光子学前沿讲座-2015进展有机和生物光电材料与器件

有机和生物光电材料与器一、有机光电材料研究进展与发展趋有机光电材料是一类具有光电活性的有机材料，广泛应用于有机发光二极、有机晶体管、有机能电池、有机器等领域。有机光电材料通常是富含碳原子、具有大π共轭体系的有机分子，分为小分子和聚合物两类。与无机材料相比，有机光电材料可以通过溶液法实现大面积和柔件。此外，有机材料具有多样化的结需要的性能，能够进行自组装等自下而上的器件组装方式来纳米器件和分子器件。有机光电材料与器件的发展也带动了有机光电子学的发展。有机光电子学是跨化学、信息、材料、物理的一门新型的交叉学科。N N四苯基卟啉分子结发光聚合物PPV分子堆非线性极化i

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代表线性电极化率张量，而

和 别代表二阶和三阶非线性电极化率张量有机发光二极有机电致发光的研究工作始于20纪60年代，但直到1987年柯达公司采用多层膜结构，才首次得到了高量子效率、高发光效率、高亮度和低驱动电压的有机发光二极管（OLED）。这一突破性进展使OLED成为发光器件研究的热点。与传统的发光和显示技术相比较，OLED具有驱动电压低、体积小、重量轻、材料种类丰富等优点，而且容易实现大面积、湿法以及柔件的采采用红、绿、蓝三种基础色LED，通过电脑控制十万控制点，上百万个器件，呈现出1600万种颜色近年来，OLED技术飞速发展2001年，索尼公司研制成功13英寸全彩OLED示器，证明了OLED以用于大型平2002年，三洋公司与柯达公司联合推出了采用有源驱动OLED示的数码相机，标志着OLED的又迈出了坚实的一步；2007年，索尼公司推出了11英寸的OLED色电视机，率先实现OLED中大尺各大公司和研究机构展示的开发的OLED德 应用研究促进，透明除了在显示领域的应用，白光OLED为一种新型的固态光源也得到了广泛关注。2006年，柯尼卡美能达技术中心开发成功了1000cd/m2初始亮度下发光效率64lm/W、亮度半衰期约1万小时的OLED白色发光器件，展示了OLED在大面积平板照明领域的前景。目前WOLED最高效率的来自德国Leo教授的研究组，他们采用红绿蓝三种磷光，了1000cd/m2下效率124lm/W的白光器件，效率低掺杂聚合物发光二极ThemolecularstructuresofP[(por)A-S](a)andP[(por)A-AN](b) CO

n n Steady-stateabsorptionspectraofp[(por)A-S]atporphyrincontentof0.1%(a)and0.27%(b).IntensityIntensityIntensityIntensity 0

0 0

Wavelength

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Thetime-integratedluminescencespectraofP[(por)A-S]andP[(por)A-AN]fiattheexcitationwavelengthof400nmandthepulsespowerof6mW.IntensityIntensity

p[(por)A-p[(por)A-p[(por)A-

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showthetransientluminescencerelaxationprocessesoftheP[(por)A-AN]andP[(por)A-S]fiattheemissionpeakofabout650nm.p[(por)A-00IntensityIntensity IntensityIntensity

ThetransientluminescencerelaxationprocessesoftheP[(por)A-AN]andP[(por)A-S]fiattheemissionpeakofabout650nm.ThetransientluminescencerelaxationprocessesoftheP[(por)A-AN]andP[(por)A-S]fiattheemissionpeakofabout650nm.p[(por)A-p[(por)A-1IntensityIntensityIntensityIntensity- Delay

- DelayTableIThetablesummarizesthetimeconstantsofp[(por)A-AN]p[(por)A-S] atthemainemissionpeakofabout650IntensityIntensity--

