On the correlation between the electronic structure and transport properties of [2.2]paracyclophanes and other aromatic systems [Elektronische Ressource] / Johannes Pfister. Betreuer: Bernd Engels

Ak Engels

Informations

• Publié par: julius-maximilians-universitat_wurzburg
• Publié le: 01 janvier 2011
• Nombre de lectures: 23
• Langue: Deutsch
• Poids de l'ouvrage: 5 Mo

Extrait

Julius-Maximimilians-Universität Würzburg
Fakultät für Chemie und Pharmazie




On the correlation between the
electronic structure and transport
properties of [2.2]paracyclophanes
and other aromatic systems

Dissertation zur Erlangung des
naturwissenschaftlichen Doktorgrads der
Julius-Maximilians-Universität Würzburg


vorgelegt von
Johannes Pfister


Würzburg 2011

Eingereicht am: ____________________________________________________
bei der Fakultät für Chemie und Phamrazie.


1. Gutachter: ____________________________________________________
2. Gutachter: ____________________________________________________
der Dissertation


1. Prüfer: ____________________________________________________
2. Prüfer: ____________________________________________________
3. Prüfer: ____________________________________________________
des öffentlichen Promotionskolloquiums.


Tag des öffentlichen Promotionskolloquiums: _________________________________


Doktorurkunde ausgehändigt am: __________________________________________
Table of Contents

Chapter 1 Introduction .............................................................................................. 1
Chapter 2 Model Concepts and Background .......................................................... 6
2.1 Transport in Organic Materials ................................................................... 6
2.1.1 Fermi´s Golden Rule ..................................................................... 6
2.1.2 Franck-Condon Principle ............................................................. 10
2.1.2.1 Simulation of REMPI Spectra ......................................... 14
2.1.3 Marcus-Hush Theory ................................................................... 15
2.1.3.1 Derivation of the Semi-Classical Marcus Rate Equation 19
2.1.3.2 Calculation of the Reorganization Energy ...................... 21
2.2 Exciton Transport ..................................................................................... 22
2.2.1 Exciton Theory............................................................................. 22
2.2.1.1 Frenkel Exciton ............................................................. 23
2.2.1.2 Mott-Wannier Exciton ................................................... 24
2.2.1.3 Davydov Exciton ........................................................... 25
2.2.2 Davydov Splitting ......................................................................... 25
2.3 Charge Transport ..................................................................................... 28
2.4 Diffusion ................................................................................................... 29
2.5 Band Transport ........................................................................................ 35
Chapter 3 Calculation of the Electronic Coupling Parameter – Concepts .......... 39
3.1 Exciton Transport ..................................................................................... 37
3.1.1 Förster Theory ............................................................................. 37 3.1.2 Dexter Transport .......................................................................... 39
3.1.3 Monomer Transition Density Approach ....................................... 40
3.1.4 Supermolecular Approach ........................................................... 42
3.2 Charge Transport ..................................................................................... 45
3.2.1 Energy Splitting in Dimer ............................................................. 45
3.2.2 T w o-State Model ......................................................................... 46
Chapter 4 Exciton and Charge Transport Properties in Weakly Interacting
Systems .................................................................................................. 49
4.1 Exciton Transport in Anthracene .............................................................. 49
4.2 Charge Transport in Perylene .................................................................. 54
4.2.1 Hole Transport ............................................................................. 56
4.2.2 Electron Transport ....................................................................... 58
Chapter 5 [2.2]Paracyclophanes as Strongly Interacting π-Systems ................. 61
5.1 Structural Features of [2.2]Paracyclophanes and Derivates .................... 61
5.2 Experiments ............................................................................................. 63
5.2.1 Synthesis and Crystal Structure Determination ........................... 63
5.2.2 Experimental Setup of the [1+1]REMPI-Spectra ......................... 64
5.3 Computational Details .............................................................................. 65
5.4 Ground State Structures .......................................................................... 66
5.4.1 Different Approaches in Comparison ........................................... 66
5.4.2 Rotamers in Hydroxy-Substituted [2.2]Paracyclophanes ............. 69
5.4.3 Two Dimernsional Ground State Potential Energy Plots ............. 70
5.5 Excited State Structures ........................................................................... 72 5.6 Analysis of Ground and Excited State Structures ..................................... 73
5.6.1 HOMO and LUMO Orbitals .......................................................... 73
5.6.2 Electrostatic Potential .................................................................. 74
5.7 Adiabatic Excitation Energies ................................................................... 77
5.7.1 Finding the Appropriate Method .................................................. 77
5.7.2 Zero-Point Vibrational Energies ................................................... 79
5.8 [1+1]REMPI Spectra ................................................................................ 81
5.8.1 o-DHPC ..................................................................................... 83
5.8.2 p-DHPC ..................................................................................... 86
5.8.3 MHPC ..................................................................................... 89
Chapter 6 Summary ................................................................................................. 95
Chapter 7 Zusammenfassung .................................................................................... 97
Chapter 8 References and Notes ............................................................................ 100
Chapter 9 Appendix................................................................................................... 107 1. Introduction
The world´s thirst for electrical power grows steadily. The United States Energy
Information Administration (EIA) predicts an increase of energy consumption by 49%
18 18 1from 522·10 J in 2007 to 780·10 J in 2035 (see figure 1.1). New sources of
energy have to be found and existing technologies must be improved to sustain this
need of energy. Figure 1.2 contains the 2010 annual report of The Renewable
st 2Energy Policy Network for the 21 Century. 2010 78% of the consumed energy was
provided by fossil fuels, a limited resource. 2.8% w as produced by nuclear energy
and 19% by renewable energy sources. It is important to mention that 68% of the
energy consumption counted as “renewable” w a s traditional biomass (plant and
3animal matter) for heat and cooking fire in developing regions. Only 0.7% of these
19% renewable energy, a very small amount, was produced by wind, solar, biomass
and geothermal power plants. Since fossil fuels are limited and rapidly decreasing
18mankind needs other sources. One possibility is the sun. In one year 3,850,000·10
J of energy is absorbed by our planet. Less than 1‰ is used in photosynthesis.
Simply put, one year of solar radiation is more energy for the earth than twice



Figure 1.1 Worldwide energy consumption for the last 20 years and future
projections. Source: U.S. Energy Information Administration (EIA).
1

3Figure 1.2 Renewable energy share of global energy consumption 2008.
than twice the amount provided by all the planet´s reserves of fossil fuels and
4 18uranium combined. The primary energy use in 2005 was “only” 487·10 J. As a
consequence, the complete need of energy could easily be provided by the sun, but
the problem is, how can it be harvested?
5DESERTEC is one concept of using wind and solar power in deserts in Europe,
the Middle East and North Africa. The idea is to use these areas with low population
but high amounts of solar radiation to produce electricity and to use this energy for
the global market. The power of the sun is harvested in two ways: as solar thermal
power and by photovoltaics. The first silicon-based solar cells were built by Gerald
Pearson, Calvin Fuller, and Daryl Chaplin in 1954. With an efficiency of 4.5% – 6%
the costs were