introduction-of-quantum-dot量子點技術介紹(附演講稿)-半導體物理全英文展示

QuantumDotsNanoscalecrystals<=100nmDiameterof≈10to50atomsContains100-100,000atomsIntrouctionIntrouctionEmissionspectrumcontrolledbysizeLargerQDsemitlongerwavelengthsSmallerQDsemitshorterwavelengthsPrinciple0Dimension:carriersareconfinedinalldirectionsStrongconfinement:smallerthan3BohrdiameterArtificialatoms:discrete,quantizedenergylevelsSemiconductorBandgap[eV]ExcitionBohrdiametr[?]Si1.1137(longitudinal)90(transverse)Ge0.6750(longitudinal)200(transverse)GaAs1.43280ColloidalsynthesisCVD/MBEElectricfieldconstraint

FabricationFabricationCuInS2quantumdotsfabrication:undergraduatechemistryexperimentinShanghaiTech

AccuratecolorsfordisplayApplicationphotostabilityWideexcitationspectrum&

NarrowemissionspectrumbiocompatibilityLongfluorescencelifetimelargerStokesshiftBiolabelApplicationLabelingApplicationStructureofeyeDoublecolorlabelingofantigensImageofhumankidneycellsLabelingApplication

Schematicofthedecetionofcancermarker-CEAFluorescencemagesforthedetectionofCEANanocrystalSizecontrollingemissioncolorOptical,biomedicalresearchapplicationConclusionReferences吳思敏,賈春平,劉莉芬,郜晚蕾,景奉香,金慶輝,張紅鋒,趙建龍.基于量子點熒光探針的高靈敏蛋白質檢測方法[J].華東師范大學學報(自然科學版),2016(02):144-152.陳朵朵,馬璐,李立家.量子點在生物學中的應用[J].氨基酸和生物資源,2009,031(001):48-52,73.Bureau-Oxton,C.,CamirandLemyre,J.,Pioro-Ladrière,M.NanofabricationofGate-definedGaAs/AlGaAsLateralQuantumDots.J.Vis.Exp.(81),e50581,doi:10.3791/50581(2013).AryaH,KaulZ,WadhwaR,TairaK,HiranoT,KaulSC(2005)Quantumdotsinbio-imaging:revolutionbythesmall.BiochemBiophysResCommun329:1173–1177Q&ADonotbehesitate.ThanksThankyouforwatching!HandoutNow,Letsstart.Afternoon,everyone.

Weknowthatlowdimensionmaterialshavesomespecialproperties,suchasgrapheneandcarbonnanotube.Soifwegofurtherandfocusonzerodimensionmaterial,whatitwouldbe?Thatisourtopictoday--quantumdots.Quantumdotisaninterestingtechnologygettingalotofattentionrightnow.BecauseTVmakersarebuildingtelevisionsthatusethem.Butwhatarequantumdots?andwhatdotheymeanforus?

2.AsismentionedinourlastclassonFriday.Quantumdotsarenanocrystals.Mostofthemarelessthanonehundrednanometers.Onlyabout10or50atomscanbeplaceintheirdiameterdirection.Theiroverallatomsnumberinonequantumdotsislessthanonehundredthousand.Thisimageindicatetheshell-corestructureofquantumdotswhichisusedtoeliminateit’ssurfacestates.Thisshowthequantumdots.

(Theyaretoosmalltoseebuthaveaspecialpower.)（需要指出的是，并非小到100nm以下的材料就是量子點，真正的關鍵尺寸取決于電子在材料內的費米波長。Itisimportanttonotethatquantumdotsarenotmaterialsassmallas100nm;therealcriticalsizedependsontheFermiwavelengthoftheelectroninthematerial.）

(Atpresent,quantumdotsover700nmandeven900nmhavebeensynthesized,buttheirfluorescenceefficiencyislow,whichrequiresmoreandmorein-depthresearch.)

3.Whentheyareilluminatedbyultravioletlight,electronsareexcitedtoastateofhigherenergy.Whentheexcitedelectrondropbackintovalenceband,itwillreleasesit’senergybytheemissionoflight.Thecoloroflightdependsontheirsize.Thesizeofthedotscanbepreciselymodified,sotheycangiveoffwhatevercolorwewant.Asisshowedinslides,LargerQDsemitlongerwavelengthslightsuchasorangeorred.SmallerQDsemitshorterwavelengthslightlikeblueandgreen.Thatisasimplemechanism.

