Novel thieno[3,4-b]pyrazine based {π-conjugated [pi-conjugated] polymers for optoelectronic devices [Elektronische Ressource] / von Munazza Shahid

Novel Thieno[3,4-b]pyrazine Based π-Conjugated
Polymers For Optoelectronic Devices



Dissertation



Zur Erlangung des akademischen Grades
doctor rerum naturalium (Dr. rer. nat.)



vorgelegt dem Rat der Chemisch-Geowissenschaftlichen Fakultät
der Friedrich-Schiller-Universität Jena



von M.Sc. M.Phil Munazza Shahid
geboren am 26.01.1975 in Sargodha






Jena, August 2006










































Gutachter:
1. Prof. Dr. E. Klemm
2. Prof. Dr. U. Scherf
Tag der öffentlichen Verteidigung: 25-10-2006 Contents i(ii)
Contents

1 Introduction...................................................................................................................... 1
1.1 Motivation.3
1.1.1 Fossil Fuels.........................................................................................................3
1.1.2 Renewable Energy..............................................................................................
1.1.3 Plastic Solar Cells............................................................................................... 3
1.1.4 Thieno[3,4-b]pyrazine, A promising material for optoelectronic devices ......... 9
2 General Part... 11
2.1 Horner–Wadsworth–Emmons reaction (HWE).................................................... 11
2.2 Knoevenagel condensation......................................................................................13
2.3 Gilch Reaction.........................................................................................................15
2.4 Suzuki Cross-Coupling............................................................................................17
2.5 Basics of Polycondensation..................................................................................... 20
3 Results and Discussion................................................................................................... 22
3.1 Pi-conjugated polymers containing thieno[3,4-b]pyrazine unit incorporated in
backbone chain.................................................................................................................... 22
3.1.1 Synthesis and Characterization of Monomers and Model Compounds ........... 22
3.1.2 Synthesis and Characterization of Polymers.................................................... 31
3.1.3 Optical Properties of Monomers and Model Compounds................................ 36
3.1.4 roperties of Polymers ........................................................................ 39
3.1.5 Thermal Annealing Effect of P-1, P-2 and P-5 Films. ..................................... 44
3.1.6 Aggregate Formation in Solvent/Nonsolvent Solution .................................... 46
3.1.7 Electrochemical Studies of Model Compounds and Polymers ........................ 48
3.1.8 Photovoltaic Properties of Polymers P-1, P-2 and P-5 52
3.2 Pi- conjugated polymers containing thieno[3,4-b]pyrazine as pendant group..... 58
3.2.1 Synthesis and Characterization of Monomers and Model Compounds ........... 58
3.2.2 Synthesis of Polymers ...................................................................................... 63
3.2.3 Characterization of Polymers ........................................................................... 67
3.2.4 FT-IR Analysis.................................................................................................70
3.2.5 Optical Properties.............................................................................................71
3.2.6 Thermal Annealing Effect of P-10 and P-17 Films.......................................... 76
3.2.7 Electrochemical Studies...................................................................................78
4 Experimental................................................................................................................... 81
4.1 Instrumentation.......................................................................................................81
4.2 Pi-conjugated polymers containing thieno[3,4-b]pyrazine unit incorporated in
backbone chain.................................................................................................................... 83
4.2.1 Synthesis of Monomer Precursors.................................................................... 83
4.2.2 Monomers Synthesis........................................................................................87
4.2.3 Model Compounds Synthesis........................................................................... 89
4.2.4 Synthesis of Polymers ...................................................................................... 90
4.3 Pi- conjugated polymers containing thieno[3,4-b]pyrazine as pendant group..... 94
4.3.1 Monomer Precursors 94
4.3.2 Monomers Synthesis96
4.3.3 99
4.3.4 Synthesis of Polymers .................................................................................... 100
5 Zusammenfassung in Thesen 105
6 References..................................................................................................................... 110
7 Appendix....................................................................................................................... 118
1 137.1 H and C NMR Spectra ..................................................................................... 118 Contents ii(ii)
7.2 Molecular Formulae.............................................................................................128
7.3 Abbreviations.........................................................................................................132
Curriculum Vitae ................................................................................................................. 134
List of Publications............................................................................................................... 135
Acknowledgement ................................................................................................................ 136
Selbständigkeitserklärung................................................................................................... 138







1. Introduction 1(138)
1 Introduction
1Conjugated polymers have attracted considerable attention as a new class of electronic
material, since the study of these systems has generated entirely new scientific concepts as
well as potential for new technology. Conjugated polymers are organic semiconductors and as
such important materials for applications in electronic and photonic devices. Prime examples
2 3 4are polymeric light-emitting diodes, plastic lasers, and polymer-based photovoltaic cells,
5but at least in principle, conjugated polymers should be able to pertain all of the functions an
6inorganic semiconductor displays, FETs, and may lead in the future to "molecular
7electronics". The primary advantage of organic polymers over their inorganic counterparts is
8their ease of processing by dip coating, spin casting, printing, or use of doctor blade
techniques. However, conjugated polymers are likewise important as sensory materials for
water, organic vapors, and explosives either by fluorescence quenching or in artificial nose
9devices, which change their conductivity upon exposure to a suitable analyte.
The goal with organics-based devices is not necessarily to attain or exceed the level of
performance of inorganic semiconductor technologies (silicon is still the best at the many
things that it does) but to benefit from a unique set of characteristics combining the electrical
properties of (semi)conductors with the properties typical of plastics, that is, low cost,
versatility of chemical synthesis, ease of processing, and flexibility. Interest in conjugated
polymers picked up significantly after the 1976 discovery that they can be made highly
10electrically conducting following a redox chemical treatment. This discovery led to the 2000
Nobel Prize in Chemistry awarded to Alan Heeger, Alan MacDiarmid, and Hideki Shirakawa.
By the mid-eighties, many research teams in both academia and industry were investigating -
conjugated oligomers and polymers for their nonlinear optical properties or their
semiconducting properties, paving the way to the emergence of the fields of plastic <