organic light-emitting diodes · 2015-11-17 · organic light emitting diode lighting 3 • history...
TRANSCRIPT
ORGANIC LIGHT-EMITTING DIODES
LIGHTING TOWARD A SUSTAINABLE ENVIRONMENT
1
Angelo Angeles (HS Teacher) Dr. Reginald Eze (Mentor)
Dr. Yasser Hassebo (Mentor)
Colleen Cleary (Undergraduate) Leo Panish (HS Student)
Objective
2
ChangingtheparametersofasimulatedOLEDandanalyzingtheeffectsofthesechangeson
OLEDemissionpa=erns.
TheresultsofthisstudyprovideatemplateforapotenAalOLEDwithenhancedcolor-
brillianceandbrightness.
ORGANIC LIGHT EMITTING DIODE LIGHTING
3
• HistoryandApplicaAonsofOrganicLight-EmiHngDiodes
• OLEDsComparedtoOtherLightSources• WhatisanOrganicLight-EmiHngDiode?
• HowDoesitWork?
• WhyisittheNextGeneraAonofTechnology?
• IntroducAon
• Method• ResultsandConclusion
Light-Emitting Diode (LED) Anelectronicdevicethatemitslightwhenan
electricalcurrentisappliedtoit.
Organic Acompoundthatiscarbon-based.
4
What is an OLED?
What is an OLED?
Anarealightsourcethatcontainslayersofthin,flexiblesheetsoforganicelectroluminescentmaterial.
5
h=p://www.osadirect.com/staAc/img/news/img20130708lgchem01.jpg
6
h=p://assets.inhabitat.com/wp-content/blogs.dir/1/files/2011/09/UD-OLED2.jpg
What is an OLED?
Evolution of Light www.lightem
iHngdiodes.com
Incandescentlamp 17.5lm/W 0.9years
Linearfluorescentlamp 67-110lm/W 5.0yearsCompactfluorescentlamp 49-75lm/W 7.3years
Light-EmiHngDiode upto140lm/W13.7years
7
OrganicLight-EmiHngDiode 120lm/W36.5yearsLifespanfoundfromGE60Wbulbscalculatedfor3hrs/day
LifeAmeEfficiency
OLEDs vs. LEDs
• OLEDsareareasources• Smallenoughtobeusedas
pixelsinadisplay• Moderndisplayscanbeless
than1mmthickandweighlessthan4.5lbs
• Canbemadeflexible
• LEDsarepointsources• UsedtobacklightLCDTVs• Moderndisplayscanbeless
than1.5inchesthickandweighlessthan35lbs
• Encasedinepoxy(plasAccapsule)
8
h=p://www.noguge.com/thumbnail/l/led-lights-8.jpeg
h=ps://upload.wikimedia.org/wikipedia/commons/f/f2/OLED_EarlyProduct.JPG
• 1960:MarAnPopedevelopedatechniquetoconnectanelectriccurrenttoorganiccrystals.
• 1987:ChingW.TangandStevenVanSlykeatEastmanKodakreportedthefirstsmall-moleculeOLEDdevice.
History of OLEDs
9
h=p://i2.wp.com/www.stevehuffphoto.com/wp-content/uploads/2012/01/kodak-logo.jpgh=ps://upload.wikimedia.org/wikipedia/
commons/a/aa/MarAn_Pope.jpg
• 1950’s:AndréBernanoseobservedelectroluminescenceinorganicmaterials.
h=p://blog.virginiatoy.com/wp-content/uploads/2013/09/EDC-GlowsAcks.jpg
• In2003,KodakbeganintegraAngOLEDtechnologywiththeirdigitalcameras.
• In2007,SonyannouncedtheXEL-1,thefirstOLEDTV.
• In2015,LGunveiledtheworld'sthinnestOLEDTV.
