有機光電半導體材料及其未來之應用課件

1、有機光電半導體材料及其未來之應用 Institute of Electro-Optical Science and Engineering, National Cheng Kung University, Tainan, Taiwan 701成功大學 光電科學與工程研究所01/16/2007郭 宗 枋 助理教授T.-F. Guo1NCKU Institite of Electro-Optical Science & EngineeringOutlinesSemiconductors Organic semiconductors (energy and delocalization of cha

2、rge carriers)OLEDs and PLEDs 基礎原理和應用Organnic photovoltaic and solar cellsConclusionsT.-F. Guo2NCKU Institite of Electro-Optical Science & EngineeringFundamental science of inorganic semiconductorsT.-F. Guo3NCKU Institite of Electro-Optical Science & EngineeringTypical Semiconducting MaterialsT.-F. G

3、uo4NCKU Institite of Electro-Optical Science & EngineeringEnergy Band Diagram of a conductor, semiconductor, and insulator(a) a conductor(b) a semiconductor(c) an insulatorT.-F. Guo5NCKU Institite of Electro-Optical Science & EngineeringBeginning of orgnaic semiconductor ( bonding)Side-by-Side Bondi

4、ngT.-F. Guo6NCKU Institite of Electro-Optical Science & EngineeringConjugated (共軛): alternatively double-single bondsCHCHCHCHCHCH雙鍵單鍵 T.-F. Guo7NCKU Institite of Electro-Optical Science & EngineeringBang Gap of Polyacetylene.Band GapT.-F. Guo8NCKU Institite of Electro-Optical Science & EngineeringCo

5、njugated polymerSigma bondDelocalized electron cloudhttp:/www.cdtltd.co.ukAlternating single-double bondsT.-F. Guo9NCKU Institite of Electro-Optical Science & EngineeringCreating new materials from old materialsnEg = 2.4 eVPPVOR1nOEg = 2.1 eVR2R1nEg = 2.4 eVR2nEg = 3.0 eVPPPnEg = 1.4 eVPAThrough the

6、 structure engineering, polymers with different emitting colors were synthesized.T.-F. Guo10NCKU Institite of Electro-Optical Science & EngineeringDelocalization of Charge Carriers in PolyacetyleneLocalized! Charge cannot go anywhere!Delocalized! Charge carriers can move around!T.-F. Guo11NCKU Insti

7、tite of Electro-Optical Science & EngineeringDelocalization and Transport of Charge CarriersT.-F. Guo12NCKU Institite of Electro-Optical Science & EngineeringConjugated Polymers: Basic Materials and ChemistryConduction polymers: Polyacetylene, Polyaniline, PEDOT/PSS etc.Semiconducting polymers: Poly

8、thiophenes, Oligothiophenes etc.Light-emitting/Photovoltaic Polymers: Poly-(para-phenylene-vinylene), Poly(para-phenylene), Polyfluorene etc. T.-F. Guo13NCKU Institite of Electro-Optical Science & EngineeringScientific Interest in Organic Materials1950s steady work on crystalline organics starts1970

9、s organic photoconductors (Xerography)1980s organic non-linear optical materials1987 Kodak first published the efficient organic light-emitting devices (OLED)1990 Cambridge groups publish the first polymer light-emitting diodes (PLED)Since then, the field has dramatically expanded both commercially

10、and scientifically, including OLED, PLED, transistors, potovoltaic, solar cells T.-F. Guo14NCKU Institite of Electro-Optical Science & EngineeringWhat are the OLEDs?Invented by Dr. Ching W Tang （鄧青雲(yún)博士）(kodak) 1987年OLED 全名叫做有機發(fā)光二極體 (Organic Light-Emitting Diode)部分國外又稱 OEL為有機電激光顯示 (Organic Electrolumi

11、nescence Display) T.-F. Guo15NCKU Institite of Electro-Optical Science & EngineeringOLED 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(fā)光層- Emitting Layer (EML) T.-F. Guo16NCKU Institite of Electro-Optical Science & E

