Organic Photovoltaics: Materials, Device Physics, and Manufacturing Technologies -- Contents -- List of Contributors -- Part One: Materials for Thin Film Organic Photovoltaics -- 1 Overview of Polymer and Copolymer Materials for Organic Photovoltaics -- 1.1 Introduction -- 1.2 Early Efforts -- 1.3 Toward Devices with 5% Efficiencies -- 1.4 Novel Thiophene-Containing Polymers -- 1.5 Fluorene-Containing Molecules -- 1.6 Carbazole-Based Copolymers -- 1.7 New Heterocyclic Polymers -- 1.8 Polymers Based on Other Types of Building Blocks -- 1.9 Conclusions -- References -- 2 Thiophene-Based High-Performance Donor Polymers for Organic Solar Cells -- 2.1 Introduction -- 2.2 Bandgap Engineering -- 2.3 Charge Generation in Bulk Heterojunction Organic Solar Cells -- 2.4 Polyalkylthiophenes -- 2.4.1 Synthesis -- 2.4.2 Optical and Solid-State Properties -- 2.5 Polyalkylthiophene/PCBM Blends -- 2.6 Polythiophene Copolymers -- 2.7 Side Chain Functionalized P3AT Derivatives -- 2.8 Third-Generation Polythiophenes -- 2.9 Thiophene-Based Push-Pull Copolymers -- 2.10 Benzo[1,2-b:4,5-b0]dithiophene-Based Polymers -- 2.11 Cyclopenta[2,1-b:3,4-b0]dithiophene-Based Polymers -- 2.12 Indacenodithiophene-Based Polymers -- 2.13 Conclusion and Outlook -- References -- 3 Molecular Design of Conjugated Polymers for High-Efficiency Solar Cells -- 3.1 Introduction -- 3.2 Structural Features of Conjugated Polymers -- 3.3 "D-A" Approach -- 3.3.1 Rational Design of Conjugated Backbones: "Weak Donor-Strong Acceptor" Copolymer -- 3.3.1.1 "Weak Donor" Moieties to Improve VOC -- 3.3.1.2 Balancing VOC and JSC: Interplay of Bandgap and Energy Levels -- 3.3.1.3 From BT to 4DTBT: Why is a "Soluble Acceptor" Better? -- 3.3.1.4 "Strong Acceptor" Moieties to Increase JSC -- 3.3.2 Side Chains Are NOT Trivial -- 3.3.2.1 Chain Positions -- 3.3.2.2 Shape and Size.

3.3.3 Substituents Do Matter: The Curious Case of Fluorine -- 3.4 Quinoid Approach -- 3.5 Summary and Outlook -- References -- 4 Solution-Processed Molecular Bulk Heterojunction Solar Cells -- 4.1 Introduction -- 4.2 Monochromophoric Molecules -- 4.2.1 Conjugated Macrocycles and Polycycles -- 4.2.2 Acenes and Heteroacenes -- 4.2.3 Oligothiophenes -- 4.3 Multichromophoric Molecules -- 4.3.1 Colorant Chromophore-Containing Derivatives -- 4.3.1.1 Diketopyrrolopyrrole and Isoindigo Derivatives -- 4.3.1.2 Squaraine Derivatives -- 4.3.1.3 Merocyanine and Borondipyrromethene Derivatives -- 4.3.2 Oligothiophene Derivatives -- 4.3.3 Benzothiadiazole Analogue Derivatives -- 4.3.4 Triphenylamine Derivatives -- 4.4 Summary and Future Directions -- References -- 5 Vacuum-Processed Donor Materials for Organic Photovoltaics -- 5.1 Introduction -- 5.1.1 Basic Characterization of Organic Solar Cells -- 5.2 Planar and Bulk Heterojunction Solar Cells -- 5.3 Summary and Future Prospects -- Acknowledgments -- References -- 6 Polymer-Nanocrystal Hybrid Solar Cells -- 6.1 Introduction -- 6.2 Semiconductor Nanocrystals -- 6.3 Working Principles and Device Structure -- 6.3.1 Donor and Acceptor Materials -- 6.4 Evolution of Polymer-NC Hybrid Solar Cells -- 6.5 Recent Approaches for Overcoming Current Limitations -- 6.5.1 In Situ Synthesis of NCs in the Polymer Film -- 6.5.2 Nanostructured Polymer-Based Assemblies in Solution -- 6.5.3 Lower Bandgap NC Acceptors -- 6.6 Novel Concepts and Perspectives -- 6.6.1 Ternary NC Systems: Energy Level and Bandgap Tuning -- 6.6.2 NC Ligand Design -- 6.6.3 Functionalized Polymers -- 6.6.4 Inorganic Framework for Interdigitated D-A Layers -- 6.6.4.1 Porous Alumina Template-Assisted Approach -- 6.6.4.2 Nanostructured Inorganic Semiconductors as Acceptor Material -- 6.6.5 Nanostructured Polymer.