Commercialization of OLEDs
10
h=p://cdn.itechnews.net/wp-content/uploads/2009/01/sony-bravia-xel-1-ultra-
slim-oled-tv.jpg
h=p://h=p://img.tomshardware.com/de/2003/08/08/
fotokuenstler_bis_5_megapixel_16_digitalkameras_im_fokus/kodak_d01.jpg
h=p://h=p://www.techbel3arabi.com/wp-content/uploads/2015/05/lg-wallpaper-tv.jpg
CATHODE
EMISSIVELAYER
CONDUCTIVELAYER
ANODE
SUBSTRATE
How does an OLED work? • PotenAaldifferenceis
appliedtothetwoelectrodes.
• Electronstravelfromcathodetoanode.
• Holesrecombinewiththeelectronsintheemissivelayer.
• Energyisreleasedaslightanddirectedtowardsthesubstrate.
11
ORGANIC LIGHT EMITTING DIODE LIGHTING
14
• HistoryandApplicaAonsofOrganicLight-EmiHngDiodes
• OLEDsComparedtoOtherLightSources• WhatisanOrganicLight-EmiHngDiode?
• HowDoesitWork?
• WhyisittheNextGeneraAonofTechnology?
• IntroducAon
• Method• ResultsandConclusion
Refractive Index
13
h=ps://d2jmvrsizmvf4x.cloudfront.net/if5aenByR5yU8Nm5WsXF_refracAon.jpg
HighIndex
LowIndex
• Propertyofmaterials
• Definedas𝑛= 𝑐/𝑣
• Usedtodeterminevaluessuchasincidentangleofthem↑𝑡ℎ layer
Adding Microcavities and DBRs
Producesstandingwavesusingphasechange
14
Createsstandingwavesthatamplifythelight
Microcavity
DBRh=ps://upload.wikimedia.org/wikipedia/commons/3/30/ParAal_transmi=ance.gif
HighIndexLowIndex
"MicrodisplaysBaseduponOrganicLight-emiHngDiodes."IBMJournalofResearchandDevelopment
Nine-Step Algorithm
15
OuterloopforIncidentangles(-90degrees<q<90degrees)
CalculaCngRefractedanglesandLayersthickness
InnerloopforWavelength(Braggwavelength+/-180)
CalculaCngtheOpCcaladmiMance
CompuCngtheTransmiOvityandReflecCvityvalues
CalculaCngPhasefactorandCharacterisCcMatrix
Graphs
Userinputvalues
ConverCngvaluesforcalculaCon
OLEDwithDBRs
𝐃𝐁𝐑↓𝐦 SU
BSTRATE
Highindex
HighindexLow
index
Lowindex
𝐃𝐁𝐑↓𝟏
HighindexLow
index
𝐃𝐁𝐑↓𝟐 ConducCve
LayerEm
issiveLayer
1.
2.
3.
4.
5.
6.
7.
8.
9.
FirstSimulaAon
Validity of Code
16
Liddell,HeatherMary.,andH.G.Jerrard."PeriodicMulAlayersandtheClassicalStack."Computer-aidedTechniquesfortheDesignofMulAlayerFilters.Bristol:A.Hilger,1981.14-18.Print.
Wavelength (nm)200 250 300 350 400 450 500 550
Refle
ctivit
y (%)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1Reflectivity vs Wavelength
1 Stack5 Stacks9 Stacks13 Stacks
Validity of Code
17
Approach
18
OLEDwithDBRsandamicrocavity
𝐃𝐁𝐑↓𝐦
SUBSTRATEHighindex
HighindexLow
index
Lowindex
𝐃𝐁𝐑↓𝟏
HighindexLow
index
𝐃𝐁𝐑↓𝟐 ConducCve
LayerMicrocavity
HighindexLow
index
𝐃𝐁𝐑↓𝐦
−𝟏
EmissiveLayer
Wavelength (nm)150 200 250 300 350 400 450 500 550
Ref
lect
ivity
(%)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1Reflectivity vs Wavelength
Wavelength (nm)150 200 250 300 350 400 450 500 550
Tran
smis
sion
(%)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1Transmission vs Wavelength
FinalSimulaAon
Approach
19
• Goals:
Wavelength (nm)150 200 250 300 350 400 450 500 550
Ref
lect
ivity
(%)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1Reflectivity vs Wavelength
Wavelength (nm)150 200 250 300 350 400 450 500 550
Tran
smis
sion
(%)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1Transmission vs Wavelength
• Parametricstudy
1. MaximumtransmissionatBraggwavelength
2. MaximumreflecAonatsurroundingwavelengths
• Focusonsmallbandwidth
• 𝑅+𝑇=1
ORGANIC LIGHT EMITTING DIODE LIGHTING
22
• HistoryandApplicaAonsofOrganicLight-EmiHngDiodes
• OLEDsComparedtoOtherLightSources• WhatisanOrganicLight-EmiHngDiode?
