SPRINGER BRIEFS IN APPLIED SCIENCES AND TECHNOLOGY NANOSCIENCE AND NANOTECHNOLOGY Pedro Ludwig Hernández Martínez Alexander Govorov Hilmi Volkan Demir Understanding and Modeling Förster-type Resonance Energy Transfer (FRET) FRET from Single Donor to Single Acceptor and Assemblies of Acceptors, Vol. 2 123 SpringerBriefs in Applied Sciences and Technology Nanoscience and Nanotechnology Series editor Hilmi Volkan Demir, Nanyang Technological University, Singapore, Singapore Nanoscienceandnanotechnologyoffermeanstoassembleandstudysuperstructures, composed of nanocomponents such as nanocrystals and biomolecules, exhibiting interestinguniqueproperties.Also,nanoscienceandnanotechnologyenablewaysto makeandexploredesign-basedartificialstructuresthatdonotexistinnaturesuchas metamaterials and metasurfaces. Furthermore, nanoscience and nanotechnology allow us to make and understand tightly confined quasi-zero-dimensional to two-dimensionalquantumstructuressuchasnanoplateletsandgraphenewithunique electronic structures. For example, today by using a biomolecular linker, one can assemblecrystallinenanoparticlesandnanowiresintocomplexsurfacesorcomposite structureswithnewelectronicandopticalproperties.Theuniquepropertiesofthese superstructures result from the chemical composition and physical arrangement of such nanocomponents (e.g., semiconductor nanocrystals, metal nanoparticles, and biomolecules).Interactionsbetweentheseelements(donorandacceptor)mayfurther enhancesuchpropertiesoftheresultinghybridsuperstructures.Oneoftheimportant mechanisms is excitonics (enabled through energy transfer of exciton-exciton coupling) and another one is plasmonics (enabled by plasmon-exciton coupling). Also, in such nanoengineered structures, the light-material interactions at the nanoscalecanbemodifiedandenhanced,givingrisetonanophotoniceffects. These emerging topics of energy transfer, plasmonics, metastructuring and the likehavenowreachedalevelofwide-scaleuseandpopularitythattheyarenolonger the topics of a specialist, but now span the interests of all “end-users” of the new findings in these topics including those parties in biology, medicine, materials scienceandengineerings.Manytechnicalbooksandreportshavebeenpublishedon individual topics in the specialized fields, and the existing literature have been typicallywritteninaspecializedmannerforthoseinthefieldofinterest(e.g.,foronly the physicists, only the chemists, etc.). However, currently there is no brief series available,whichcoversthesetopicsinawayunitingallfieldsofinterestincluding physics,chemistry,materialscience,biology,medicine,engineering,andtheothers. The proposed new series in “Nanoscience and Nanotechnology” uniquely supports this cross-sectional platform spanning all of these fields. The proposed briefs series is intended to target a diverse readership and to serve as an important reference for both the specialized and general audience. This is not possible to achieveundertheseriesofanengineeringfield(forexample,electricalengineering) or under the series of a technical field (for example, physics and applied physics), whichwouldhavebeenveryintimidatingforbiologists,medicaldoctors,materials scientists, etc. TheBriefsinNANOSCIENCEANDNANOTECHNOLOGYthusoffersagreat potential by itself, which will be interesting both for the specialists and the non-specialists. More information about this series at http://www.springer.com/series/11713 á í Pedro Ludwig Hern ndez Mart nez Alexander Govorov Hilmi Volkan Demir Understanding and Modeling ö F rster-type Resonance Energy Transfer (FRET) FRET from Single Donor to Single Acceptor and Assemblies of Acceptors, Vol. 2 123 PedroLudwig Hernández Martínez Hilmi VolkanDemir Schoolof Physical andMathematical Department ofElectrical andElectronics Sciences, LUMINOUS! Centreof Engineering, Departmentof Physics, and Excellencefor Semiconductor Lighting