6.6.6 Carbon-Based Acceptors and Nanocomposites -- 6.6.7 Less Toxic NC Acceptor Materials -- 6.7 Summary and Outlook -- Acknowledgments -- References -- 7 Fullerene-Based Acceptor Materials -- 7.1 Introduction and Overview -- 7.2 Fullerenes as n-Type Semiconductors -- 7.2.1 Electron-Accepting and Transporting Properties -- 7.2.2 Other Electronic Properties -- 7.3 Fullerene Derivatives -- 7.3.1 [60]PCBM -- 7.3.2 [60]PCBM Analogues -- 7.3.3 Substituents on the Phenyl Moiety of PCBM -- 7.3.3.1 Alkoxy Groups -- 7.3.3.2 Fluorination -- 7.3.3.3 Deuterium Labeling -- 7.3.4 Other C60 Derivatives in OPVs -- 7.4 Derivatives of C70 and C84 -- 7.4.1 Derivatives of C70 -- 7.4.2 Derivatives of C84 -- 7.5 Fullerene Bisadducts -- 7.6 Endohedral Compounds -- 7.7 Commercialization of Fullerene Derivatives -- References -- 8 Polymeric Acceptor Semiconductors for Organic Solar Cells -- 8.1 Introduction -- 8.2 Basics Principles and Operation for Organic Solar Cells -- 8.3 Polymeric Acceptor Semiconductors -- 8.3.1 Cyanated Polyphenylenevinylenes -- 8.3.2 Perylene- and Naphthalenediimide-Based Polymers -- 8.3.3 Benzothiadiazole-Based and Other Electron-Poor Polymers -- 8.4 Conclusions and Perspective -- References -- 9 Water/Alcohol-Soluble Conjugated Polymer-Based Interlayers for Polymer Solar Cells -- 9.1 Introduction -- 9.2 The Development of Water/Alcohol-Soluble Conjugated Polymers as Interlayer Materials -- 9.3 Interface Engineering for Polymer Solar Cells -- 9.3.1 Interface Modification for Metal Electrodes -- 9.3.2 Interface Modification for Metal Oxide Electrodes -- 9.3.3 Interface Modification for Graphene and Carbon Nanotube Electrodes -- 9.4 Discussion of the Working Mechanism -- 9.5 Summary -- References -- 10 Metal Oxide Interlayers for Polymer Solar Cells -- 10.1 Introduction -- 10.2 Conventional Structure -- 10.2.1 Hole-Selective Layer: Replacing PEDOT:PSS.