• HowDoesitWork?
• WhyisittheNextGeneraAonofTechnology?
• IntroducAon
• Method• ResultsandConclusion
Results
21
Wavelength (nm)100 200 300 400 500 600
Ref
lect
ivity
(%)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1Reflectivity vs Wavelength
ChangingthenumberofDBRstacksaboveandbelowthecavityaffectstransmission.
Wavelength (nm)150 200 250 300 350 400 450 500 550
Ref
lect
ivity
(%)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1Reflectivity vs Wavelength
Before After
UnequalStacks EqualStacks
Wavelength (nm)150 200 250 300 350 400 450 500 550
Ref
lect
ivity
(%)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1Reflectivity vs Wavelength
Wavelength (nm)150 200 250 300 350 400 450 500 550
Ref
lect
ivity
(%)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1Reflectivity vs Wavelength
Results
22
Changingthesubstrateindexaffectsmaximumtransmission.
Before After
HighIndex LowIndex
Wavelength (nm)150 200 250 300 350 400 450 500 550
Ref
lect
ivity
(%)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1Reflectivity vs Wavelength
Results
23
ChangingthecavityindexaffectsreflecAonpa=erns.
Wavelength (nm)150 200 250 300 350 400 450 500 550
Ref
lect
ivity
(%)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1Reflectivity vs Wavelength
Before After
FarfromInteger ClosetoInteger
Wavelength (nm)150 200 250 300 350 400 450 500 550
Ref
lect
ivity
(%)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1Reflectivity vs Wavelength
Wavelength (nm)150 200 250 300 350 400 450 500 550
Ref
lect
ivity
(%)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1Reflectivity vs Wavelength
Results
24
ChangingthelengthofthemicrocavityaffectstransmissionattheBraggwavelength.
Before After
1/8 Braggwavelength 1/2 BraggWavelength
EqualDBRstacksaboveandbelowcavity.
SubstraterefracAveindexcloseto1.0(vacuum).
CavityrefracAveindexclosetointeger.
Cavitylengthof1/2 or 1/4 theBraggwavelength.
Conclusion
25
Wavelength (nm)150 200 250 300 350 400 450 500 550
Refle
ctivi
ty (%
)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1Reflectivity vs Wavelength
Wavelength (nm)150 200 250 300 350 400 450 500 550
Tran
smiss
ion
(%)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1Transmission vs Wavelength
1.
2.
3.
4.
Final ForMaximumTransmission:
ORGANIC LIGHT EMITTING DIODE LIGHTING
28
• HistoryandApplicaAonsofOrganicLight-EmiHngDiodes
• OLEDsComparedtoOtherLightSources• WhatisanOrganicLight-EmiHngDiode?
• HowDoesitWork?
• WhyisittheNextGeneraAonofTechnology?
