有机光电半导体材料及其未来之应用

1、会计学1有机光电半导体材料及其未来之应用有机光电半导体材料及其未来之应用T.-F. Guo2T.-F. Guo3Fundamental science of inorganic semiconductorsT.-F. Guo4Typical Semiconducting MaterialsT.-F. Guo5(a) a conductor(b) a semiconductor(c) an insulatorT.-F. Guo6Beginning of orgnaic semiconductor ( bonding)Side-by-Side BondingT.-F. Guo7Conjugated

2、 (共軛共軛): alternatively double-single bondsCHCHCHCHCHCHCHHCCHHCCHHCCHHCCHHCCHHCCHHCC雙鍵雙鍵單鍵單鍵 T.-F. Guo8.Band GapT.-F. Guo9Conjugated polymerSigma bondDelocalized electron cloudhttp:/www.cdtltd.co.ukAlternating single-double bondsT.-F. Guo10Creating new materials from old materialsnEg = 2.4 eVPPVOR1nO

3、Eg = 2.1 eVR2R1nEg = 2.4 eVR2nEg = 3.0 eVPPPnEg = 1.4 eVPAThrough the structure engineering, polymers with different emitting colors were synthesized.T.-F. Guo11Delocalization of Charge Carriers in PolyacetyleneLocalized! Charge cannot go anywhere!Delocalized! Charge carriers can move around!T.-F. G

4、uo12Delocalization and Transport of Charge CarriersT.-F. Guo13Conjugated Polymers: Basic Materials and Chemistry Conduction polymers: Polyacetylene, Polyaniline, PEDOT/PSS etc. Semiconducting polymers: Polythiophenes, Oligothiophenes etc. Light-emitting/Photovoltaic Polymers: Poly-(para-phenylene-vi

5、nylene), Poly(para-phenylene), Polyfluorene etc. T.-F. Guo14Scientific Interest in Organic Materials 1950s steady work on crystalline organics starts 1970s organic photoconductors (Xerography) 1980s organic non-linear optical materials 1987 Kodak first published the efficient organic light-emitting

6、devices (OLED) 1990 Cambridge groups publish the first polymer light-emitting diodes (PLED) Since then, the field has dramatically expanded both commercially and scientifically, including OLED, PLED, transistors, potovoltaic, solar cells T.-F. Guo15What are the OLEDs?Invented by Dr. Ching W Tang （鄧青

7、雲博士）(kodak) 1987年OLED 全名叫做有機發光二極體 (Organic Light-Emitting Diode)部分國外又稱 OEL為有機電激光顯示 (Organic Electroluminescence Display) T.-F. Guo16OLED Basic Device ConfigurationDouble layers structure 電洞傳輸層-Hole Transport (injection) Layer (HTL) 電子傳輸層 Electron Transport Layer (ETL) 發光層- Emitting Layer (EML) T.-F.

8、 Guo17First OLED Invented by Dr. Ching W Tang (kodak) 1987T.-F. Guo18Absorption, Fluorescence & Phosphorescence ProcessT.-F. Guo19Singlet excitonsTriplet excitonsh1h2fluorescencenon-radiationheate-/h+dissociationrecombinationIntersystem crossingT-T annihilationphosphorescencedissociationcarrier

9、separationcarrier injectionPhotophysics processground stateT.-F. Guo20Operation of OLEDsGlass or PET substrateITOETLHTL+_+_+ +_ _+CathodeAnodeT.-F. Guo21Electroluminescence of O/PLEDSingle layer deviceDouble layer devicePLEDDouble layer deviceOLEDT.-F. Guo22carrierinjectioncarriermigration(+)(-)(+)(

10、-)(+)(-)221/+-3 symmetric statesTriplets1 antisymmetric stateSinglet1/+orsinglettriplethole (+)electron (-)exciton (*)Mechanism of ElectroluminescenceT.-F. Guo23Intersystem crossing (ISC)S0S1T1Ground stateFluorescencePhosphorescenceFluorescence and PhosphorescenceDecay from singlet allowed by symmet

11、ry: fast and often efficient.Decay from triplet disallowed by symmetry: slow and usually inefficient.25%75%Singlet excitonTriplet excitonT.-F. Guo24Device preparationITO/Glass substrateOrganic materialsVacuum10-5 torrLecture note of Prof. Chou, NTU Phys.T.-F. Guo25What are PLEDs?Invented by Richard.