10.2.1.1 Nickel Oxide -- 10.2.1.2 Vanadium, Molybdenum, and Tungsten Oxides -- 10.2.2 Electron-Selective Layer -- 10.2.2.1 Titanium and Zinc Oxides -- 10.3 Inverted Structure -- 10.3.1 Electron-Selective Layer: Reducing the Effects of Cathode Oxidation -- 10.3.1.1 Titanium, Zinc, and Cesium Oxides -- 10.3.1.2 Modification via Molecular Self-Assembly -- 10.4 Tandem Structure -- 10.5 Additional Oxides (Cr2O3, CuOx, PbO) -- 10.6 Conclusions -- References -- Part Two: Device Physics of Thin Film Organic Photovoltaics -- 11 Bimolecular and Trap-Assisted Recombination in Organic Bulk Heterojunction Solar Cells -- 11.1 Introduction -- 11.2 Recombination at Open Circuit -- 11.3 Trap-Assisted Recombination at Open Circuit -- 11.4 Investigation of the Nature Recombination by Electroluminescence Measurements -- 11.5 Bimolecular Recombination Strength in Organic BHJ Solar Cells -- 11.6 Bimolecular Recombination Losses Under Short-Circuit Conditions -- 11.7 Effect of Bimolecular Recombination on Fill Factor and Efficiency -- 11.8 Conclusions -- References -- 12 Organic Photovoltaic Morphology -- 12.1 Introduction -- 12.2 Order in Bulk Heterojunctions -- 12.2.1 Optical Measurements of Order -- 12.2.2 X-Ray Measurement of Crystallinity -- 12.3 Nanoscale Morphology in Bulk Heterojunctions -- 12.3.1 Electron Microscopy -- 12.3.2 Small-Angle Scattering Measurements -- 12.4 Phases in a Bulk Heterojunction -- 12.5 Structure of the Interface between Phases -- 12.5.1 Inferences from Bulk Measurements -- 12.5.2 Surface-Sensitive Measurements -- 12.5.3 Measuring Buried Bilayer Interfaces -- 12.5.4 Measuring Buried Bulk Interfaces -- 12.6 In Situ Measurements of Morphology Development -- 12.6.1 In Situ X-Ray Measurements -- 12.6.2 In Situ Microscopy -- 12.6.3 In Situ Optical and Vibrational Spectroscopies -- 12.6.4 In Operando Measurements.

12.6.5 The Future of In Situ Measurement -- References -- 13 Intercalation in Polymer:Fullerene Blends -- 13.1 Introduction -- 13.2 Methods for Detecting Molecular Mixing -- 13.2.1 X-Ray Diffraction -- 13.2.2 Photoluminescence Measurements -- 13.2.3 Diffusion Measurements -- 13.2.4 Transmission Electron Microscopy Techniques -- 13.2.5 Small-Angle Scattering Techniques -- 13.3 Factors Affecting Molecular Mixing -- 13.3.1 Fullerene Size -- 13.3.2 Side-Chain Attachment Distance -- 13.3.3 Side-Chain Linearity -- 13.3.4 Thermal Treatments -- 13.4 The Effect of Molecular Mixing on Electronic Properties and Solar Cells -- 13.4.1 Exciton Harvesting -- 13.4.2 Geminate Pair Separation, Charge Extraction, and Optimal Blend Ratio -- 13.4.3 Additional Device Implications -- 13.5 Conclusions -- References -- 14 Organic Tandem Solar Cells -- 14.1 Introduction and Working Principle -- 14.2 Measurement Techniques -- 14.3 Efficient Intermediate Charge Carrier Recombination -- 14.4 Light Management -- 14.5 Choice of Materials -- 14.6 Parallel Tandem Architectures -- 14.7 New Tandem Solar Cell Concepts -- 14.8 Conclusions -- Acknowledgments -- References -- 15 Solid-State Dye-Sensitized Solar Cells -- 15.1 Introduction -- 15.2 Working Principles of Solid-State Dye-Sensitized Solar Cells -- 15.2.1 Solar Cell Geometries -- 15.2.2 Light Absorption and Charge Separation -- 15.2.3 Charge Transport -- 15.3 Loss Mechanisms in Solid-State Dye-Sensitized Solar Cells -- 15.4 Solid-State Dye-Sensitized Solar Cells with Spiro-OMeTAD as Hole Conductor -- 15.5 Hybrid Solar Cells with Absorbing Hole Conductors -- 15.6 Ordered Nanostructures for Solid-State Dye-Sensitized Solar Cells -- 15.6.1 TiO2 Nanowires -- 15.6.2 TiO2 Nanotubes -- 15.7 Summary and Outlook -- References -- Part Three: Technology for Thin Film Organic PV.

16 Reel-to-Reel Processing of Highly Conductive Metal Oxides.