• IntroducAon
• Method• ResultsandConclusion
Organic Light-Emitting DiodesADVANTAGE
S • Energyefficient• Environmentallyfriendly• DoesnotemitheatorUV
rays• Closestlightsourceto
naturallight• Thinnerandlighterthan
otherlightsources• Costdecreasepredictedto
occurinthenext5years• Canbeproducedaslarge
sheets• Truerblacksandbe=er
contrastondisplays27
• EfficiencyissAlllowcomparedtoLEDefficiency
• BlueOLEDlifeAmeismuchshorterthantheredandgreen
• Thecosttomanufactureiscurrentlyexpensive
• SensiAvetowaterandUVrays
DISADVANTAGES
Potential OLED Applications
hMp://www.demilked.com/magazine/wp-content/uploads/2014/10/windowless-passenger-plane-oled-touchscreen-walls-cpi-6.jpg
h=p://www.ledsmagazine.com/content/dam/leds/migrated/objects/news/6/7/10/GECIA_Clothes.jpg
h=p://www.superimaging.com/img/hud1.jpg
28
Sources 1. Heavens,O.S.OpAcalProperAesofThinSolidFilms.London:Bu=erworthsScienAficPublicaAons,
1955.Print.2. Geffroy,Bernard,PhilippeLeRoy,andChristophePrat."OrganicLight-emiHngDiode(OLED)
Technology:Materials,DevicesandDisplayTechnologies."Polym.Int.PolymerInterna.onal55.6(2006):572-82.Print.
3. Kalyani,N.Thejo,andS.j.Dhoble."OrganicLightEmiHngDiodes:EnergySavingLighAngTechnology—AReview."RenewableandSustainableEnergyReviews16(2012):2696-723.Print
4. "OLEDTechnology:IntroducAonandBasics."OLEDTechnology:Introduc.onandBasics.Web.6July2015.
5. Howard,W.E.,andO.F.Prache."MicrodisplaysBaseduponOrganicLight-emiHngDiodes."IBMJournalofResearchandDevelopmentIBMJ.Res.&Dev.(2001):115-27.Print.
6. Burroughes,J.H."Light-emiHngDiodesBasedonConjugatedPolymers."Nature347(1990):352.Print7. Antoniadis,Homer,Ph.D."OverviewofOLEDDisplayTechnology."OsramOpAcalSemiconductors.
h=p://www.ewh.ieee.org/soc/cpmt/presentaAons/cpmt0401a.pdf8. "DuPontshowsnewAMOLEDmaterialsandOLEDdisplays"OLED-Info.com.9. Howard,WebsterE."Be=erDisplayswithOrganicFilms."SciAmScienAficAmerican(2004):76-81.
Print.10. "KodakUnveilsWorld'sFirstDigitalCamerawithOLEDDisplay"EastmanKodak.3/2/2003.11. MichaelJ.Felton(2001)"Thinnerlighterbe=erbrighter,Today'sChemistatWork.";10(11):30-3412. Williams,Martyn."PCWorld-SonyReadiesOLEDTV".4/12/2007.13. Reisinger,Don."LGDisplayShowsoffPress-on'wallpaper'TVunder1mmThick-CNET."CNET.19May
2015.Web.6July2015.14. Schubert,E.Fred.“LightEmiHngDiodesandSolid-StateLighAng.”LightEmiHngDiodes
29
Acknowledgements NaAonalAeronauAcsandSpaceAdministraAon(NASA)
NASAGoddardSpaceFlightCenter,OfficeofEducaAon(GSFC)NASAGoddardInsAtuteforSpaceStudies(GISS)NASANewYorkCityResearchIniAaAve(NYCRI)
LaGuardiaCommunityCollege(LAGCC)
SamhitaRoy,Student,WWPSouthDr.JohnR.E.Toland,PhysicsProfessor,LAGCC
30
ORGANIC LIGHT-EMITTING DIODES
LIGHTING TOWARD A SUSTAINABLE ENVIRONMENT
31
Angelo Angeles (HS Teacher) Dr. Reginald Eze (Mentor)
Dr. Yasser Hassebo (Mentor)
Colleen Cleary (Undergraduate) Leo Panish (HS Student)
FAQ
ORGANIC LIGHT-EMITTING DIODES
LIGHTING TOWARD A SUSTAINABLE ENVIRONMENT
32
P-N Junction Layers of an OLED
Semiconductors Circuit Basics
Home
Natural Light
Applying the Layers Algorithm Steps
Black Levels/Contrast
Excitons
OLED Materials DBR
Microcavity
Equations
Circuit Basics
33
h=p://www.rkm.com.au/ANIMATIONS/animaAon-graphics/circuit-diagram.jpg
• PotenAaldifference(voltage)createsapush
• Currentflowsthroughcircuit
• Resistancerestrictsflow
• DirectcurrentandalternaAngcurrent
Main Menu
Semiconductors
34
h=p://lubricaAontechnology.com/uploads/images/pageimages/semiconductor.png
• ConducAvityincreaseswithtemperature.