12、ngineeringFirst OLED Invented by Dr. Ching W Tang (kodak) 1987T.-F. Guo17NCKU Institite of Electro-Optical Science & EngineeringAbsorption, Fluorescence & Phosphorescence ProcessT.-F. Guo18NCKU Institite of Electro-Optical Science & EngineeringSinglet excitonsTriplet excitonsh1h2fluorescencenon-radi

13、ationheate-/h+dissociationrecombinationIntersystem crossingT-T annihilationphosphorescencedissociationcarrier separationcarrier injectionPhotophysics processground stateT.-F. Guo19NCKU Institite of Electro-Optical Science & EngineeringOperation of OLEDsGlass or PET substrateITOETLHTL+_+_+_+CathodeAn

14、odeT.-F. Guo20NCKU Institite of Electro-Optical Science & EngineeringElectroluminescence of O/PLEDSingle layer deviceDouble layer devicePLEDDouble layer deviceOLEDT.-F. Guo21NCKU Institite of Electro-Optical Science & Engineering221/1/Mechanism of ElectroluminescenceT.-F. Guo22NCKU Institite of Elec

15、tro-Optical Science & EngineeringIntersystem crossing (ISC)S0S1T1Ground stateFluorescencePhosphorescenceFluorescence and PhosphorescenceDecay from singlet allowed by symmetry: fast and often efficient.Decay from triplet disallowed by symmetry: slow and usually inefficient.25%75%Singlet excitonTriple

16、t excitonT.-F. Guo23NCKU Institite of Electro-Optical Science & EngineeringDevice preparationITO/Glass substrateOrganic materialsVacuum10-5 torrLecture note of Prof. Chou, NTU Phys.T.-F. Guo24NCKU Institite of Electro-Optical Science & EngineeringWhat are PLEDs?Invented by Richard. H. Friend (Univer

17、sity of Cambridge, Cavendish Laboratory) 1990年PLED 全名叫做高分子發(fā)光二極體 (Polymer Light-Emitting Diode)Usually for single layer device configurationT.-F. Guo25NCKU Institite of Electro-Optical Science & EngineeringFirst PLED Invented by Richard. H. Friend (Cambridge University, Cavendish Laboratory)1990They

18、used Al as the cathode material at that time.T.-F. Guo26NCKU Institite of Electro-Optical Science & EngineeringSynthetic 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. Guo27NCKU Institite

19、 of Electro-Optical Science & EngineeringSchematic Energy Level Diagram T.-F. Guo28NCKU Institite of Electro-Optical Science & EngineeringProcessing for the fabrication of a typical PLEDPre-cleaned ITO/glass substrateSpin coating PEDOT layer & baking*OO*n Eg=2.1eVOrange-redor yellowMEH-PPVSpin coati

20、ng MEH-PPV layer & bakingCathode depositionPEDOT:PSST.-F. Guo29NCKU Institite of Electro-Optical Science & EngineeringPLED Devices at NCKUBefore biasBiased deviceT.-F. Guo30NCKU Institite of Electro-Optical Science & EngineeringWhy they are so important?http:/www.nobel.se/chemistry/laureates/2000/il

21、lpres/7.htmlSelf-luminescentNo viewing angle limitationThin, Light weightLow operation voltageFlexible substrate applicationT.-F. Guo31NCKU Institite of Electro-Optical Science & Engineering20 inches, amorphous Si, active matrix, full color OLED displayWXGA (1280 x 768 pixels), 25 W, 300 cd/m2, CMO

22、03/12/2003Recent progress of EL PanelsKodak digital camera, available on April 2003Ink-jet printed EL display, Toshiba and Epson 2002T.-F. Guo32NCKU Institite of Electro-Optical Science & EngineeringReasons for organic solar cellsOrganic solar cells: moderate efficiencies and very low cost Inorganic

23、 photovoltaic cellS.E. Shaheen, D.S. Ginley, G.E. Jabbour, Mrs. Bull., 30, pp.10-18(2005).T.-F. Guo33NCKU Institite of Electro-Optical Science & EngineeringA Flexible, printed plastic solar cell with high efficiency made by SIMENS AGhFlexible Donor-acceptor type solar cellsT.-F. Guo34NCKU Institite of Electro-Optical Science & EngineeringWorking principle of organic solar cellA Donor - Acceptor type bulk heterojunction solar cellMeta