P[(por)A-

-400- 80010001200140016001800DelayP[(por)A-- 10001200140016001800DelayP[(por)A-IntensityIntensity-400- 80010001200140016001800DelayOneEnergyEnergy RotateAngleFig.8Theinteractionpotentialenergyasthefunctionoftherotationangleoftheporphyrinmoleculesinthe10wt.%p[(por)A-AN]film.Figs.9Themolecularstericstructuresofthep[(por)A-AN]atthenumber(n)ofthecyano-groupsbetweentheneighbouringporphyrinmoleculesare4(a)and3(b),respectively. 有机全光开Inopticalcommunications,informationispassedviaguidedopticalbeamswithwavelengthstypicallybetween1.3and1.5μm,whereopticalfibertransmissionlossesareminimized.All-switchesdeflectordelaythesignalbeamthroughachangeintherefractiveindexofanonlinearopticalmaterialthatisstimulatedbyasecondlight2010VOL327Inl-opticalswitch,acontrolbeamorpulsemodulatesthedirectionofaninputsignalandtherebyswitchesbetweenanonandanoffstate.Inanonlinearopticalmaterial,refractiveindexandpropertiesdependonlightintensityatstrongintensities.Thehighspeed(<100ps)ofopticalswitchingrelativetoelectro-opticalswitchingoffersthepossibilityofdramaticincreasesinthespeedandefficiencyofavarietyofCurrently,opticalswitchingisbymeansofrareearth–dopedopticalamplifiersorsemiconductoropticalamplifiers.Thesecomponentsarecostlytomanufacture,restrictingthetechnologytospecialapplicationssuchaslong-distancePi-conjugatedmolecularmaterialshavestrongopticalnonlinearitiesandcouldthereforeperformeffectivelyinall-opticalswitches.Moreover,theactivematerialscostlittleandshouldbeeasytointegrateintowaveguidedevices.Organicopticalswitchingdevicescouldthusmassivelyreducethecostofall-opticalsignalprocessing.PossibleapplicationsrangefromeverydaydommunicationsanddatascreeninginhealthcaretofastopticalInpi-conjugatedmaterials,polarizationthemoleculebytheincidentlightfieldcausesachangeinitsrefractiveindex,Δn.Thischangeisproportionaltotherealpartofthethird-ordercoefficient,γ,intheexpansionofpolarizabilityintermsofelectromagneticfieldstrength.Forhigh-performanceall-opticalswitches,themolecularmaterialshouldthusofferalargeγ,aswellaslowabsorptionlossesand—forfastswitching—ashortlifetimeofthenonlinearexcitedstate.Largeγarefoundinpolyene-typemoleculesdesignedsothattheC–Cbondlengthsaresimilarandthattheelectronicgroundstateisdelocalizedalongthewholemolecule.Foragivenoperatingwavelength,γincreasesveryrapidlywithmolecularlength,L.Onestrategytoachievehighγisthereforetoincreasethelengthofthemolecule.However,longpolyene-typemoleculestendtodistort,therebylosingthebondlengthsymmetrythatenablesground-statedelocalizationandthuslimitingthevalueofγ.Afurtherimportantcompromiseinthedesignoforganicnonlinearopticalmaterialsresultsfromtheneedtokeepallabsorptionlosseslowwhile γhigh.