Organic Solar Cells

Liming Ding, PhD, is Full Professor at the National Center for Nanoscience and Technology. His research is focused on optoelectronic materials and devices, organic solar cells, perovskite solar cells, and photodetectors. He received his doctorate from the University of Science and Technology of China.

• Preface xv1 Conjugated Polymer Donors for Organic Solar Cells 1Xiaopeng Xu, Xiyue Yuan, Qunping Fan, Chunhui Duan, Maojie Zhang, and Qiang Peng1.1 Introduction 11.2 LBG Polymers 31.2.1 LBG Polymers Based on Benzothiadiazole (BT) 31.2.2 LBG Polymers Based on Isoindigo (IID) 81.2.3 LBG Polymers Based on Diketopyrrolopyrrole (DPP) 141.3 MBG Polymers 191.3.1 MBG Polymers Based on Benzothiadiazole (BT) 221.3.2 MBG Polymers Based on Quinoxaline (Qx) 311.3.3 MBG Polymers Based on Thienopyrrolodione (TPD) 351.3.4 MBG Polymers Based on Thieno[3,4-b]thiophene (TT) 401.4 WBG Polymers 461.4.1 WBG Polymers Based on Polythiophene (PT) Derivatives 461.4.2 WBG Polymers Based on Benzodithiophene-alt-Thiophene Derivatives 491.4.3 WBG Polymers Based on Benzothiadiazole (BT) Derivatives 501.4.4 WBG Polymers Based on Benzotriazole (BTA) Derivatives 531.4.5 WBG Polymers Based on Thiazole, Pyrazine, and Their Derivatives Containing N-Heterocycles 561.4.6 WBG Polymers Based on Benzodithiophene-4,8-dione (BDD) Derivatives 621.4.7 Other WBG Polymers 651.5 Summary and Outlook 69References 692 p-Type Molecular Photovoltaic Materials 77Qihui Yue and Xiaozhang Zhu2.1 Introduction 772.2 p-Type Molecular Photovoltaic Materials Used in Vacuum-Deposited Solar Cells 782.2.1 Oligothiophene-Based Molecular Donors 792.2.2 D-A-A′ -Type Molecular Donors 802.2.3 Borondipyrromethenes-Based Molecular Donors 832.2.4 Other Molecular Donors 852.3 p-Type Molecular Photovoltaic Materials Used in Solution-Processed Solar Cells 882.3.1 A–D–A-Type Molecular Donors 892.3.1.1 Oligothiophene-Based A–D–A-Type Molecular Donors 892.3.1.2 Benzodithiophene-Based A–D–A-Type Molecular Donors 902.3.1.3 Dithienosilole-Based A–D–A-Type Molecular Donors 952.3.1.4 Dithienopyrrole-Based A–D–A-Type Molecular Donors 962.3.2 D1-A-D2-A-D1-Type Molecular Donors 962.3.2.1 Dithienosilole-Based D1-A-D2-A-D1-Type Molecular Donors 992.3.2.2 Benzodithiophene-Based D1-A-D2-A-D1-Type Molecular Donors 1012.3.2.3 Indacenodithiophene-Based D1-A-D2-A-D1-Type Molecular Donors 1032.3.3 Porphyrin-Based Molecular Donors 1052.3.4 Other Molecular Donors 1072.4 Current Progress on Small-Molecule Solar Cells with Nonfullerene Acceptors 1102.4.1 Binary Solar Cells 1112.4.2 Ternary Solar Cells 1122.5 Summary and Outlook 114References 1153 Fullerene Acceptors 121Zuo Xiao3.1 Introduction 1213.2 Fullerene Acceptors for Organic Solar Cells 1233.2.1 Pristine Fullerenes 1233.2.2 Fullerene Monoadducts 1263.2.2.1 [2+1] Addition Derivatives 1263.2.2.2 [2+2] Addition Derivatives 1293.2.2.3 [2+3] Addition Derivatives 1293.2.2.4 [2+4] Addition Derivatives 1303.2.2.5 1,4-Addition Derivatives 1303.2.3 Fullerene Bisadducts 1303.2.4 Fullerene Multiadducts 1353.2.5 Unconventional Fullerenes 1363.3 Summary 138References 1394 Non-fullerene Small-Molecule Acceptors for Organic Solar Cells 145Wei Gao, Jun Yuan, Zhenghui Luo, Jinru Cao, Weihua Tang, Yingping Zou, and Chuluo Yang4.1 Molecular Design Principles 1454.2 PDI-Based SMAs 1464.2.1 PDI Monomers 1464.2.2 PDI Dimers 1474.2.3 PDI Trimers 1504.2.4 PDI Tetramers 1534.3 A–D–A-Type SMAs 1604.3.1 Side Chains Optimization 1604.3.2 End Groups Engineering 1644.3.3 Core Units Engineering 1674.3.3.1 IDTT and Its Derivations 1674.3.3.2 Spacer Unit