Inhalt

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   Contents
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   1 Introduction – What it's all about and why
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   I Light-sensitive functional organic materials
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  2 Organic molecules
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   2.1 Formation of organic molecules and bonding
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   2.2 Optical excitation and relaxation of organic molecules
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  3 Energy and charge transport
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   3.1 Energy levels, ionization potential and electron affinity
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  3.2 Energy transfer
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   3.2.1 Förster resonant energy transfer
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   3.2.2 Dexter transfer
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   3.3 Charge separation
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   3.4 Charge transport processes
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  4 Common representative molecules
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   4.1 Donors
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   4.2 Acceptors
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   II Photorefractive polymer composites
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  5 Fundamentals of photorefractive properties in organic media
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   5.1 Photoconductivity
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  5.2 Electro-optic effect
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   5.2.1 Short introduction into nonlinear optics
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   5.2.2 Field-dependent refractive index change
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   5.2.3 Pockels effect
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   5.2.4 Kerr effect
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   5.2.5 Electro-optics in organic photorefractive materials
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   5.3 Photorefractive effect
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  5.4 Composition and sample layout
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   5.4.1 5CB
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  5.4.2 Fabrication of photorefractive samples
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   5.4.2.1 Electrode patterning and sample layout
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   5.4.2.2 Synthesis of photorefractive compositions
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   5.4.2.3 Assembly of the samples and melt-pressing
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  6 Photophysical characterization
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   6.1 UV/Vis spectroscopy
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  6.2 Photocurrent spectroscopy
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   6.2.1 Spectroscopy technique
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   6.2.2 Influence of different components on photocurrent
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   6.2.3 Transient development of dark conductivity and internal photocurrent efficiency
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   6.3 Two-beam coupling
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   6.3.1 Setup and fundamentals
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   6.3.2 Two-beam coupling performance of the realized compositions
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   6.3.3 History dependence
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   7 Resume and outlook on the realized organic PR media
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   III Bulk-heterojunction solar cells
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  8 Concepts of organic solar cell design and fabrication
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   8.1 Bilayer heterojunction
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   8.2 Bulk heterojunction
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   8.3 Fabrication of bulk heterojunction solar cells
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   8.3.1 Spin coating
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   Static dispense
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   Dynamic dispense
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   8.3.2 UV/ozone cleaning
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   8.3.3 Thermal metal evaporation
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   8.3.4 ITO electrode preparation
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   8.3.5 PEDOT:PSS layer deposition
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   8.3.6 Active layer deposition
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   8.3.7 Application of the aluminium back electrode
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   9 Characterization of organic solar cells
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  9.1 Structure analysis of polymer chains of P3HT
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   9.1.1 Preparation of thin films and solution containing good and bad solvent
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   9.1.2 Interpretation of the absorption spectra
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   9.2 Absorption spectroscopy and numerical modeling of P3HT:diPBI solar cells
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  10 Perylene derivative acceptors and applied donors
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  10.1 Material properties
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   10.1.1 PBI
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   10.1.2 Triply-linked diPBI
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   10.1.3 Singly-linked diPBI
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   10.1.4 PPDI
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   10.1.5 PBDTTT-C-T
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   10.1.6 PEDOT:PSS
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   10.1.7 Energy levels and absorption spectra
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  10.2 Solar cell prototypes and and their performance
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   10.2.1 Reference compostion: P3HT:PCBM
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   10.2.2 Stability considerations: Degradation of P3HT:PCBM cells
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   10.2.3 Monomeric perylene bisimide as acceptor
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   10.2.4 Triply-linked diPBI as acceptor
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   10.2.5 Imide-linked PPDI and PBDTTT-C-T
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   10.2.6 Singly-linked diPBI as acceptor and PBDTTT-C-T as donor materials
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   10.3 Differences between theoretical open-circuit voltage and obtained data
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   11 Resume on organic solar cell processing under ambient conditions
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   IV Photopatterning of azopolymers and light-propagation simulations
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   12 Azo compounds and cis-trans isomerization
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   13 Photomigration and surface relief gratings
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  13.1 Proposed mechanisms of light-induced mass transfer
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   13.1.1 Model 1: Optical-field gradient force model
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   13.1.2 Model 2: Mean-field model
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   13.1.3 Model 3: Pressure gradient force model
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   13.1.4 Model 4: Asymmetric diffusion model
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   13.1.5 Model 5: Photoinduced molecular diffusion model
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   13.1.6 Model 6: Thermal models
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   13.2 Conclusion of the proposed models
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  14 Fabrication of surface relief gratings
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   14.1 Two-beam interference setup
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  14.2 Phase-only spatial light modulator-based setup
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   14.2.1 Light patterning via phase-only spatial light modulation
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   14.3 Azopolymer film preparation
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   15 Realized patterns via two-beam interference
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   15.1 Maximization of height modulation
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  16 Realization of complex 2D patterns – between disorder and order
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   16.1 Nondiffracting beams: a short introduction
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   16.2 Bessel patterns – circular symmetry
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   16.3 Penrose patterns – quasiperiodic and nondiffracting
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   16.4 Cobblestone pattern – continuous frequency spectrum
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   16.5 Vogel spiral patterns – mimicking nature
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   17 Molding of SRGs into PDMS
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  18 Modeling of light propagation through patterned surfaces
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   18.1 FDTD technique
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   18.2 Simulation parameters and the PDMS-glass model
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   18.3 Visualization of redistributed light
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   19 Resume on SRG generation and light propagation
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   20 Outcome and outlook
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   Bibliography
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    Acronyms
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    List of Symbols
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    Glossary
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   Appendix
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  A Additional information and parameters
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   A.1 Conversion factors of the polarizability
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   A.2 Molecular weights of employed compounds
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   A.3 Solvent data
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   A.4 Good and bad solvent data
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   A.5 Maximum amplitudes obtained from simulated cross sections
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   Publications
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   Deutschsprachige Zusammenfassung
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   Lebenslauf (Curriculum Vitae)