UNAM—National Nanotechnology andDisplays,TPI—The Institute of ResearchCentreandInstituteofMaterials Photonics ScienceandNanotechnology NanyangTechnological University Bilkent University Singapore Ankara Singapore Turkey Alexander Govorov and Department ofPhysics andAstronomy Schoolof Electrical andElectronic OhioUniversity Engineering, Schoolof Physical and Athens, OH MathematicalSciences, LUMINOUS! USA Centreof Excellence for Semiconductor LightingandDisplays,TPI—TheInstitute ofPhotonics NanyangTechnological University Singapore Singapore ISSN 2191-530X ISSN 2191-5318 (electronic) SpringerBriefs inApplied SciencesandTechnology ISSN 2196-1670 ISSN 2196-1689 (electronic) Nanoscience andNanotechnology ISBN978-981-10-1871-8 ISBN978-981-10-1873-2 (eBook) DOI 10.1007/978-981-10-1873-2 LibraryofCongressControlNumber:2016943801 ©TheAuthor(s)2017 Thisworkissubjecttocopyright.AllrightsarereservedbythePublisher,whetherthewholeorpart of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission orinformationstorageandretrieval,electronicadaptation,computersoftware,orbysimilarordissimilar methodologynowknownorhereafterdeveloped. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publicationdoesnotimply,evenintheabsenceofaspecificstatement,thatsuchnamesareexemptfrom therelevantprotectivelawsandregulationsandthereforefreeforgeneraluse. The publisher, the authors and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authorsortheeditorsgiveawarranty,expressorimplied,withrespecttothematerialcontainedhereinor foranyerrorsoromissionsthatmayhavebeenmade. Printedonacid-freepaper ThisSpringerimprintispublishedbySpringerNature TheregisteredcompanyisSpringerScience+BusinessMediaSingaporePteLtd. Contents 1 Applying Förster-Type Nonradiative Energy Transfer Formalism to Nanostructures with Various Directionalities: Dipole Electric Potential of Exciton and Dielectric Environment ... .... ..... .... 1 1.1 Spherical Geometry: Nanoparticle Case .... .... .... ..... .... 1 1.2 Cylindrical Geometry: Nanowire Case . .... .... .... ..... .... 2 1.3 Planar Geometry: Quantum Well Case. .... .... .... ..... .... 5 Reference .. .... .... .... ..... .... .... .... .... .... ..... .... 8 2 Förster-Type Nonradiative Energy Transfer Rates for Nanostructures with Various Dimensionalities . .... .... ..... .... 9 2.1 Cases of Förster-Type Energy Transfer to an Nanoparticle: NP → NP, NW → NP, and QW → NP... .... .... ..... .... 10 2.2 Cases of Förster-Type Energy Transfer to an Nanowire: NP → NW, NW → NW, and QW → NW. .... .... ..... .... 14 2.3 Cases of Förster-Type Energy Transfer to a Quantum Well: NP → QW, NW → QW, and QW → QW. .... .... ..... .... 18 2.4 Example: Energy Transfer Between Nanoparticles and Nanowires .. .... ..... .... .... .... .... .... ..... .... 21 2.5 Summary .. .... .... ..... .... .... .... .... .... ..... .... 23 References.. .... .... .... ..... .... .... .... .... .... ..... .... 25 3 Nonradiative Energy Transfer in Assembly of Nanostructures . .... 27 3.1 Energy Transfer Rates for Nanoparticle, Nanowire, or Quantum Well to 1D Nanoparticle Assembly . .... ..... .... 29 3.2 Energy Transfer Rates for Nanoparticle, Nanowire, or Quantum Well to 2D Nanoparticle Assembly . .... ..... .... 30 3.3 Energy Transfer Rates for Nanoparticle, Nanowire, or Quantum Well to 3D Nanoparticle Assembly . .... ..... .... 32 3.4 Energy Transfer Rates for Nanoparticle, Nanowire, or Quantum Well to 1D Nanowire Assembly.... .... ..... .... 33 v vi Contents 3.5 Energy Transfer Rates for Nanoparticle, Nanowire, or Quantum Well to 2D Nanowire Assembly.... .... ..... .... 35 3.6 Summary .. .... .... ..... .... .... .... .... .... ..... .... 36 References.. .... .... .... ..... .... .... .... .... .... ..... .... 37 Appendix A... .... .... .... ..... .... .... .... .... .... ..... .... 