Effects 1764.3.3.3 Asymmetric Cores 1844.3.3.4 Non-fused Cores 1944.4 A–DA′ D–A–Type SMAs 2004.4.1 BTA-Based A–DA′ D–A SMAs 2014.4.2 BT-Based A–DA′ D–A SMAs 2044.4.3 BSe- and Qx-Based OSCs 209References 2105 Electron-Donating Ladder-Type Heteroacenes for Photovoltaic Applications: From Polymer Donor Materials to Small-Molecule Acceptor Materials 215Qisheng Tu, Yunlong Ma, and Qingdong Zheng5.1 Introduction 2155.2 D–A Copolymers Based on Ladder-Type Heteroacenes 2175.2.1 Pentacyclic and Hexacyclic Heteroacenes-Based D–A Copolymers 2175.2.2 Heptacene-Based D–A Copolymers 2195.2.3 D–A Copolymers Based on Heteroacenes with Nine or More Fused Rings 2225.3 A–D–A NFAs Based on Ladder-Type Heteroacenes 2235.3.1 A–D–A NFAs Based on Heteropentacenes and Heterohexacenes 2245.3.2 A–D–A NFAs Based on Heteroheptacenes 2265.3.2.1 NFAs Based on Heteroheptacenes with sp3-Hybridized Bridging Atoms 2265.3.2.2 NFAs Based on Heteroheptacenes Without sp3-Hybridized Bridging Atoms 2315.3.3 A–D–A NFAs Based on Heteroacenes with Eight or More Fused Rings 2335.3.4 Other NFAs 2355.4 Conclusions and Outlook 236References 2376 Chlorinated Organic Solar Cells 241Hui Chen, Mingrui Pu, and Feng He6.1 Introduction 2416.2 Chlorination Versus Fluorination: A Comprehensive Study 2426.2.1 Synthesis 2426.2.2 The Manipulation of Energy Level and Absorption 2446.2.3 The Steric Hindrance and Morphology 2456.2.4 The Synergistic Effect of Chlorination and Fluorination 2466.3 Recent Advances in Chlorinated Semiconductors 2496.3.1 Chlorination on the Donor Units of Polymer Donors 2496.3.1.1 Chlorination of the Donor Units in Backbone of Polymer Donors 2496.3.1.2 Chlorination of the Donor Units in Side Chain of Polymer Donors 2506.3.2 Chlorination on the Acceptor Units of Polymer Donors 2556.3.3 Chlorination of the π-Bridge of the Polymer Donors 2586.3.4 Chlorinated Small Molecular Donors 2606.3.5 Chlorinated Small Molecular Acceptors 2606.3.5.1 Photovoltaic Performance of Chlorinated Small Molecular Acceptors 2626.3.5.2 The Investigation of the Crystal Structure of Chlorinated Small Molecular Acceptors 2666.3.5.3 The Semitransparent Organic Solar Cells Based on Chlorinated Small Molecular Acceptors 2686.4 Conclusion and Outlook 269References 2707 Polymer–Polymer Solar Cells: Materials, Device, and Stability 275Jianyu Yuan, Huiliang Sun, Yingjian Yu, Wanli Ma, Xugang Guo, and Jun Liu7.1 Introduction 2757.2 The Device Structure and Basic Principles of All-PSCs 2777.3 Materials Design Toward Efficient All-PSCs 2787.3.1 Progress of N2200 and Its Derivative-Based All-PSCs 2787.3.1.1 Molecular Design Strategy for N2200 Derivatives 2797.3.1.2 Molecular Design Strategy for PDI Polymers 2837.3.1.3 Molecular Design Strategy for BTI Polymers 2837.3.1.4 BTI Polymers for High-Performance All-PSCs with Small Eloss 2877.3.2 Progress of Polymer Acceptors Containing B←N Unit 2897.3.2.1 Principle of B←N Unit 2897.3.2.2 Electron-Deficient Building Blocks Based on B←N Unit 2897.3.2.3 Optimizing ELUMO 2927.3.2.4 Tuning Absorption Spectra 2947.3.2.5 Enhancing Electron Mobility 2957.3.2.6 Optimizing Active Layer Morphology 2977.3.3 Progress of Polymer Acceptors Bearing Cyano Groups 2997.4 Device Performance and Stability of All-PSCs 3037.4.1 Morphology Optimization and Device Engineering 3037.4.2 The Enhanced Stability of All-PSCs 3077.4.2.1 Thermal Stability 3077.4.2.2 Ambient Stability 3087.4.2.3 Mechanical Stability 3087.4.2.4 Photostability 3097.5 Conclusion and Outlook 310References 3108 Organic Solar Cells with High Open-Circuit Voltage >1 V 313Ailing Tang, Yuze