The (Non-)Local Density of States of Electronic Excitations in Organic Semiconductors (eBook)

Supervisor’s Foreword 6
Abstract 8
Parts of this thesis have been published in the following articles:Some of the sections and chapters of this thesis are adaptations and/or extensions of the following publications and manuscripts: C. Poelking, D. Andrienko: Long-Range Embedding of Molecular Ions and Excitations in a Polarizable Molecular Environment. Journal of Chemical Theory and Computation 12 (9) 4516–4523 (2016)G. D’Avino, L. Muccioli, F. Castet, C. Poelking, D. Andrienko, Z. Soos, J. Cornil, D. Beljonne: Electrostatic Phenomena in Organic Semiconductors: Fundamentals and Applications. Journal of Physics: Condensed Matter 28 (43) 433002 (2016)M. Schwarze, W. Tress, B. Beyer, F. Gao, R. Scholz, C. Poelking, K. Ortstein, A. A. Guenther, D. Kasemann, D. Andrienko, K. Leo: Band-Structure Engineering in Organic Semiconductors. Science 352 (6292) 1446–1449 (2016)C. Poelking and D. Andrienko: Design Rules for Organic Donor-Acceptor Heterojunctions: Pathway for Charge Splitting and Detrapping. Journal of the American Chemical Society 137(19) 6320–6326 (2015)P. Gemünden, C. Poelking, K. Kremer, K. Daoulas and D. Andrienko: Effect of Mesoscale Ordering on the Density of States in Polymeric Semiconductors. Macromolecular Rapid Communications 36(11) 1047–1053 (2015)C. Poelking, M. Tietze, C. Elschner, S. Olthof, D. Hertel, B. Baumeier, F. Würthner, K. Meerholz, K. Leo and D. Andrienko: Impact of Mesoscale Order on Open-Circuit Voltage in Organic Solar Cells. Nature Materials 14(4) 434–439 (2014)C. Poelking, K. Daoulas, A. Troisi and D. Andrienko: Morphology and Charge Transport in P3HT: A Theorist’s Perspective. Advances in Polymer Science 265 139–180 (2014)Previous work by the author of this thesis in the field of organic electronics and photovoltaics is published in the following journal articles: C. Poelking and D. Andrienko: Effect of Paracrystallinity, Polymorphism and Regioregularity on Charge Transport in Poly(3-Hexyl-Thiophene) Nanofibers. Macromolecules 46 (22) 8941–8956 (2013)P. Gemünden, C. Poelking, K. Kremer, D. Andrienko and K. Daoulas: Nematic Ordering, Conjugation and Density of States of Soluble Polymeric Semiconductors. Macromolecules 46 (14) 5762–5774 (2013)C. Poelking, E. Cho, A. Malafeev, V. Ivanov, K. Kremer, C. Risko, J.-L. Brédas and D. Andrienko: Characterization of Charge-Carrier Transport in Semicrystalline Polymers: Electronic Couplings, Site Energies, and Charge-Carrier Dynamics in Poly(bithiophene-alt-thienothiophene) [PBTTT] Journal of Physical Chemistry C 117 (4) 1633–1640 (2013)B. Baumeier, O. Stenzel, C. Poelking, D. Andrienko and V. Schmidt: Stochastic Modeling of Molecular Charge-Transport Networks. Physical Review B 86 184202 (2012)R. Lovrincic, J. Trollmann, C. Poelking, J. Brill, J. Schöneboom, C. Lennartz and A. Pucci: Orientation of Non-Planar Molecules in Polycrystalline Layers from Infrared Spectra: Core-chlorinated Naphthalene Tetracarboxylic Diimides. Journal of Physical Chemistry C 116 (9) 5757–5763 (2012)A. Ojala, A. Petersen, A. Fuchs, R. Lovrincic, C. Poelking, J. Trollmann, A. Pucci, C. Lennartz, H. Reichelt, P. Erk and F. Würthner: Merocyanine/C60 Planar Heterojunction Solar Cells: Effect of Dye Orientation on Exciton Dissociation and Solar Cell Performance. Advanced Functional Materials 22(1) 86–96 (2011)A. Chatten, D. Farrell, R. Bose, A. Dixon, C. Poelking, K. Godel, M. Mazzer and K. Barnham: Luminescent and Geometric Concentrators for Building Integrated Photovoltaics. Proceedings of the 37th IEEE Photovoltaic Specialists Conference PVSC 852–857 (2011) 9
Acknowledgements 11
Contents 12
1 Organic Electronics in a Nutshell 14
1.1 Materials 14
1.2 Devices 17
1.3 Challenges 20
References 22
2 Particle-Based Models of Organic Semiconductors 25
2.1 The Bottom-Up Simulation Workflow 25
2.2 Molecular Landscapes 27
2.2.1 Density Functional Theory 28
2.2.2 Molecular Dynamics 31
2.2.3 Atomistic Models 34
2.2.4 Coarse-Grained Models 37
2.2.5 Lattice Models 39
2.3 Charge Transport Networks 41
2.3.1 Charge Transfer Reactions 41
2.3.2 Graph Generation and Parametrization 44
2.4 Charge-Carrier Dynamics and Mobility 48
References 49
3 Long-Range Polarized Embedding of Electronic Excitations 52
3.1 The Mesoscopic Interaction Range 52
3.2 The Molecular Field and Field Response 55
3.2.1 Distributed Multipoles 56
3.2.2 Distributed Polarizabilities 58
3.3 Long-Range Polarized Embedding 61
3.3.1 Polarization Energy and Work 61
3.3.2 Aperiodic-Periodic Decomposition 63
3.3.3 Shape Terms 66
3.4 Interaction Kernels 68
3.4.1 Anisotropic Kernels 68
3.4.2 Isotropic Kernels 69
3.4.3 Thole Damping Kernels 69
3.4.4 Field Calculation 70
3.5 Computational Procedure for Site-Energy Calculations 71
3.6 Summary: Long-Range Polarized Embedding 74
References 75
4 Charge Carriers at Organic--Organic Interfaces 77
4.1 The Acceptor-Donor-Acceptor Puzzle 77
4.1.1 Level Profiles Across C60/D5M Interfaces 80
4.1.2 Experimental Validation 82
4.2 Orientation Effects and Film Patterning 83
4.2.1 Orientation Effects in Lattice Multilayers 84
4.2.2 Level Profiles in Patterned Thin Films 85
4.3 Charge Carriers at Donor-Acceptor Heterojunctions 88
4.3.1 Interplay of Molecular Architecture, Packing and Orientation 89
4.3.2 The Charge-Density-Dependent Open-Circuit Voltage 94
4.4 Charge Carriers at Grain Boundaries 96
4.5 Summary: Interface Energetics 99
References 100
5 Charge Carriers in Disordered Bulk Mesophases 103
5.1 Charge Carriers in Amorphous Dipolar Semiconductors 103
5.2 Charge Carriers in Polymeric Semiconductors 106
5.2.1 Partially Ordered Mesophases of Poly(3-Hexylthiophene) 106
5.2.2 Formation of Low-Energy States and Correlations 108
5.3 Summary: Mesophase Energetics 112
References 113
6 Charge Transfer States at Donor--Acceptor Heterojunctions 115
6.1 Pathway for Charge Splitting and Detrapping 115
6.1.1 Dielectric Solvation of Electron-Hole Pairs 117
6.1.2 The Role of Interfacial Defects 120
6.1.3 Charge Push-Out Forces at Rough Interfaces 122
6.2 Interface Polarity Versus Photovoltaic Gap 126
6.3 Charge Transfer Energetics and Open-Circuit Voltage 128
6.4 Summary: Charge Transfer Energetics 133
References 133
7 Conclusions and Outlook 136
References 141