Colloidal Quantum Dot Optoelectronics and Photovoltaics

330 Pages·2013·12.342 MB·English

by  Konstantatos G., Sargent E.H. (eds.)

ColloidalQuantumDotOptoelectronicsandPhotovoltaics
Capturing the most up-to-date research in colloidal quantum dot (CQD) devices, this
bookiswritteninanaccessiblestylebytheworld’sleadingexperts.Theapplicationof
CQDs in solar cells, photodetectors, and light-emitting diodes (LEDs) has developed
rapidlyoverrecentyears,promisingtotransformthefutureofcleanenergy,communi-
cations, and displays. This complete guide to the field provides researchers, students,
andpractitionersalikewitheverythingtheyneedtounderstandthesedevelopmentsand
begincontributingtofutureapplications.
Introductorychapterssummarizethefundamentalphysicsandchemistry,whilstlater
chaptersreviewthedevelopmentsthathavepropelledthefieldforwards,systematically
workingthroughkeydeviceadvances.ThescienceofCQDfilmsisexplainedthrough
the latest physical models of semiconductor transport, trapping, and recombination,
whilsttheengineeringoforganicandinorganicmultilayeredmaterialsisshowntohave
enabledmajoradvancesinthebrightnessandefficiencyofCQDLEDs.
GerasimosKonstantatosisanAssistantProfessorattheInstitutdeCie`nciesFoto`niques
(ICFO)inBarcelona. Hisresearchinterestslieintheareaofnanomaterials andnano-
structuresforoptoelectronicsandsolarcellapplications.Hisexpertiseisinthefieldof
colloidalquantumdots,andhewasawardedtheTR35SpainPrize2012andthe2013
Fresnel Prize for Applied Aspects for his salient contributions in the field of colloidal
quantumdotoptoelectronics.
EdwardH.Sargent is a Professor in the Department of Electrical and Computer Engi-
neering at the University of Toronto, where he holds the Canada Research Chair in
Nanotechnology.HisbookTheDanceofMolecules:HowNanotechnologyisChanging
OurLives(2005)hasbeentranslatedintoFrench,Spanish,Italian,Korean,andArabic.
HeisaFounderandCTOofInVisageTechnologies,Inc.

Colloidal Quantum Dot
Optoelectronics and
Photovoltaics
Editedby
GERASIMOS KONSTANTATOS
ICFO–TheInstituteofPhotonicSciences,Barcelona
EDWARD H. SARGENT
UniversityofToronto
UniversityPrintingHouse,CambridgeCB28BS,UnitedKingdom
PublishedintheUnitedStatesofAmericabyCambridgeUniversityPress,NewYork
CambridgeUniversityPressispartoftheUniversityofCambridge.
ItfurtherstheUniversity’smissionbydisseminatingknowledgeinthepursuitof
education,learningandresearchatthehighestinternationallevelsofexcellence.
www.cambridge.org
Informationonthistitle:www.cambridge.org/9780521198264
(cid:2)C CambridgeUniversityPress2013
Thispublicationisincopyright.Subjecttostatutoryexception
andtotheprovisionsofrelevantcollectivelicensingagreements,
noreproductionofanypartmaytakeplacewithoutthewritten
permissionofCambridgeUniversityPress.
Firstpublished2013
PrintedintheUnitedKingdombyTJInternationalLtd.PadstowCornwall
AcataloguerecordforthispublicationisavailablefromtheBritishLibrary
LibraryofCongressCataloguinginPublicationdata
Colloidalquantumdotoptoelectronicsandphotovoltaics/[editedby]GerasimosKonstantatos,
EdwardH.Sargent.
pages cm
Includesbibliographicalreferencesandindex.
ISBN978-0-521-19826-4(hardback)
1.Quantumelectronics. 2.Quantumdots. 3.Photovoltaiccells. I.Konstantatos,
Gerasimos,1979–editorofcompilation.
[DNLM:1.Colloids.]