39 Chapter 1 ö Applying F rster-Type Nonradiative Energy Transfer Formalism to Nanostructures with Various Directionalities: Dipole Electric Potential of Exciton and Dielectric Environment In this chapter, we present analytical equations for the exciton electric potential inside and outside a nanostructure; including analytical expressions, for the long distanceapproximation,whicharederivedfortheoutsideelectricpotential.Finally, theeffectivedielectricconstantexpressions,forthislimit,areobtained.Thischapter is reprinted (adapted) with permission from Ref. [1]. Copyright 2013 American Chemical Society. 1.1 Spherical Geometry: Nanoparticle Case The electric potential for an exciton in the a-direction ða¼x;y;zÞ, illustrated in Fig. 1.1a, is given by (cid:1) (cid:3) (cid:1) (cid:3) ed a^(cid:2)r 2ðe (cid:3)e Þ r3 Uin ¼ exc 1þ NP 0 ð1:1Þ a e r3 e þ2e R3 NP NP 0 NP (cid:1) (cid:3)(cid:1) (cid:3) ed 3e r(cid:2)a^ Uout ¼ exc NP ð1:2Þ a e e þ2e r3 NP NP 0 where e and e are the nanoparticle (NP) and medium dielectric constants, NP 0 respectively. The electric potential is the same in any direction because of the spherical symmetry of the NP. In the long distance approximation the outside electric potential can be written as ©TheAuthor(s)2017 1 P.L.HernándezMartínezetal.,UnderstandingandModelingFörster-type ResonanceEnergyTransfer(FRET),NanoscienceandNanotechnology, DOI10.1007/978-981-10-1873-2_1 2 1 ApplyingFörster-TypeNonradiativeEnergy… (cid:1) (cid:3) ed r(cid:2)a^ Uout ¼ exc ð1:3Þ a e r3 eff where e is the effective dielectric constant given by eff e þ2e e ¼ NP 0 ð1:4Þ eff 3 1.2 Cylindrical Geometry: Nanowire Case In this case, the electric potential for an a-exciton ða¼x;y;zÞ, illustrated in Fig. 1.1a, is (a) (b) a.u) 5.0x10-5 OTouttasli dEele Ecltericct rPico Pteontteianlt iNalP N (Pa. u(a).u) P ( 4.0x10-5 N ntial 3.0x10-5 e ot P 2.0x10-5 c ectri 1.0x10-5 El Total 0.00 1 2 3 4 5 6 z (nm) (c) (d) NW (a.u) 45..00xx1100--55 OTouttasli dEele Ecltericct rPico Pteontteianlt iNalW N W(a. u(a).u) QW (a.u) 45..00xx1100--55 OTouttasli dEele Ecltericct rPico Pteontteianlt iQalW Q W(a. u(a).u) Total Electric Potential 231...000xxx1110000.0---5550 1 2 3 4 5 6 Total Electric Potential 231...000xxx1110000.0---5550 5 10 15 20 25 z (nm) z (nm) Fig.1.1 aSchematicofanexcitoninanNP,anNW,andaQW.Redcirclerepresentsanexciton inthea-direction.R istheNP(NW)radius.L istheQWcappinglayerthickness.b,c, NP(NW) QW anddElectricpotentialalongthe“z”axisforaz-exciton.Totalandlongdistanceapproximation electricpotentialforthez-excitoninside:banNP;canNW;anddaQW[Reprinted(adapted) withpermissionfromRef.[1](Copyright2013AmericanChemicalSociety)] 1.2 CylindricalGeometry:NanowireCase 3 Z X (cid:4) (cid:5) Uian ¼Uaþ eimue(cid:3)ikyAamðkÞImðjkjqÞ dk ð1:5Þ m Z X (cid:4) (cid:5) Uoaut ¼Uaþ eimue(cid:3)ikyBamðkÞKmðjkjqÞ dk ð1:6Þ m whereImðjkjqÞandKmðjkjqÞarethemodifiedBesselfunctionsoforderm,andUa is the a-exciton electric potential. After applying the boundary conditions at the surface of the nanowire (NW), the coefficients Aa and Ba are m m (cid:1) (cid:3) K ðjkjR Þ AaðkÞ¼ m NW BaðkÞ ð1:7Þ m I ðjkjR Þ m m NW 2ðe (cid:3)e ÞgaðjkjÞ BaðkÞ¼ (cid:6) j(cid:7)kj 0 NW m ð1:8Þ m eNW KImmððjjkkjjRRNNWWÞÞ ImðjkjRNWÞþe0KmðjkjRNWÞ where I ðjkjR Þ; K ðjkjR Þ, and gaðjkjÞ are defined as m NW m NW m ImðjkjRNWÞ¼Im(cid:3)1ðjkjRNWÞþImþ1ðjkjRNWÞ ð1:9Þ KmðjkjRNWÞ¼Km(cid:3)1ðjkjRNWÞþKmþ1ðjkjRNWÞ ð1:10Þ Z2p Z1 (cid:8) (cid:9) gaðjkjÞ¼ 1 dudye(cid:3)imueiky @Ua ð1:11Þ m ð2pÞ2 0 (cid:3)1 @q q¼RNW For an exciton in the y-direction (along the cylinder axis), the coefficient By m becomes 0 1 (cid:1) (cid:3) ByðkÞ¼ edexc ðe (cid:3)e Þ i jkj@(cid:6) 1 (cid:7) A ð1:12Þ 0 eNW NW 0 p KK01ððjjkkjjRRNNWWÞÞII10ððjjkkjjRRNNWWÞÞ eNWþe0 with an electric potential given by (cid:1) (cid:3) Z (cid:4) (cid:5) ed y Uout ¼ exc þ e(cid:3)ikyByðkÞK ðjkjqÞ dk ð1:13Þ y eNW ðq2þy2Þ32 0 0 In the long distance approximation, the coefficient By and the outside electric m potential are simplified as