organic light-emitting diodes · 2015-11-17 · organic light emitting diode lighting 3 • history...

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


14





•  IntroducAon


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


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


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


•  Parametricstudy

1.  MaximumtransmissionatBraggwavelength

2.  MaximumreflecAonatsurroundingwavelengths

•  Focusonsmallbandwidth

•  𝑅+𝑇=1


22





•  IntroducAon


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


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


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


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


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


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


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


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


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


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


1.

2.

3.

4.

Final ForMaximumTransmission:


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•  IntroducAon


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

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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



31

Angelo Angeles (HS Teacher) Dr. Reginald Eze (Mentor)

Dr. Yasser Hassebo (Mentor)

Colleen Cleary (Undergraduate) Leo Panish (HS Student)

FAQ



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

organic light-emitting diodes · 2015-11-17 · organic light emitting diode lighting 3 • history...

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