γcanbeenhancedbyusingamaterialinwhichthe linearopticaltransition,Eg,liesjustabovetheoperatingphotonenergy,hω(thenonresonanteffect),butatthehighfieldstrengthsusedinnonlinearoptics,electronictransitionsinvolvin ophotonsandwithtwicethephotonenergy2hωc eimportant.Therefore,theelectronicstructuremustbedesignedthatno(linearornonlinear)opticaltransitionsoccuratOneapproachistochoosealarge-gapmoleculeEg>2hω(for munications,thatmeansEg>1.65eV),butthesizeofγisthenternativeistofindalow-gapmoleculewhich2hωliesinagapbetweendifferenttwophotontransitions.Inthisconfiguration,γisenhancedbythenonresonanteffectandmolecularlengthislesscritical.However,itischallengingtodesignmoleculeswiththerequiredelectronicstructure.Absorptionlossesareminimizedbychoosingaphotonenergyhωsuchthatnolinearornonlineartransitionsareexcitedateitherhωor2hω.If,inaddition,hωliesclosetothe lineartransitionEg,thenγisenhancedthroughanonresonanteffect.Halesetal.nowreportabreakthroughthedesignandsynthesisofapolymethine-typedyemoleculecappedwitharomaticselenium(Se)–containingendgroups.Thearomaticendgroupsallowthefrontiermolecularorbitalstoextendbeyondthepolymethinechain;theythuseffectivelyincreasetheconjugationlengthandreduceEgwithoutthesymmetry-breakingproblemencounteredinlongchains.theSesubstitutionincreasesthemomentabovethevalueexpectedforthegivenpolymethinechainlength.two-photonabsorptionlossesatmunicationswavelengthsareminimizedinthesemoleculesbecauseofagapinthetwo-photonabsorptionspectrumat2hω.ThecombinationofhighγandlowabsorptionlossesresultsinanunprecedentedratioofγtoIftheseresultsforsolutioncanbereproducedinsolidfi,themoleculescouldfindapplicationassomeofthehigh-performance,low-costall-opticalthedesignandsynthesisoffunctionalpi-conjugatedmaterialsforspecificpurposes:Polyfluorenepolymerswithasmallfractionofshortsidechainscanachievebothgoals,becausethesidechainsincreaseinterchainhopandraisechargemobilitybyalmosttwoordersofmagnitude,butdonotreducetheluminescenceefficiency.有机光子晶体全光开threekeycharacteristics:lowpumppower,highswitchingefficiencyandfasttimeresponse.Thebasicideaistomodifytherefractive-indexcontrastbyusingpumplight.Polystyrenedopedwithcoumarin153(C153)wasusedasthematrixofatwo-dimensionalphotonic-bandgapmicro.Nature2008.,acompositematerialmadeofchromophoreandpolymerwasusedasthematrixforthephotoniccrystals.theinterelectrontransferprocessbetweenthechromophoreandpolymerensuresanultrafastresponsetime. Scanning-electron-microscopy(SEM)imagesofthephotonicbandgapmicro Thefemtosecondpumpandprobemethodwasusedtostudythetransmittancepropertiesofthephotonic-bandgapmicro Toperformtheall-opticalswitching,wemeasuredandplottedthetransmittancechangesoftheprobelightasafunctionofthetimedelaybetweenthepumpandprobepulses.Thewavelengthoftheprobelightwascentredat788nmandtheenergyofthepumplightwas520fJ.Thewavelengthofthepumplightwas394nm,whichwaswithinthelinearabsorptionbandofpolystyreneandC153andledtoanear-resonantenhancementoftheopticalnonlinearity.ThesignalprofiletakesontheshapeofaninversetriagonalInthepeakregionsofthetriagonalwave,thepumppulsewasfarawayfromtheprobepulseinthetemporalsequence.Thetransmittanceoftheprobelightmaintained