• Allowsforgreatercontrolofcurrent.
• Usedintransistors,diodes,microprocessors.
• UsuallySiliconandGermanium
Main Menu
35
P-N Junction PMaterial
• Semiconductordopedwithanimpuritythathasfewervalenceelectrons
• ThemissingelectronleavesaposiCvely-charged"hole"
NMaterial
• Semiconductordopedwithanimpuritythathasextravalenceelectrons
• Extraelectronscanmovefreelyandconductelectricity
Main Menu
36
Diffusion
DriwMovementof
electronsduetoanelectricpotenAal
(current)
RandommovementofelectronstofillanenAre
space(nocurrent)
P-N Junction
Main Menu
37
• workswithdri`todecreasethedepleConzone
• negaCvecurrentpusheselectronsacross
• currentcreated
ForwardBias ReverseBias
• worksagainstdri`andwithdiffusion
• increasesthedepleConzone
• negligiblecurrent
CurrentcanonlyflowinonedirecCon.
circuitstoday.com/pn-juncAon-diode-characterisAcs
P-N Junction
Main Menu
38
CATHODE
EMISSIVELAYER
CONDUCTIVELAYER
ANODE
SUBSTRATE
Basic OLED Structure
• InventedbyKodakin1987
• Onlytwolayersbetweencathodeandanode.
Main Menu
Cathode and Anode • Cathode:Electrodethatreceiveselectronswhen
connectedtoapowersource
CATHODE
ANODE
• Anode:Electrodethatloseselectrons(or“receivesholes”)
• OwentransparentandmadeofindiumAnoxide(ITO)
39
• TypicallyareflecAvemetal
Main Menu
Emissive and Conductive Layers
EMISSIVELAYER
CONDUCTIVELAYER
• Thinorganicmaterialbetweencathodeandanode
40
• Electronsaretransportedtotheemissivelayer(ETL)
• “Holes”travelthroughconducAvelayer(HTL)
• Energyisreleasedintheformoflight
• ElectronsandholesrecombineintheETL
• Combinedthickness:100-150nanometers
Main Menu
SUBSTRATE
Substrate Layer
• AprotecAve,transparentlayer
• Lightpassesthroughtheclearsubstrate
41
Main Menu
Recombination and Excitons
• Electronsandholesrecombine.
• Exciton(electron-holepair)iselectricallyneutral.
• TherecombinaAonformsexcitonandreleaseslight.
42
h=ps://www.solarquotes.com.au/img/solar-pv-effect3.jpg
Main Menu
h=p://www.planetowunes.com/sound-audio-theory/so_media/standing_waves.gif
Microcavity
43
Main Menu h=p://www.nanowerk.com/spotlight/id25220.jpg
Distributed Bragg Reflector
44
Main Menu
h=p://www.batop.de/informaAon/pictures/quarter-wave_stack.jpg
h=p://www.webexhibits.org/causesofcolor/images/content/11z.jpg
OLED Materials
45
Main Menu
• Indium-Anoxide• Zincoxide
AnodeEmissiveLayer HoleTransportLayer(HTL)
• Tris-(8-hydroxyquinoline)Aluminum
• Coumarin• Dichloromethane
• Copperphthalocyanine
• Napthaphenylbenzidene
Cathode
• Aluminium• Silver• Magnesium• Indium• Lithium-fluoride
ElectronTransportLayer(ETL)
• Tris-(8-hydroxyquinoline)Aluminum
Mathematical Concepts
46
• NecessaryinordertocalculatereflecAonandtransmission.
