University of Groningen

Large Scale Modelling of Photo-Excitation Processes in Materials with Application in OrganicPhotovoltaicsIzquierdo Morelos, Maria Antonia

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Large Scale Modelling of Photo-ExcitationProcesses in Materials with Application in Organic

Photovoltaics

María Antonia Izquierdo Morelos

Large Scale Modelling of Photo-Excitation Processes in Materials with Application inOrganic Photovoltaics

María Antonia Izquierdo Morelos

PhD thesisUniversity of GroningenThe Netherlands

Zernike Institute PhD thesis series 2019-16ISSN: 1570-1530ISBN: 978-94-034-1639-7 (printed version)ISBN: 978-94-034-1638-0 (electronic version)

The work presented in this thesis was performed in the Theoretical Chemistry groupof the Zernike Institute for Advanced Materials at the University of Groningen, TheNetherlands, in the Quantum Chemistry of the Excited State University of Valencia,Spain and in the Amsterdam-based company Software for Chemistry & Materials, TheNetherlands. This thesis is part of a European Joint Doctorate (EJD) in TheoreticalChemistry and Computational Modelling (TCCM), which was financed under the frame-work of the Innovative Training Networks (ITN) of the MARIE Skłodowska-CURIEActions (ITN-EJD-642294-TCCM).

08/07/16 14:35

Page 1 of 1https://www.scm.com/wp-content/themes/scm/images/logos/scm-logo.svg

Cover artwork: “Lightopia” by the Venezuelan artist Carlos Cruz DiezCover design: Ilse Modder, www.ilsemodder.nlPrinted by Gildeprint - Enschedec, 2019 María Antonia Izquierdo Morelos

Large Scale Modelling of Photo-ExcitationProcesses in Materials with Application in Organic

Photovoltaics

PhD thesis

to obtain the degree of PhD of theUniversity of Groningenon the authority of the

Rector Magnificus Prof. E. Sterkenand in accordance with

the decision by the College of Deans

and

to obtain the degree of PhD of theUniversity of Valenciaon the authority of the

Rector Magnificus Prof. M. V. Mestre Escriváand in accordance with

the decision by the College of Deans

Double PhD Degree

This thesis will be defended in public on

Friday 3 May 2019 at 14:30 hours

by

María Antonia Izquierdo Morelos

born on 20 August 1987in Barinas, Venezuela

Supervisors

Prof. R. BroerProf. A. Sánchez de Merás

Co-supervisor

Dr. D. Roca Sanjuán

Assessment Committee

Prof. L. J. A. KosterProf. E. Ortí GuillénProf. M. SwartProf. T. P. Straatsma

“Your future hasn’t been written yet. No one’s has. Your future iswhatever you make it. So make it a good one.”

Emmett "Doc" Brown

Table of Contents

Prologue 11Chapter 1: Fundamentals of Electronic and Optoelectronic Processes 13

1.1. Overview 131.2. Organic Photovoltaics 131.2.1. Operating Principle 131.2.2. Device Architectures 141.2.3. Efficiency 151.2.4. Materials for D:A BHJs 151.2.5. Challenges 18

1.3.Efficiency Losses in Optoelectronics: Radiationless Decay Mechanisms . 19References 22

Chapter 2: Objectives 272.1. General Objective 272.2. Specific Objectives 27

Chapter 3: Electronic Structure Methods 293.1. Overview 293.2. Hartree-Fock Theory and Electron Correlation Methods 303.2.1.Hartree-Fock Theory 303.2.2. Multi-Determinant Methods and Electron Correlation 33

3.3. Density Functional Theory 373.3.1. Kohn-Sham Equations 38

3.4. Time-Dependent Density Functional Theory 393.4.1. Linear Response of the Density Matrix 40

3.5. Embedding Models 413.5.1. Polarizable Continuum Model 413.5.2. Discrete Reaction Field Within the DFT Framework 42

3.6. Conical Intersections: Beyond the BO Approximation 42References 45

Chapter 4: Extended Implementation of the Discrete Reaction Field Method 49in the Amsterdam Density Functional Modelling Suite

4.1. Overview 494.2. Atomic Charges and Atomic Polarizabilities 50

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CHAPTER 0. TABLE OF CONTENTS