TK7874.88.C65 2013
537.5–dc23 2013013116
ISBN978-0-521-19826-4Hardback
CambridgeUniversityPresshasnoresponsibilityforthepersistenceoraccuracyof
URLsforexternalorthird-partyinternetwebsitesreferredtointhispublication,
anddoesnotguaranteethatanycontentonsuchwebsitesis,orwillremain,
accurateorappropriate.
Contents
Listofcontributors pagexi
Preface xiii
1 Engineeringcolloidalquantumdots:synthesis,surfacechemistry,and
self-assembly 1
MarynaI.BodnarchukandMaksymV.Kovalenko
1.1 Colloidalsynthesisofinorganicnanocrystalsandquantumdots 1
1.1.1 Introductoryremarks:historyandterminology 1
1.1.2 Basicsofthesurfactant-assistedcolloidalsynthesisofNC
quantumdots 2
1.2 Long-rangeorderedNCsolids 7
1.2.1 Single-componentNCsuperlattices 7
1.2.2 MulticomponentNCsuperlattices 9
1.2.3 Shape-directedself-assemblyofNCs 13
1.3 Surfacechemistry–agatewaytoapplicationsofNCs 16
1.3.1 Organiccappingligands 16
1.3.2 Completeremovaloforganicligandsandinorganicsurface
functionalization 19
References 20
2 Aqueousbasedcolloidalquantumdotsforoptoelectronics 30
VladimirLesnyakandNikolaiGaponik
2.1 Introduction 30
2.2 AqueouscolloidalsynthesisofsemiconductorNCs 32
2.2.1 ZnXNCs 32
2.2.2 AlloyedZnSebasedNCs 34
2.2.3 CdXNCs 35
2.2.4 Core/shellCdTebasedNCs 36
2.2.5 AlloyedCdTebasedNCs 37
2.2.6 CdSe,CdSe/CdSNCs 39
2.2.7 HgXandPbXNCs 39
vi Contents
2.2.7.1 HgXNCs 40
2.2.7.2 PbXNCs 40
2.3 AssembliesandfunctionalarchitecturesofNCs 41
2.3.1 LbLassemblytechnique 43
2.3.2 AssemblyofNCsonmicro-andnano-beads 46
2.3.3 CovalentcouplingofNCs 47
2.3.4 Controllableaggregation 48
2.3.5 Nanowiresandnanosheets 49
2.3.6 Nanocrystalbasedgelsandaerogels 49
2.4 Conclusionsandoutlook 50
References 51
3 Electronicstructureandopticaltransitionsincolloidal
semiconductornanocrystals 59
ToddD.KraussandJeffreyJ.Peterson
3.1 Introduction 59
3.2 Foundationalconcepts 60
3.3 Asimplemodel 65
3.4 Experimentalevidenceforquantumconfinement 67
3.5 Engineeredquantumdotstructures 71
3.6 Advancedtheoreticaltreatments 73
3.7 Atomisticapproaches 76
3.8 Currentchallengesandfutureoutlook 80
References 81
4 Chargeandenergytransferinpolymer/nanocrystalblends:physicsanddevices 87
KevinM.NooneandDavidS.Ginger
4.1 Introduction 87
4.2 AbriefhistoryofQD/polymeroptoelectronics 88
4.2.1 Quantumdotlightemittingdiodes(QD-LEDs)–size-tunable
emissionacrossthespectrum 88
4.2.2 Quantumdotphotovoltaics(QD-PV)andphotodetectors–
convertingphotonstoelectrons 90
4.2.2.1 QD-PVs 90
4.2.2.2 Quantumdotphotodetectors 93
4.3 TheQD–organicinterface–ligandsandmore 96
4.3.1 Ligands 96
4.3.2 Energetics 98
4.3.2.1 ChargetransferandFo¨rsterresonanceenergytransfer
(FRET)inQD-LEDs 99
4.3.2.2 TypeIIheterojunctionsandchargetransferinQD-PVs 99
4.4 Conclusionandfutureoutlook 104
References 105
Contents vii
5 Multipleexcitongenerationinsemiconductorquantumdotsand
electronicallycoupledquantumdotarraysforapplicationtothird-generation
photovoltaicsolarcells 112
MatthewC.Beard,JoeyM.Luther,andArthurJ.Nozik