umvalue,92%.Theopticalswitchwasinthe‘on’Thetransmittancechangedwhenthelightwasswitchedon.Inthetroughregionsofthetriagonalwave,thepumpandprobepulseoverlappedtemporally.Themicromodeshiftedinthephotonicbandgapbecauseofthepump-inducedvariationoftheeffectiverefractiveindexofthephotonicThetransmittanceoftheprobelighttotheminimumvalue,10%,whichcorrespondstothe‘off’stateforopticalForadopedpolystyrenemicro.Thewavelengthoftheprobelightwas788nmandtheenergyofthepumplightwas520fJ.Thethickredlinerepresentstheexponentiallyfittedresult.Theinsetshowstherelativeenergylevelsofthepolystyreneanddyemolecules.GSrepresentsthegroundstateandLESisthelowestexcitedstate.Thevalueofthenonlinearrefractiveindexwasestimatedtobefourordersofmagnitudelargerthanthatofundopedpolystyreneunderoff-resonantexcitation.highspeedopticalswitchingofapolymeropticalamplifierturnofftheamplificationforonepulseinapulseTheswitchingisachievedbygainmodulationinaconjugatedpolymertoimplementall-opticalAppl.Phys.lett.2008.92Gratingswereetchedintothesilicasubstratebyreactiveionetching,tocouplethesignalintoandoutofthedevice.Thegainmediumwasaconjugatedcopolymerconsistingoffluoreneandbenzothiadiazoleunits.Theactiveregionoftheamplifierliesbetweenthegratingcouplersandwaspumpedatawavelengthof497nm.Thesignalpulseswereat580nm.Acontrolpulseat800nmwasappliedtothepumpedregion.theunamplifiedsignalpulsesopensymbolsandsolidsymbolsshowthesamepulsesequenceamplifiedwithaWhenthecontrolpulseisapplied,theamplifiedmiddlepulsedropsinintensitybyafactorof3andisonly30%higherthanthenonamplifiedpulse.Whenthecontrolpulseisturnedoff,theamplificationofthemiddlepulsereturnstoitsoriginallevel.theoutputlevelshouldnotbeaffectedafterthecontrolpulsehasbeenThisfractionalincreaseinprobeintensityΔI/I duetostimulatedemissionfromtheS1statewasmeasuredasafunctionofthetimedelaybetweenthepumpandprobepulsesusingalock-inamplifier.Withtheprobepulsemaintainedat3psafterthepumppulse,theeffectofthe100fscontrolpulseat800nmontheΔI/Isignalasafunctionofthecontrol-probetimedelaywasinvestigated.ThecontrolpulsescauseadecreaseoftheΔI/IsignalbecauseasubstantialpartoftheS1populationispushedtotheSnstate.AmplificationrecoversastherelaxestotheS1therecoveryinFig.4bcanbefittedtoabiexponentialdecayfunctionwithtimeconstantsofτ1=50fsandτ2=1ps.Thepreexponentialfactorsforthetwocomponentswere0.88and0.12,respectively.ThefastcomponentcanbeassignedtointernalconversionfromtheSntotheS1state.Inthisprocess,theelectronicSn←S1excitationenergyisconvertedintovibrationalenergy,whichsubsequentlyisdistributedoverallintramolecularvibrationalmodes.Someexcessenergystoredinopticallyactivevibrationalmodesisdissipatedonalongertimescalebyheattransfertounexcitedmoleculesandcanexplaina1pscomponentinthegainrecovery.theuseofthecopolymerhelpstoreducechargeseparationandtoachievefullgainrecovery.Ittakes2psforthegaintorecoverfully,therefore,thehighestpossibleswitchingrateforthiscopolymeris500GHz.偶氮苯分子的光致异构和超快全光开偶氮苯化合物含有的偶氮苯生色团具有顺反两种同分异构体。研究表明，反式)两个苯环式中心对称，在同一平面内；顺式()两个苯环在氮氮双键(--)的同一侧，而且是面对面的。偶氮苯在一定波长能够发生反式向顺式的转变。偶氮苯分子的基态为反式状态，通过光作用可使偶氮苯分子发生由反式向顺式的结构异构化转变，顺式通过热驰豫或受光照可重新转变为反式。在稳态条件下，顺式激发态一般通过热驰豫回到反式基态，由下图所示：偶氮苯光致异构的二能级系统模这两个异构体有完全不同的光学性质，导致光在两种异构态之间转换可对应于计算机的－转换过程。因此通过光学，可能实现基于光致异构的全关开关过程。2、偶氮苯聚合物和超快全光开①偶氮苯分子的光诱导各向异ExcitedstatePolarized偶氮苯光诱导各向异性原mCH2m