4.3. Test on Atomic Charges and Atomic Polarizabilities 504.4. Improved DRF Inputs for ADF 534.4.1. DRF Inputs from the GUI 534.4.2. DRF Inputs Coupled to PLAMS 53

References 55Chapter 5: Calibration of Exchange-Correlation Functionals for Charge Trans- 57fer States 57

5.1. Overview 575.2. Charge Transfer Energy of a D/A Model System 575.3. Conclusions 59References 62

Chapter 6: Theoretical Study of the Charge Transfer Exciton Binding Energy 63in Semiconductor Materials for Polymer:Fullerene Based Bulk Heterorojuncti-on Solar Cells

Abstract 636.1. Introduction 646.2. Methods 686.3. Results and Discussion 706.3.1. Absorption Properties of Photovoltaic Materials 706.3.2. Charge Transfer Energy and Exciton Binding Energy in BHJs 73

6.4. Conclusions 79References 81

Chapter 7: Ab initio Quantum Chemistry Study of Luminescence in ⇡-Conju- 85gated Compounds with Applications to Optoelectronic DevicesAbstract 85

7.1. Introduction 867.2. Methods 907.3. Results and Discussion 917.3.1. Ethene, Styrene and Stilbene 917.3. 2. DSB,↵-DMDCS, �-DMDCS, ↵-TFDCS and �-TFDCS 96

7.4. Conclusions 103References 105

Chapter 8: Outlook and Perspective 1098.1. Overview 1098.2. Implementation of QM/DRF Energy Gradients in ADF 1098.3. Electronic Couplings in D:A OPVs via NOCI 110References 112

Chapter 9: Conclusions 113Appendix A 115

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CHAPTER 0. TABLE OF CONTENTS

Appendix B 121Summary 133Samenvatting 137Resumen 141List of Acronyms 151Curriculum Vitae 155Acknowledgments 159

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CHAPTER 0. TABLE OF CONTENTS

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Prologue

Organic photovoltaics represent a highly attractive choice of power generation in termsof cost and flexibility. However, the low efficiencies attained up to now limit theirsignificant application. Such limitation has certainly stimulated fundamental researchfocused on materials design and device architectures. This dissertation, Large ScaleModelling of Photo-Excitation Processes in Materials with Application in Or-ganic Photovoltaics, investigates -using first principles theory and modelling- moreefficient optoelectronic materials. New materials with promising applications in thefield are proposed. Special attention is given to electron transfer processes in very largesystems and to the prediction of non-radiative mechanisms that contribute to efficiencylosses.

This thesis intends to be reader friendly, thus, it is structured in such a way thateach Chapter is self-contained (although at the end of this manuscript a list of acronymsis presented). Chapter 1 provides the background for studying the photovoltaic andoptoelectronic processes in organic photovoltaics. The state-of-the-art and the currentchallenges in the field are also described. Chapter 2 outlines the general objectiveand then it goes through the specific goals. Chapter 3 introduces the theoretical andcomputational methodologies used along this thesis. Methodologies are only brieflyexplained. A list of references is provided in case more details are required. Chapter 4reports the software development contribution of this work. The extended implemen-tation of a polarizable force field, which is part of the Amsterdam Density Functionalmodeling suite released in 2017, is described. Chapter 5 describes a calibration ofexchange-correlation functionals for density functional theory-based methods as thebasis for the next Chapter. Chapter 6 studies the charge transfer exciton binding ener-gies in organic semiconductor materials for polymer:fullerene bulk heterojunction solarcells, and consists of a scientific paper published in the Journal of Physical Chem-istry A. Chapter 7 explores the potential energy surfaces of optoelectronic materials,and it is part of a scientific paper in preparation at the time of the thesis submission.Chapter 8 suggests further research lines connected to this project. Chapter 9 closeswith the main achievements and general conclusions. For completeness, supplementaryappendices and transferable academic achievements are presented.

This thesis is part of a European Joint Doctorate (EJD) in Theoretical Chem-istry and Computational Modelling (TCCM) of the University of Groningen (UG) and

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CHAPTER 0. PROLOGUE

the University of Valencia (UV), in collaboration with the Software for Chemistry &Materials (SCM) company based in Amsterdam, financed by the Innovative TrainingNetworks (ITN) of the MARIE Skłodowska-CURIE Actions (ITN-EJD-642294-TCCM).

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