12、 H. Friend (University of Cambridge, Cavendish Laboratory) 1990年PLED 全名叫做高分子發光二極體 (Polymer Light-Emitting Diode)Usually for single layer device configurationT.-F. Guo26First PLED Invented by Richard. H. Friend (Cambridge University, Cavendish Laboratory)1990They used Al as the cathode material at th

13、at time.T.-F. Guo27Synthetic Route to PPVJ. H. Burroughes, D. D. C. Bradley, A. R. Brown, R. N. Marks, K. Mackay, R. H. Friend, P. L. Burns, and A. B. Holmes, Nature, 347, 539 (1990).T.-F. Guo28Schematic Energy Level Diagram T.-F. Guo29Processing for the fabrication of a typical PLEDPre-cleaned ITO/

14、glass substrateSpin coating PEDOT layer & baking*OO*n Eg=2.1eVOrange-redor yellowMEH-PPVSpin coating MEH-PPV layer & bakingCathode depositionOOSSOOOOSSOOOOSn+SO3-nSO3HmPEDOT:PSST.-F. Guo30PLED Devices at NCKUBefore biasBiased deviceT.-F. Guo31Why they are so important?http:/www.nobel.se/chem

15、istry/laureates/2000/illpres/7.htmlSelf-luminescentNo viewing angle limitationThin, Light weightLow operation voltageFlexible substrate applicationT.-F. Guo3220 inches, amorphous Si, active matrix, full color OLED displayWXGA (1280 x 768 pixels), 25 W, 300 cd/m2, CMO 03/12/2003Recent progress of EL

16、PanelsKodak digital camera, available on April 2003Ink-jet printed EL display, Toshiba and Epson 2002T.-F. Guo33Reasons for organic solar cellsOrganic solar cells: moderate efficiencies and very low cost Inorganic photovoltaic cellS.E. Shaheen, D.S. Ginley, G.E. Jabbour, Mrs. Bull., 30, pp.10-18(200

17、5).T.-F. Guo34A Flexible, printed plastic solar cell with high efficiency made by SIMENS AGhFlexible Donor-acceptor type solar cellsT.-F. Guo35Working principle of organic solar cellA Donor - Acceptor type bulk heterojunction solar cellMetal electrode(Al, Ca/Al etc.)he-h+EFHOMO PCBMLUMO AcceptorLUMO

18、 DonorHOMO DonorITO/PEDOTe-h+h+h+e-Donor + AcceptorMetal electrodeITOhOCH2OSSSSn/4Donor-P3HTAcceptor-PCBMMPPMPPocscFFVJVJscocoutpowerininFFJVPPPJ (photo-current density) V (Bias) curves for devices with Al and Ca/Al as the cathodes CathodematerialVoc(V)Jsc(mA/cm2)Vmpp(V)Jmpp(mA/cm2)Fill FactorpowerA

19、l0.564-8.1530.426-3.6910.4232.142%Ca/Al0.544-12.9330.382-10.4330.5664.383%Incident power of 90mW/cm2T.-F. Guo37T.-F. Guo38Future of Information DisplayT.-F. Guo39Conjugated (共軛共軛): alternatively double-single bondsCHCHCHCHCHCHCHHCCHHCCHHCCHHCCHHCCHHCCHHCC雙鍵雙鍵單鍵單鍵 T.-F. Guo40Electroluminescence of O/PLEDSingle layer deviceDouble layer devicePLEDDouble layer deviceOLEDT.-F. Guo41carrierinjectioncarriermigration(+)(-)(+)(-)(+)(-)22