• ThereisacharacterisAcmatrixfor:
UpperDBR, 𝑴↓𝑫𝑩𝑹↓𝟏
Characteristic Matrix
Microcavity,𝑴↓𝑪𝒂𝒗𝒊𝒕𝒚
LowerDBR, 𝑴↓𝑫𝑩𝑹↓𝟐
• ThetotalcharacterisAcmatrixcanbefoundusing:
𝑴↓𝑻𝒐𝒕𝒂𝒍 = 𝑴↓𝑫𝑩𝑹↓𝟏 ∗𝑴↓𝑪𝒂𝒗𝒊𝒕𝒚 ∗𝑴↓𝑫𝑩𝑹↓𝟐
Main Menu
Mathematical Concepts
47
ItispossibletocalculatethereflecAonandtransmission,givenby:
• 𝑴↓𝑻𝒐𝒕𝒂𝒍 , a2x2matrix,containsrealandimaginaryparts.
Reflection and Transmission Equations
• Thetopandbo=omtwoelementsofthematrixformtwocomplexnumbers,denotedas𝐵and𝐶,respecAvely.and𝐶,respecAvely.,respecAvely.
𝑅=(𝑦↓0 ∗𝐵−𝐶/𝑦↓0 ∗𝐵+𝐶 )(𝑦↓0 ∗𝐵−𝐶/𝑦↓0 ∗𝐵+𝐶 ) 𝑇= 4𝑦↓0 𝑅𝑒( 𝑦↓𝑠𝑢𝑏 )/( 𝑦↓0 ∗𝐵+𝐶) ( 𝑦↓0 ∗𝐵+𝐶)
Main Menu
Applying the Organic Layers • VacuumThermalEvaporaAon(VTE):
• Organicmoleculesareevaporatedandcondensed.• Kodak’soriginalprocess.• Expensiveandinefficient.
• InkjetPrinAng• Materialssprayeddirectlytosubstrate.• MostefficientandleastexpensiveapplicaAontechnique.
• OrganicVaporPhaseDeposiAon(OVPD)• Carriergastransportsevaporatedorganicmolecules• Moreefficientandlessexpensive.
Main Menu
Defining Parameters
• UserentersproperAesofthelayers:
49
• Convertfromdegreestoradians
IndexofrefracAon
Numberoflayers
Wavelength
Angleofincidence
h=p://www.schoolphysics.co.uk/age16-19/OpAcs/RefracAon/text/RefracAon_/images/1.png
Steps 1-2
Main Menu
Calculating Material Properties
• TestallpossibleiniAalincidentangles(-90°to90°)
50
• Findvalues:Incidentangleof𝑚↑𝑡ℎ layer, 𝜃↓𝑚 Thicknessofeachlayer,dOpAcaladmi=ance,y
ShowinghowthelightbehavesintheDBRstructure
Steps 3-5
Main Menu
Changing Wavelengths
• TestvisiblespectrumwitheachiniAalincidenceangle
51
• Determinesvaluesfor:Phasechange,𝛿↓𝑚
CharacterisAcmatrix, 𝑀↓𝑚
TotalcharacterisAcmatrix, 𝑀↓𝑇 ShowingthemaximumandminimumreflecAonintheDBRlayers.
Steps 6-7
Main Menu
Results
• ReceiveoutputwhenallpossibiliAeshavebeenchecked.Includes:
52
• Producegraphsfromresults
Reflectance,R
Transmi=ance,T
Phaseangle,,betweenRandT
SiegfriedDirr,StefanWiese,Hans-Herm
annJohannes,andWolfgangKow
alsky,“OrganicElectro-and
PhotoluminescentM
icrocavityDevices”,AdvanceMaterial,10(2),167-171,(1998).
Steps 8-9
Main Menu
Spectral Power Distribution
53
Main Menu
h=p://w
ww.lgoledlight.com
/
54
Main Menu
BlackdisplayedonanOLEDTV(lew)andLCDTV(right).
h=p://w
ww.consum
erreports.org/cro/news/2014/10/lg-
s-oled-tv-isn-t-the-best-tv-we-ve-ever-tested/index.htm
Black Levels and Contrast