4.Fromourcourse,weknowit’snanoscalesizemakequantumdotssospecial.TheimportantpointisBohrdiameter.Thesedataiscitedformourcourseslides.Inthiskindofsinglepoint,carriersareconstrainedstrongly.Sotheyhavediscrete,quantizedenergylevels,accordingtothelawsofquantumtheory.Itisabitlikeindividualatoms,sometimesknownas"artificialatoms."5.Uptonow,weknowquantumdotshaveexcellentopticalpropertiesbecausetheirnanoscalesize.Buthowcanweproducethem?Thecommonwayiscolloidsynthesis.Wecansynthesizequantumdotsinsolutionsbytraditionalchemicalprocesses.Duetolargebatchesofquantumdotscanbeproduced,thismethodispromisingforcommercialapplications.(Thereyaxisindicatesconcentrationofreactant,hereweinjecttheminsolution,hereitsaturate.Withtimeelapsing,colourofsolutionfromyellowtored)AnotheroneisEpitaxialgrowthmethod,itgrowsnanocrystalsonasubstratetoformquantumdots.ThismethodcanbesubdividedintoCVDandMBE(chemicalvapordepositionandmolecularbeamepitaxy.)Quantumdotsalsocanbedefinedbypatternedgateelectrode.Itmakesuseofthepotentialofthemetalelectrodetodistorttheenergylevelinthesemiconductor,soitformsaconstraintoncarriers.Becauseit’senergylevelcanbecontrolledprecisely,itcanbeusedinquantumcomputing.

6.Thesepictureshowusproducingquantumdotsbychemicalmethod.TheyaretookinchemicalexperimentcourseinShanghaiTech,inthiscampus.FromthiswecanknowthatIt’snotdifficultforustodothisexperiment,becausethisisacourseforundergraduatestudents,evenfreshman.Withtimeelapsing,thecolourtransformfrompaleyellowtoyellow,thenfromorangetoredwhenquantumdotsaregrowing.

7.Therearealotthingswecandowithquantumdots,fromsolarpanels,displaydevicestomedicalapplications,butyouprobablyheardthemdiscussedmostinrelationtoTVs.Therearetwomethodstoapplyquantumdotsindisplaydevices.Thefirstoneshowsputtingdifferentsizequantumdotsindiodes.Itwillemitred,green,bluelightwhenenoughvoltageisappliedonit.Thatisapixelwecalled.Butitisdifficulttomateitcometruebecauseofshortlifetime.SowehaveaaugmentationwaybaseonOLEDtechnologytomakeiteasy.TheyuseonlybluelightfromOLEDshineonquantumdots,soitcanemitredandgreenlight.ItmakespicturesmorecolourfulthanLEDandOLED.(ItcanachieveonehundredandtenpercentinNTSCcolourspace.)

8.Quantumdotisanewkindoffluorescentlabelingmaterials.Becausetheyhavethefollowingcharacteristicsandadvantageswhentheyarecomparedwithtraditionalmarkingmaterials.Thefirstoneis,Ithasgoodstability,soitcanenduremultipleexcitations.Thuswecanobservetheminalongtime.Thesecondoneis,It’sexcitationspectrumisrelativelywide.Usingsameexcitationlightsourcecanrealizemulticolorlabelingwithdifferentparticlesizes.Thethirdoneis,quantumdotscanhavelittleharmtoorganismsafterchemicalmodifications.Anotheris,theyhavealongfluorescencelifetime.Aftermostofthespontaneousfluorescencematerialhasdecayed,theirfluorescencestillexist.Thussignalwithoutbackgroundinterferencecanbeobtained.AnotheropticalpropertyisbroadStokesshift.Inthisway,thismeansavoidtheoverlapofemissionandexcitationspectrum.

9.Therearesomepicturesshowusit’sapplicationsonbiolabel.Thefirstoneshowsamicroscopyimageofhumankidneycells.Thecellnucleusisblue,andtheimmuneproteinsarelabeledwithagreenfluorescenttag.Themiddleoneareantigenslabeledbytwosizequantumdots.Therightoneshowsthestructureofeye.SoItcanbeusedtotrackthemovementofdrugs,ortostudythediseaseoftissuesinpatients’body.

10.Thereisanexamplethatwecanusequantumdotstodetectcancer.Atfirst,wemixthreekindsofmaterials,theyareCEA(akindofantigenofcancercell,youcanthinksitasasignalofcancer,itcancombinewithantibody),quantumdotsattach