crystal structure and photoluminescence properties of nitride phosphors
Table 4.6 Crystal structure and photoluminescence properties of Eu
2+
-doped oxynitride phosphors
Table 4.7 Crystal structure and photoluminescence of some Ce
3+
− doped nitride and oxynitride phosphors
Table 4.8 Optical properties of white LEDs using a single yellow nitride or oxynitride phosphor
Table 4.9 Optical properties of white LEDs using multi-phosphors
Table 4.10 Optical properties of phosphor-converted white LEDs for LCD backlights
Chapter 5: Organic Light Emitting Device Materials for Displays
Table 5.1 Comparison between an OLED display and an LCD
Table 5.2 A comparison of the highest performance QD-LEDs to date based on select characteristics
Chapter 6: White-Light Emitting Materials for Organic Light-Emitting Diode-Based Displays and Lighting
Table 6.1 Summary of radiometric quantities and photometric equivalents
Chapter 7: Light Emitting Diode Materials and Devices
Table 7.1 Typical performance characteristics for “colored” LEDs circa 2015
Table 7.2 Typical performance characteristics for white-emitting LEDs circa 2015
Chapter 8: Alternating Current Thin Film and Powder Electroluminescence
Table 8.1 Important sulfide and oxide EL phosphors showing their composition color, CIE coordinates and reported luminous efficiency. Note that in many cases a range of efficiency values is given, since various values are reported depending on the device structure and preparation conditions
Table 8.2 Dielectric properties of binary oxide dielectrics
Table 8.3 Dielectric properties of complex oxide dielectrics
Table 8.4 A set of powder phosphors known to exhibit AC powder EL
Wiley Series in Materials for Electronic and Optoelectronic Applications
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Published Titles
Bulk Crystal Growth of Electronic, Optical and Optoelectronic Materials, Edited by P. Capper
Properties of Group-IV, III-V and II-VI Semiconductors, S. Adachi
Charge Transport in Disordered Solids with Applications in Electronics, Edited by S. Baranovski
Optical Properties of Condensed Matter and Applications, Edited by J. Singh
Thin Film Solar Cells: Fabrication, Characterization, and Applications, Edited by J. Poortmans and V. Arkhipov
Dielectric Films for Advanced Microelectronics, Edited by M. R. Baklanov, M. Green, and K. Maex
Liquid Phase Epitaxy of Electronic, Optical and Optoelectronic Materials, Edited by P. Capper and M. Mauk
Molecular Electronics: From Principles to Practice, M. Petty
CVD Diamond for Electronic Devices and Sensors, Edited by R. S. Sussmann
Properties of Semiconductor Alloys: Group-IV, III-V, and II-VI Semiconductors, S. Adachi
Mercury Cadmium Telluride, Edited by P. Capper and J. Garland
Zinc Oxide Materials for Electronic and Optoelectronic Device Applications, Edited by C. Litton, D. C. Reynolds, and T. C. Collins
Lead-Free Solders: Materials Reliability for Electronics, Edited by K. N. Subramanian
Silicon Photonics: Fundamentals and Devices, M. Jamal Deen and P. K. Basu
Nanostructured and Subwavelength Waveguides: Fundamentals and Applications, M. Skorobogatiy
Photovoltaic Materials: From Crystalline Silicon to Third-Generation Approaches, G. Conibeer and A. Willoughby
Glancing Angle Deposition of Thin Films: Engineering the Nanoscale, Matthew M. Hawkeye, Michael T. Taschuk and Michael J. Brett
Spintronics for Next Generation Innovative Devices, Edited by Katsuaki Sato and Eiji Saitoh
Physical Properties of High-Temperature Superconductors, Rainer Wesche
Inorganic Glasses for Photonics, Animesh Jha
Amorphous Semiconductors: Structural, Optical and Electronic Properties, Koichi Shimakawa, Sandor Kugler and Kazuo Morigaki
Materials for Solid State Lighting and Displays
Edited by
Adrian Kitai
Departments of Engineering Physics and Materials Science and Engineering, McMaster University, Hamilton, Canada
This edition first published 2017
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List of Contributors
Hany Aziz
, Department of Electrical & Computer Engineering, University of Waterloo, Canada
Debasis Bera
, NanoPhotonica, Inc., USA and Department of Materials Science and Engineering, University of Florida, USA
Tyler Davidson-Hall
, Department of Electrical & Computer Engineering, University of Waterloo, Canada
George R. Fern
, Brunel University, London, UK
Paul H. Holloway
, NanoPhotonica, Inc., USA and Department of Materials Science & Engineering, University of Florida, USA
Yoshitaka Kajiyama
, Department of Electrical & Computer Engineering, University of Waterloo, Canada
Adrian Kitai
, Departments of Engineering Physics and Materials Science and Engineering, McMaster University, Hamilton, Canada
Michael R. Krames
, Arkesso, LLC, USA
Simone Lenk
, Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP) & Institute for Applied Physics, Technische Universität Dresden, Germany
Jesse R. Manders
, Nanosys, Inc., USA
Lei Qian
, NanoPhotonica, Inc., USA and Department of Materials Science and Engineering, University of Florida, USA
Sebastian Reineke
, Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP) & Institute for Applied Physics, Technische Universität Dresden, Germany
Jack Silver
, Brunel University, London, UK
Michael Thomschke
, Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP) & Institute for Applied Physics, Technische Universität Dresden, Germany
Le Wang
, College of Optical and Electronic Technology, China Jiliang University, China
Robert Withnall
(deceased), Brunel University, London, UK
Rong-Jun Xie
, National Institute for Materials Science (NIMS), Japan
Series Preface
Wiley Series in Materials for Electronic and Optoelectronic Applications
This book series is devoted to the rapidly developing class of materials used for electronic and optoelectronic applications. It is designed to provide much-needed information on the fundamental scientific principles of these materials, together with how these are employed in technological applications. The books are aimed at (postgraduate) students, researchers, and technologists, engaged in research, development, and the study of materials in electronics and photonics, and industrial scientists developing new materials, devices, and circuits for the electronic, optoelectronic, and communications industries.
The development of new electronic and optoelectronic materials depends not only on materials engineering at a practical level, but also on a clear understanding of the properties of materials, and the fundamental science behind these properties. It is the properties of a material that eventually determine its usefulness in an application. The series therefore also includes such titles as electrical conduction in solids, optical properties, thermal properties, and so on, all with applications and examples of materials in electronics and optoelectronics. The characterization of materials is also covered within the series in as much as it is impossible to develop new materials without the proper characterization of their structure and properties. Structure–property relationships have always been fundamentally and intrinsically important to materials science and engineering.
Materials science is well known for being one of the most interdisciplinary sciences. It is the interdisciplinary aspect of materials science that has led to many exciting discoveries, new materials, and new applications. It is not unusual to find scientists with a chemical engineering background working on materials projects with applications in electronics. In selecting titles for the series, we have tried to maintain the interdisciplinary aspect of the field, and hence its excitement to researchers in this field.
Arthur Willoughby Peter Capper Safa Kasap
Preface
Luminescent materials play a key role in a vast range of products from luminaires to televisions to cell phones. We cherish well-illuminated indoor and outdoor spaces. We take for granted a wide range of spectacular flat panel displays and are actively developing next generation flexible materials for flexible displays and lighting products as well as a wider range of colors and higher quantum efficiencies in both display and lighting markets.
The book begins with a very accessible treatment of the theory of luminescence. The first chapter is designed to target fundamental processes in inorganic semiconductors and other materials as well as in molecular solids. It also introduces the key metrics by which luminescence is measured and qualified.
Subsequent book chapters then present the key categories of materials and the solid state devices they enable. The topics being addressed include organic light emitting diodes, more accurately referred to as organic light emitting devices, inorganic light emitting diodes, quantum dot wavelength conversion materials, a wide range of important phosphor down-conversion materials and electroluminescent materials and devices.
Solid state luminescent materials are rapidly displacing more traditional luminescence processes in fluorescent and other gas-phase lamps in all but a few areas of application. This trend will continue due to the unprecedented power efficiency of solid state light emitters since global warming is a topic of international concern. The decreasing cost and increasing importance of a wide range of solid state luminescent materials and devices makes this book an essential resource for both industry and academia.
Adrian KitaiHamilton, Ontario, Canada
Acknowledgments
I would like to express my gratitude to the many people who contributed to this book. The significance of the chapter contributors is self-evident and their expertise in their respective areas of specialization is second to none.
My thanks also extend to my assistant Dylan Genuth-Okonwho has made a big impact on my workload. Finally, it has been a great pleasure working with the staff at Wiley including Rebecca Stubbs, Emma Strickland and Ramya Raghavan who collectively guided me through the process of getting this book off the ground and continued doing so throughout the many stages of bringing the book to completion.
About the Editor
Adrian Kitai is Professor in the Departments
