Triphenylene-based Polymers for Organic Electronics Dissertation zur Erlangung des Grades “Doktor der Naturwissenschaften” am Fachbereich Chemie, Pharmazie und Geowissenchaften der Johannes Gutenberg-Universität Mainz vorgelegt von Moussa Saleh geboren in Tripolis, Libyen Mainz, 2010 II Table of contents Chapter 1. Foreword................................................................................................................ 1 1.1 Background on -Conjugated Polymers .................................................................... 3 1.2 Poly(para-phenylene)-Type Polymers as Blue-emitters............................................. 5 1.3 Synthetic Approaches to Poly(para-Phenylene)- Type Polymers .............................. 6 1.3.1 Oxidative condensation of aromatic hydrocarbons............................................ 7 1.3.2 Transition metal-mediated coupling reactions ................................................... 9 1.4 Organic Light Emitting Diodes ................................................................................ 18 1.4.1 Electroluminescence......................................................................................... 19 1.4.2 Basic processes and parameters in electroluminescent devices ....................... 19 1.4.3 Multilayer PLED devices ................................................................................. 23 1.5 General motivation................................................................................................... 25 1.6 References ................................................................................................................ 31 Chapter 2. Triphenylene-Based Conjugated Polymers for Blue Polymeric Light Emitting Diodes .................................................................................................................. 40 2.1 Introduction .............................................................................................................. 40 2.2 Synthesis and characterization of conjugated polytriphenylenes............................. 44 2.2.1 Monomer synthesis........................................................................................... 44 2.2.2 Polymer synthesis............................................................................................. 48 2.3 Photophysical properties of triphenylene-based monomers and polymers.............. 55 2.3.1 Absorption and photoluminescence of triphenylene monomers ...................... 55 2.3.2 Optical properties of triphenylene-based polymers.......................................... 58 2.4 Electrochemical properties of triphenylene-based polymers ................................... 67 2.5 Thermogravimetric analysis (TGA) ......................................................................... 69 2.6 Supramolecular organization of triphenylene-based polymers................................ 70 2.6.1 Supramolecular organization of triphenylene-alt-arylene copolymers ............ 73 2.6.2 Supramolecular organization of polytriphenylene homopolymers .................. 76 2.7 Application of triphenylene-based polymers in polymeric light emitting diodes .... 78 2.8 Conclusions .............................................................................................................. 88 2.9 References ................................................................................................................ 91 Chapter 3. Triphenylene-Pyrene, Triphenylene-Fluorene, and Triphenylene-Carbazole- based Copolymers for OLED applications ...................................................... 97 3.1 Introduction .............................................................................................................. 97 3.2 Triphenylene-Pyrene copolymer (P10)...................................................................... 99 III 3.2.1 Synthesis and characterization ......................................................................... 99 3.2.2 Photophysical properties of polymer P10........................................................ 101 3.2.3 Electrochemical properties of polymer P10 .................................................... 106 3.2.4 Application of Triphenylene-Pyrene co-polymer (P10) in blue PLEDs ......... 108 3.3 Triphenylene-Fluorene co-polymers (P11 and P12)................................................. 112 3.3.1 Synthesis and Characterizations..................................................................... 112 3.3.2 Photophysical properties of polymers P11 and P12.......................................... 113 3.3.3 Electrochemical properties of polymers P11 and P12 ...................................... 118 3.3.4 Differential scanning calorimetry (DSC) ....................................................... 119 3.3.5 Thermogravimetric analysis (TGA) ............................................................... 120 3.3.6 Supramolecular organization of polymers P11 and P12 ................................... 121 3.3.7 Application of Triphenylene-Fluorene co-polymers (P11 and P12) in polymeric light emitting diodes....................................................................................... 124 3.4 Triphenylene-Carbazole co-polymer (P13) ............................................................. 131 3.4.1 Synthesis and characterization ....................................................................... 131 3.4.2 Photophysical properties of polymer P13........................................................ 132 3.4.3 Electrochemical properties of polymer P13 .................................................... 136 3.4.4 Differential scanning calorimetry................................................................... 137 3.4.5 Thermogravimetric analysis........................................................................... 138 3.4.6 Supramolecular organization of polymer (P13) .............................................. 139 3.5 Conclusions ............................................................................................................ 143 3.6 References ................................................................................................................ 146 Chapter 4. From Triphenylene-based Polymers to Graphene Nanoribbons.................. 148 4.1 Introduction ............................................................................................................ 148 4.2 Synthesis of GNRs using Scholl reaction conditions............................................. 152 4.2.1 Synthesis of 6,11-Bis-(4-tert-butyl-phenyl)-1,2,3,4-tetraphenyl-triphenylene (model compound) ......................................................................................... 152 4.2.2 Synthesis of GNR-20...................................................................................... 156 4.2.3 Synthesis of GNR-21...................................................................................... 160 4.2.4 Synthesis of GNR-22...................................................................................... 165 4.2.5 Micro-Raman analysis.................................................................................... 168 4.3 Surface-mediated GNRs synthesis ......................................................................... 175 4.3.1 Synthesis of precursor monomers .................................................................. 176 4.3.2 Synthesis of GNRs ......................................................................................... 178 IV 4.4 References .............................................................................................................. 185 Chapter 5. Outlook and Conclusion Remarks................................................................... 189 Chapter 6. Experimental Section........................................................................................ 194 Publication ............................................................................................................................ 223 V Index of Abbreviations CIE Commission Internationale de L’Eclairage DCM dichloromethane DSC differential scanning calorimetry EL electroluminescence ETL electron transporting layer FD MS field desorption mass spectroscopy FRET Forster resonance energy transfer GPC Gel permeation chromatography h hour HBC hexa-peri-hexabenzocoronene HBL hole blocking layer HOMO highest occupied molecular orbital ITO indium tin oxide I-V-L current density and luminescence versus voltage LUMO lowest unoccupied molecular orbital MALDI-TOF matrix-assisted laser desorption ionization –time of flight MeOH methanol min minute MS mass spectroscopy NMR nuclear magnetic resonance OLED organic light emitting diode PAH polycyclic aromatic hydrocarbons PEDOT:PSS poly(styrene sulphonic ester) doped poly(ethylenedioxy- thiophene) VI PF polyfluorene PL photoluminescence PLED Polymeric light emitting diode RGB red, green, and blue RT room temperature STM scanning tunneling microscopy TBAF tetrabutylammonium fluoride TCNQ 7,7,8,8-tetracyanoquinodimethane TGA thermogravimetric analysis THF tetrahydrofuran UV-vis ultraviolet/visible WAXS wide angle X-ray scattering VII Chapter 1 Chapter 1 Foreword With the invention of the transistor around the middle of the 20th century, inorganic semiconductors like silicon started to take over the role as principal materials in electronics from the before customary metals. By more development in the field of semiconductors, inorganic based microelectronics became ubiquitous in our everyday life by the end