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NN(a(b) 国外类似材料dialkoxyazobenzenespiropyran-dopedPMMA单偶氮苯侧链聚合物双偶氮苯侧链聚合物:过程和很好的全光开关性能，光开关速度（～40ps）远有机光学双稳0年代起，得到了国内外的广泛研究。到目前为止，由无机半导体如Gas/GAs等制成的光双稳器件其开关速度已达纳秒或皮秒量级，进一步的研究希望获得具有高速度、低功耗、小尺寸和室温运转全光Ii是入射光强，It是透射光强，这种双稳曲线类似于磁滞特性，上图所示，对应一个入射光强Ii’,存在着两个透射光强It’It’’。在外界光脉冲的作用下，介质的非线性参数（非线性 三种细菌视紫红质分子基于饱和吸收的稳态无腔双稳态实验回线，）是由文献[4给出的结果，（）拟计算得到的曲线。献实果致，证明了我们的计算程序的正确性。在此基础上，我们计算了偶氮苯在稳态条件下基于饱和吸收的稳态无腔光学双稳态过程。下图计算了偶氮苯化合物在近吸收下的透射率随光强的变化关下图显示了不同K着K值增大，双稳态过程变得更加明显，当K＝0.3s-1，光学双稳态不同K

T增加双稳态过程的变化情况。结果表明，以往的研究表明，具有二维共轭体系的小分子卟啉化合物具有较大的三阶非线性极化率，但是，由于这类化合物的激发态较长，所以，光学响（1020ns种将卟啉发色团作为侧链基团的卟啉侧链聚合物P-PGM实验中作为参考也研究了小分子卟啉P的相应性能。

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0I IHTPP-HTPP-生物光子学，是由生命科学和物理科生物光子学主要以量子光学作为理论经典光场与生命现象之间的关系研究光子—生命体相互作用过程中场(自调节和自适应等)这两者之间的相互影探索人脑思维过程的特征、机理和规律发 等疑难病症的超快速光世界各国对这一交叉学科研究极为重视的科研相互交流和沟通，培养从事他发展了极为精巧的飞秒泵浦-探测技术研究了一系列从简单到复杂的化学和生物体系中各种类的化学反，包括单分子反应、双分反应和许生物过程的反应，包括异构化、解离、电子转移质子转移、分子 的弛豫过程等。他还从理论上对这过程进行计算和模拟，并给出了很的解释，而大大推进了人类对化学反应微观过程在深度和广度上的认识。的研究工使他获得1999年 由他组织的每二年一次的超快光子学DNA分子中的超快过程与DNA分子器件原1、引N作为一种重要的遗传物质，在生命过程中起着，传递和表达信息的重要作用。近几年来，关于的分子器件的研究引起了国内外的广泛关注。研究表明，分子器件在生命科学，信息科学和材料科学等领域都具有重要的应用前景。

最小距离（约100nm）内能海量信息。DN二级结构互变和碱基互补配对的分子得了很大的进展。2、DNA分子与金属配合物相互作用的稳态荧光性①中山大学计亮年教授等在研究一些钌等金属配合物（如103~104进一步的研究还显示②配合物的结构和构象对其荧光性能有着重要的（IhtshamulHaqetal.,J.Am.Chem.Soc.1995,117,4788-③DNA分子的构象的变化可导致配合物的荧光效率发生很大的变化B-form和Z-formDNA(NadrianC.SeemanetalNature1999,397,14, （Alan.Eetal.,Z-型3、DNA优点①与条纹相机比较条纹相机：时间分辨率：≧10ps(信号平均光谱响应：＜900nm（受光阴极响应限制）飞秒荧光上转换：时间分辨率：＜400fs(与飞秒脉冲相同)光谱响应：≦3.5µm(BBO晶体高灵敏度和绝对准确确定零点等特别适合有机和生物分子的荧光超快动力学的测②测定DNA和金属配合物的瞬态分子异构动力学过程诱导各向异性动