Introduction-to-Molecular-Electronics-分子电子学简介

AnIntroductiontoMolecular(scale)Electronics于曦11.MolecularElectronics–ashorthistory2.Fabricationofthemolecularjunctions3.Basicprincipleofmolecularconduction4.Functionalmolecularelectronicdevices31950s-todayGreatleapofsemiconductorindustry4Moore’sLawHowsmalladevicecanbe?5:Biological_and_technological_scales_compared-en.svg#fileMoore’sLawScaleofourworld67Themolecularscaledeviceatwork~4nm~2nmTransistorDiodeConcept8GraphpresentedbycolonelLewisoftheUSAirForceinthefirstconferenceonmolecularelectronicsheldinNovember1958BottomUpTheinitialideaofMolecularElectronics9Insteadoftakingknownmaterialswhichwillperformexplicitelectronicfunctions,andreducingtheminsize,weshouldbuildmaterialswhichduetotheirinherentmolecularstructurewillexhibitcertainelectronicpropertyphenomena.Weshouldsynthesize,thatis,tailormaterialswithpredeterminedelectroniccharacteristic.Oncewecancorrelateelectronicpropertyphenomenawiththechemical,physical,structural,andmolecularpropertiesofmatter,weshouldbeabletotailormaterialswithpredeterminedcharacteristics.Wecoulddesignandcreatematerialstoperformdesiredfunctions.Inherentdependabilitymighteventuallyresult.WecallthismoreexactprocessofconstructingmaterialswithpredeterminedelectricalcharacteristicsMOLECULARELECTRONICS.1950sFirstproposalofMolecularElectronicsColonelC.H.LewisUSAirForce1958Top-downvsbottom-up1950s10Howtohookupcrocodileclipstoa10-9mobject?1950s111974Thefirsttheoreticalpaperaboutmolecularrectifier13Since1950sTheideaofmolecularself-assemblyEnzymecatalysisDNA-doublehelix14Since1980sTheideaofmolecularself-assemblyandsupramolecule15TheNobelPrizeinChemistry2016forthedesignandsynthesisofmolecularmachinesAMolecularShuttleStoddartetal,AMolecularElevator.Science,2004,303,18451980sScanningtunnelingmicroscopy(STM)181996Aresinglemolecularwiresconducting?Science1996,271,17051920How?TherealizationofMolecularElectronics+TopDownmicro-fabricationBottomUpmolecularself-assembly2122How?TherealizationofMolecularElectronics24ApplicationFunctionalMolecularDevicesRectifierNegativeDifferentialResistanceSwitchesTransistor25NatNanotechnol2013,8,37726NatureNanotechnology2013,8,38527SoWhatisMolecularElectronicsMOLECULARELECTRONICSstudieselectronicdeviceswithmoleculesasbuildingunits.Itexplorethefundamentalphysicalandchemicalprincipleconcerningchargetransportacrossmoleculesatmesoscopicscale,usingcross-disciplinarymethodsandtheoriesofmesoscopicphysics,chemistryandmicro-electronics.Theultimategoalistocreatefunctionalmolecule-baseddeviceslikeswitch,transistor,rectifieretc.MolecularElectronicsCuttingEdgeandCross-disciplineScience28ChemistryPhysicsMicro-electronicsPhysicalChemistry&ChemicalPhysicsSyntheticChemistryMicroscopicFabricationMesoscopicPhysicsMicroElectronicsQuantumChemistryMolecularElectronicsCuttingEdgeandCross-disciplineSciencePrincipleofquantumtransport291.MolecularElectronics–ashortintroduction2.Fabricationofthemolecularjunctions3.Basicprincipleofmolecularconduction4.Functionalmolecularelectronicdevices30Howtohookupcrocodileclipstoa10-9mobject?31NatRevMater2016,1,16002Anchorgroups321996Aresinglemolecularwiresconducting?Science1996,271,170533ScanningTunnelingMicroscopeBreakJunction(STM-BJ)SensorsBaselSwitz2012,12,7259–7298.3435ScanningTunnelingMicroscopeBreakJunctionSTM-BJScience2003,301,1221–1223.MechanicallyControllableBreakJunction(MCBJ)ChemSocRev2013,42,5642–60.36MechanicallyControllableBreakJunction(MCBJ)ChemSocRev2013,42,5642–60.3738Science1997,278,252ElectromigrationbreakjunctionSensorsBaselSwitz2012,12,7259–7298.39ElectrochemicalDepositionJunctionElectrochim.Acta2005,50,30414041Self-AssembledMonolayer(SAM)MacroscopicmonolayerjunctionMainChallenge:shortscontactdueto•Defectinthemonolayer•Monolayerbreakdownbyhotmealparticle•Stronginteractionbetweentopandbottommetal42MetalEvaporation:directvsindirectevaporation43ConductiveAtomicForceMicroscope(CP-AFM)44LiquidMetalBottomElectrodeHgGa-InAu、AgdoubleSAM√Al/Al2O3√noneSi√√LiquidMetalMethodMercuryGa-In45Protectinglayermethod–PEDOD:PSSNature2006,441,694650ElectrophoresissuspendednanowireAnnu.Rev.Phys.Chem.2012,63,2411.MolecularElectronics–ashortintroduction2.Fabricationofthemolecularjunctions3.Basicprincipleofmolecularconduction4.Functionalmolecularelectronicdevices52Chemistry–chemicalbondandelectrontransfer5455Chargetransferinchemicalsystem1992NobelPrizeinChemistryforhiscontributionstothetheoryofelectrontransferreactionsinchemicalsystems”ADLRememberelectronicexcitationandFrank-Condonprinciple?XX56q=1q=0q=0q=1ElectrontransitiontakesplaceinunstablenuclearconfigurationsobtainedviathermalfluctuationsNuclearmotionNuclearmotionq=0q=1q=1q=0Howchargetransferhappen?5758𝑘𝑒𝑡=2𝜋ℏ∣𝑉𝐷𝐴∣2ℱℱ𝐸𝐴𝐷=14𝜋𝜆𝑘𝐵𝑇exp[−𝜆+𝐸𝐷𝐴24𝜆𝑘𝐵𝑇]➢Transferstepisanenergyconservedprocess➢Freeenergychangeintheelectrontransferisduetorelaxing(dissipation)processFrank-CondonFactor𝐸𝐷𝐴𝑉𝐷𝐴ActivationQuantumstatetransitionRelaxationMarcuschargetransfertheoryChargetransferrate𝑉𝐷𝐴:electroniccouplingbetweenD/AElectrontransferTransitionstatetheoryArrheniusrateequat