该【the theory of thermally activated delayed fluorescence for organic light emitting diodes t. j. penfold资料 】是由【小舍儿】上传分享，文档一共【11】页，该文档可以免费在线阅读，需要了解更多关于【the theory of thermally activated delayed fluorescence for organic light emitting diodes t. j. penfold资料 】的内容，可以使用淘豆网的站内搜索功能，选择自己适合的文档，以下文字是截取该文章内的部分文字，如需要获得完整电子版，请下载此文档到您的设备，方便您编辑和打印。:..ViewArticleOnlineViewJournalmmunicationsAcceptedManuscriptThisarticlecanbecitedbeforepagenumbershavebeenissued,todothispleaseuse:,,mun.,2018,DOI:–eptedManuscript,,beforetechnicalediting,,authorscanmaketheirresultsavailablemunity,incitableform,,’sISSN1359-7345standardTerms&Conditionsandtheethicalguidelines,,,,,,,,?******@C2n(2n=68and80).******@D5h-:..mViewArticleOnlineDOI:-RXUQDO1DPHTheTheoryofThermallyActivatedDelayedFluores-a,(TADF)hasbeenreinvigoratedinrecentyearsowingtotheirpotentialtobeexploitedasemittersinhighlyaniclightemittingdiodes(OLEDs).However,designingnewmoleculesthatexhibitef?cientTADFisanon--?uorescencerate,,adetailedunderstandingofthefundamentalfactorsin?,,(OLEDs)andwereableTheconventionalviewofmolecular?uorescenceisasatwosteptodemonstratehighef?ciencyelectroluminescenceforthe?,whichsubsequently,andignoringallotherpossiblepath-drivingforceforasigni?cantresearchinterestindevelopingnew$FFHSWHGways,-knownasprompt?,dependingoncess6–:46:,plicatedThehugeliteratureonnewTADFemittersillustratesthattoroute,,thesingletexcitedstatedatethedesignofnewTADFmoleculeshaslargelyfocuseduponstatedecaysviaintersystemcrossing(ISC)-scalesyntheticprogramsaimedatdevelopingandthenex-Subsequently,ifthephosphorescenceandnonradiativedecayofploitingstructure-,whilethesethetripletstateisslowandtheenergygapbetweenthesingletcanleadtoincrementalprogressandsimpledesignrulesthatcanandtripletstatesissmallenough(normally),thenasec-beusedtomanipulateaspeci?cproperty,suchastheemissionondISC,oftencalledreverseintersystemcrossing(rISC),backtoorabsorptionwavelength,essfulinsimulta-?uorescence(DF),atleastinpart,duetotheapparentcontradictoryre-&KHP&,,toachievehighef?,,E-typedelayed?,whichminimisesandco-workers5,exploitedtherISCmechanismofDF,renamingtheexchangeenergyandthereforethesinglet--itThermallyActivatedDelayedFluorescence(TADF),--SchoolofNaturalandEnvironmentalSciences,NewcastleUniversity,New-castleuponTyne,NE17RU,.******@-bPhysicsDepartment,DurhamUniversity,SouthRoad,Durham,DH13LE,Unitedtionally,andhasthepotentialtosigni?cantlyspeed-upthescreen--+PVSOBM/BNF<ZFBS><WPM>1–10|1:..mPage2of10ViewArticleOnlineDOI:,>>kF,mustbeandoftenisbrokentosup-,attheheartoftheseap-portnewemitterswithstronger?uorescenceyields14,?cmolecularpropertiesregime,icprocess16,whichandthereforeasforexperimentaldesign,adetailedunderstand-ignoringnon-radiativepathwaysiswritten:ingoftheTADFmechanismmustbeachievedtooptimisethesedSsocalleddescriptors.=(kF+kISC)[S]+krISC[T](3a)dtdT=kISC[S](kP+krISC)[T](3b)(a)$(b)$(c)$dtdG=kF[S]+kP[T](3c)dtG,TandSrepresenttheground,tripletandsingletstates,respec-,krISCistherateofrISC,kFistherateof?uorescence,:010101dS=dt(kF+kISC)krISC0S(t)BdT=dtC=Bk(k+k)0CBT(t)C(4)***@******@******@(a),HOMO(b)andLUMO(c)of3,7-PTZ-=dtkFkP0G(t)Inthisfeaturearticle,recenttheoreticalworkaimedateluci-icequations,yieldingthetime-dependentpopulationofeachoftheelectronicstatesisobtaineddatingafullunderstandingofTADFacrossarangeoftime--ticaspectsofTADF,posedofaphenothiazinedonorandadibenzothiophene-S,S-using:eptor(3,7-PTZ-DBTO2).Thisstructure,u-Mt0DQXVFULSWpiedmolecularorbital(HOMO)upiedmolecularP(t)=eP(0)(5)orbital(LUMO)areshowninFigure110–,thisisnotthewhereP(0)istheinitial(t=0)populationofeachstateandMishighestperformingTADFemitter,itrepresentsanexcellentpro-,,whilefordetailsregardingexperimentalphoto-physicalcharacterisation,-1PTZ-DBTO2inTolueneSingletPopulation(Fit)SingletPopulation(Fit)DPTZ-DBTO2inTolueneicsofThermallyActivatedDelayedTripletPopulationTripletPopulation$FFHSWHGFluorescence-210InitialstudiesofTADFwereinterpretedintermsoftheequilib-:46:,?