Band gap engineering of donor-acceptor {π-conjugated [pi-conjugated] poly(heteroarylene)s and poly(heteroaryleneethynylene)s [Elektronische Ressource] / von Raja Shahid Ashraf

Band Gap Engineering of Donor-Acceptor
π-Conjugated Poly(heteroarylene)s and
Poly(heteroaryleneethynylene)s



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 Raja Shahid Ashraf
geboren am 24.01.1976 in Gujrat






Jena, May 2005









































Gutachter:
1. Prof. Dr. E. Klemm
2. PD Dr. M. Thelakkat
Tag der öffentlichen Verteidigung: 29-06-2005

Content i (iii)
Content

1 Introduction.........................................................................................................................1
1.1 π-Conjugated Polymers........................................................................................................... 1
1.2 Band Gap Engineering of π-Conjugated Polymers ................................................................. 3
1.3 Donor–Acceptor π-Conjugated Polymers ............................................................................... 3
2 General Part........................................................................................................................9
2.1 Mechanism of Sonogashira Cross-Coupling........................................................................... 9
2.2 of Suzuki Cross-Coupling ................................................................................. 12
2.3 Basics of Polycondensation................................................................................................... 15
3 Results and Discussion.....................................................................................17
3.1 Monomer Synthesis ............................................................................................................ 17
3.1.1 Diethynyl Monomers....................................................................................................17
3.1.1.1 2,5-Diethynyl Alkyl Substituted Thiophenes................................................................. 17
3.1.1.2 1,4-Diethynyl-2,5-Dialkoxy Substituted Phenylenes.................................................... 18
3.1.2 Dibromo Monomers ..................................................................................................... 18
3.1.3 Dioxaborolane Monomers............................................................................................ 21
3.2 Benzothiadiazole and Thiophene Based Poly(heteroaryleneethynylene)s ................... 23
3.2.1 Synthesis and Characterization of the Polymers.......................................................... 23
3.2.2 Optical Properties ........................................................................................................ 26
3.2.3 Aggregate Formation in Solvent/Nonsolvent Solution................................................. 28
3.2.4 Electrochemical Studies ............................................................................................... 30
3.2.5 Photovoltaic Studies..................................................................................................... 32
3.3 Quinoxaline and Thiophene Based Poly(heteroaryleneethynylene)s ............................ 35
3.3.1 Synthesis and Characterization of the Polymers.......................................................... 35
3.3.2 Optical Properties.. 39
3.3.3 Aggregate Formation in Solvent/Nonsolvent Solution................................................. 41
3.3.4 Electrochemical Studies ............................................................................................... 45
3.4 Thienopyrazine Based Low Band Gap Poly(heteroaryleneethynylene)s...................... 47
3.4.1 Synthesis and Characterization of the Polymers.......................................................... 47
3.4.2 Optical Properties ........................................................................................................ 51
3.4.3 Aggregate Formation in Solvent/Nonsolvent Solution................................................. 53
3.4.4 Electrochemical Studies 54

Content ii (iii)
3.5 PE/PPV Hybrid Polymers ................................................................................................. 56
3.5.1 Synthesis and Characterization of the Polymers.......................................................... 56
3.5.2 Optical Properties ........................................................................................................ 59
3.5.3 Electrochemical Studies ............................................................................................... 62
3.6 Thienopyrazine and Fluorene Based Poly(heteroarylene)s............................................ 64
3.6.1 Synthesis and Characterization.................................................................................... 64
3.6.2 Optical Properties.. 69
3.6.3 Aggregate Formation in Solvent/Nonsolvent Solution................................................. 70
3.6.4 Stability of the Polymers .............................................................................................. 71
3.6.5 Electrochemical Studies ............................................................................................... 72
3.7 Quinoxaline and Fluorene Based Poly(heteroarylene)s.................................................. 74
3.7.1 Synthesis and Characterization 74
3.7.2 Optical Properties ........................................................................................................ 77
3.7.3 Aggregate Formation in Solvent/Nonsolvent Solution................................................. 79
3.7.4 Electrochemical Studies 80
3.7.5 Photophysical Properties of Binary Blends of the Polymers P-14 and P-19............... 81
4 Experimental.................................................................................................................... 84
4.1 Instrumentation..................................................................................................................... 84
4.2 Synthesis: (Synthesis of Monomer Precursors) ................................................................... 86
4.3 Monomers Synthesis............................................................................................................ 93
4.4 Synthesis of Polymers .......................................................................................................... 99
5 Zusammenfassung in Thesen ................................................................................... 106
6 References ....................................................................................................................... 113
7 Appendix ......................................................................................................................... 124
137.1 C-NMR Spectra ............................................................................................................... 124
7.2 Molecular Formulae........................................................................................................... 133
7.3 Abbreviations..................................................................................................................... 136
Curriculum Vitae ................................................................................................................. 138
List of Publications .............................................................................................................. 139
Acknowledgement ................................................................................................................ 140
Selbständigkeitserkärung.................................................................................................. 141




Content iii (iii)












This thesis consists of: 141 Pages
90 Figures
24 Tables
28 Schemes

















1. Introduction 1 (141)
1 Introduction

1.1 π-Conjugated Polymers

1The emergence of conjugated polymers as a new class of electronic materials, has attracted
considerable attention, since the study of these systems has generated entirely new scientific
concepts as well as potential for new technology. Conjugated polymers are organic
semiconductors