5.1 Introduction 112
5.2 Relaxationdynamicsofphotogeneratedelectron–holepairsinQDs 115
5.2.1 Transientabsorptionspectroscopy(TA) 117
5.3 Multipleexcitongeneration(MEG) 121
5.3.1 MEGinQDs 121
5.3.2 MEGcontroversyandroleofphotocharging 125
5.3.3 MEGefficiencyandcomparisontoimpactionizationinbulk
semiconductors 128
5.4 QDsolarcells 131
5.4.1 MEGphotocurrentanddeterminationoftheinternalquantum
efficiency(IQE)inQDsolarcells 133
5.5 QDarrays 136
5.5.1 MEGinPbSeQDarrays 137
5.6 Conclusions 140
References 141
6 Colloidalquantumdotlightemittingdevices 148
VanessaWood,MatthewPanzer,Seth-CoeSullivan,andVladimirBulovic
6.1 Introduction 148
6.2 WhyQDsforLEDs? 148
6.2.1 Saturatedcolors 148
6.2.2 Solutionprocessable 150
6.2.3 Stability 150
6.3 QDanddevicephysicsinfluencingLEDperformance 151
6.3.1 Quantifyingtheluminescenceefficiency 151
6.3.2 QDsurfacestates 152
6.3.3 QDcharging 153
6.3.4 ChargetransportinQDfilms 154
6.3.5 Fielddrivenluminescencequenching 154
6.3.6 Isolatingtheeffectsofchargeandfield 155
6.4 CharacterizingQD-LEDs 157
6.5 QD-LEDsbasedonopticaldownconversion 160
6.6 QD-LEDsbasedonorganicchargetransportlayers 161
6.6.1 DepositionofQDs:spincasting,phaseseparation,and
microcontactprinting 161
6.6.2 OperationofcolloidalQD-LEDs 163
6.7 QD-LEDswithinorganicchargetransportlayers 165
6.7.1 Reasonsforinorganicchargetransportlayers 165
viii Contents
6.7.2 FabricationofallinorganicQD-LEDs 165
6.7.3 OperationofQD-LEDwithinorganicchargetransport
layers 166
6.7.4 ImprovingtheefficiencyofQD-LEDswithinorganiccharge
transportlayers 167
6.8 Futurework 167
References 168
7 Colloidalquantumdotphotodetectors 173
GerasimosKonstantatos
7.1 Introduction 173
7.1.1 Applicationsoftop-surfacephotodetectors 173
7.1.2 Colloidalquantumdots(CQDs)forlightdetection 174
7.2 Fundamentalsofphotodetectors 175
7.2.1 Typesofphotodetectors 175
7.2.2 Figuresofmerit 176
7.3 Priorartinsolution-processedphotodetectors 177
7.4 Solution-processedQDphotoconductors 179
7.4.1 PhotoconductivegainandnoiseinPbSQDphotodetectors 179
7.4.2 Visible-wavelengthandmultispectralphotodetection 183
7.4.3 Controloftemporalresponseinphotoconductivedetectorsvia
trapstateengineering 185
7.5 CQDbasedphototransistors 187
7.6 CQDphotodiodes 190
7.7 Conclusions–summary 193
References 195
8 Opticalgainandlasingincolloidalquantumdots 199
SjoerdHoogland
8.1 Introduction 199
8.2 Opticalpropertiesofcolloidalnanocrystalquantumdots 200
8.3 Carrierdynamicsincolloidalquantumdots 202
8.3.1 Augerrecombination 205
8.3.2 Poissonstatisticsandstatefilling 206
8.4 Gaininsolidstatenanocrystalquantumdotfilms 207
8.4.1 Amplifiedspontaneousemission(ASE) 208
8.4.2 Variablestriplength(VSL)foropticalgainmeasurements 209
8.4.3 Experimentaltechniquesforwaveguidelossmeasurementin
colloidalquantumdotfilms 209
8.4.4 Modalgaininvisiblecolloidalquantumdotsbasedoncadmium
chalcogenides 211
8.4.5 Modalgainininfraredcolloidalquantumdotsbasedonlead
chalcogenides 213