(I)anic-<<krISC,andthereforethemoleculespendssuf?cienttimeintheexcitedstateforaequi-Intensity()-4Therelativepopulationofthetwostatescanbeexpressedusinganequilibriumconstant:(a)(b)10-5[S1]10-810-710-610-510-410-3-8-7-6-5-4-3K=Time(s)101010101010Time(s)&KHP&RPPkrISC1DES1T1==exp(1)?t(blacksolidline)usingEquation5ofthetime-dependent[T1]kISC3kBTemissionintensity(blackcircles)of3,7-PTZ-DBTO2(a)10,11anditsmakingitpossibleto?ndtherateofthewholeTADFprocessD-A-DanalogueDPTZ-DBTO2(b)-(kTADF),?uorescence,astheproductofthe?tsyieldsthefollowingparametersk=107s1,k=107s1,61FISC71amountofpopulationintheS1stateandtheratelimitingstep,krISC=10sfor3,7-PTZ-DBTO2and(b)kf=10s,;k=107s1,k=106s1forDPTZ-DBTO2.ISCrISC1DES1T1kTADF=kFexp(2)3kBTIndeed,Figure2ashowstheexperimentalemissiondecayofImportantly,thismotivatesadesignprocedurewhichisbased3,7-PTZ-DBTO2intoluene10(blackcircles)plottedwitha?tofsolelyuponi)minimisingDES1T1andii)makingthemoleculethetime-,thekeyagreementisobtainedusingkF=6107s1,kISC=1107s12|+PVSOBM/BNF<ZFBS><WPM>1–10:..mViewArticleOnlineDOI:=106,ordingtotheinterelectrondistance,r12:-A-Danalogue,=erfc(mr12)r12+erf(mr12)r12(6)r12DPTZ--cellentOLEDperformance>19%externalquantumef?ciency2Rx2177whereerf(x)=p0exp(t)dtanderfc(x)=1erf(x).This(EQE).Inthiscasethebest?tisachievedusingkF=10ps1,k=107s1,k=106s1,alsoingoodagree-providesthe?,thesimilar-electron-electrondistances,ingthelimitationoflocalityityinthephotophysicsofthetwomoleculesdemonstratesthatformostexchange--A-D-typemoleculesexhibitingintrinsicallymoreef?cientTADFtuningapproachwasinitiallyproposedbyBaer,Kronik,andco-thancorrespondingD-(eHOMO)andthe?rstionisationponentswithexponentials,ispotential(IP)oftheneutralsystemandtheenergydifferencebe-,asshowninFigure2tweenenergyoftheHOMOoftheanionicsystem,eHOMO(N+1)andtheelectronaf?nity(EA)(redtrace),itnaturallyprovidesthetime-:roll-offef?(m)=jem(N)+IPm(N)j(7a)0HOMO3TheElectronicStructureofTADFEmittersJ(m)=jem(N+1)+EAm(N)j(7b)1HOMOThe?rststeptounderstandingthecharacteristicsofaparticu-Thereforethegoalistominimisetherelationship:larTADFemitterissimulatingtheexcitedstatepropertiesatim-J(m)=J0(m)+J1(m)(8)portantgeometriesonthepotentialenergysurface,,forwhichTheresultsobtainedfromthesimulationsinrefs28,29gavequan-mostTADFemitterscanbeclassed,time-dependentdensityfunc-,itistionaltheory(TDDFT)19,20isusuallythemethodofchoiceduenotedthattheoptimalvalueofmisbothmoleculeandgeometrytoitsappealingtrade-putationalef-dependent.?,theimportanceofcharge-transferstatesintheFigure3showstheexperimentalabsorptionspectrumof3,7-TADFmechanismisatoddswiththewidelydocumentedlimita-PTZ-,spectracalculatedusingtheM062X(blue)andoptimallytunedmonlyusedfunctionals,LC-BLYP(red),astheywillunderestimatetheenergyofbetweenthecalculatedandexperimentalspectramakingitpos-$,forexampleappandCTstate,-:46:-outthiswork,ithasbeenfoundthattheM062Xfunctional31sonfortheenergygapbetweenthesingletandtripletCTstates,providesagooddescriptionoftheexcitedstatepropertiesof3,7-paredtothegroundstatewillPTZ-,?-ishelpedusingTDDFTwithintheTamm-Dancoffapp
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