Lin, and Erjun Zhou8.1 Introduction 3138.2 n-Type Small-Molecule Acceptors 3158.2.1 Fullerene-Based SMAs 3158.2.2 Non-fullerene SMAs 3178.2.2.1 PDI-Based SMAs 3178.2.2.2 IC and Its Derivatives-Based A–D–A-Type SMAs 3198.2.2.3 A2-A1-D-A1-A2-Type SMAs with BT as A1 Units 3228.2.2.4 A2-A1-D-A1-A2-Type SMAs with BTA or Qx as A1 Units 3258.3 n-Type Polymers 3288.4 Conclusion and Outlook 330References 3319 Single-Component Organic Solar Cells 335Guitao Feng, Yiting Guo, and Weiwei Li9.1 Introduction 3359.2 Single-Component Conjugated Materials for SCOSCs 3369.2.1 Molecular Dyads 3369.2.1.1 Fullerene-Based “In-Chain” Molecular Dyads 3369.2.1.2 Fullerene-Based “Side-Chain” D–A Molecular Dyads 3399.2.1.3 PBI-Based Molecular Dyads 3419.2.2 Block Copolymers 3459.2.3 Double-Cable Conjugated Polymers 3509.3 Morphological Studies of the Photo-Active Layers in the SCOSCs 3619.3.1 Morphological Studies of the Molecular Dyads in SCOSCs 3629.3.2 Morphological Studies of the Block Copolymers in SCOSCs 3669.3.3 Morphological Studies of the Double-Cable Polymers in SCOSCs 3679.4 Perspective and Challenges of SCOSCs 375References 37710 Tandem Organic Solar Cells: Recent Progress and Challenge 381Lingxian Meng, Xiangjian Wan, and Yongsheng Chen10.1 Introduction 38110.2 Active Layer Materials in Tandem OSCs 38310.2.1 Tandem OSCs Based on Fullerene Acceptors 38410.2.2 Tandem OSCs Based on Non-fullerene Acceptors 39310.3 Interconnecting Layer Materials 39710.4 The Semi-Empirical Analysis of Tandem OSCs 39810.5 Conclusion and Outlook 400Acknowledgments 401References 40111 Large-Area Flexible Organic Solar Cells 405Shaorong Huang, Yufei Wang, Lintao Hou, and Lie Chen11.1 Introduction 40511.2 Material Requirements for Large-Area Flexible Organic Solar Cells 40611.2.1 Fullerene-Based Binary System 40611.2.2 Non-fullerene-Based Binary System 41011.2.3 Ternary System 41311.2.4 All-Polymer-Based System 41511.2.5 Design Strategies of the Materials for Large-Area Devices 41711.3 Flexible Electrodes and Substrates 41711.3.1 Flexible Substrates 41811.3.2 Flexible Transparent Electrode Designs 41911.3.2.1 Conducting Polymers 41911.3.2.2 Carbon Nanotubes 42311.3.2.3 Graphene 42611.3.2.4 Metallic Nanowires 42911.3.2.5 Hybrid Films 43211.4 Large-Area Flexible Device Fabrication 43411.4.1 Coating and Printing Methods 43511.4.1.1 Blade Coating 43611.4.1.2 Slot-Die Coating 43811.4.1.3 Inkjet Printing 44011.4.1.4 Spray Coating 44111.4.1.5 Screen Printing, Relief Printing, and Gravure Printing 44211.4.2 R2R Methodology 44311.5 Efficiency Loss in Large-Area Devices and Modules 44511.5.1 Electrical Loss 44611.5.2 Geometric Loss 44711.5.3 Optical Loss 44811.5.4 Additional Loss 44811.5.5 Modular Designs 44811.6 Conclusion and Outlook 449References 44912 Organic Photovoltaics for Indoor Applications 455Zhan′ ao Tan, Yinglong Bai, and Shan Jiang12.1 Introduction 45512.2 The Characteristics of Indoor Lighting Sources 45812.3 Testing System and Parameters for Indoor OPVs 46012.4 Research Progresses 46112.4.1 Fullerene-Based OPVs for Indoor Application 46212.4.2 Non-fullerene-Based OPVs for Indoor Application 47212.4.3 Multiple Blend OPVs for Indoor Application 47412.4.4 Interface Engineering of OPVs for Indoor Application 47612.4.5 Thick Film OPVs for Indoor Application 47912.4.6 Large-Area OPVs for Indoor Application 48012.5 Summary and Prospective 483References 48413 Interfacial Design for Efficient Organic Solar Cells 487Yao Liu, Menglan Lv, and Shengjian Liu13.1 Introduction 48713.2 The Mechanism and Effect of Interfacial Design 48813.2.1 The Role of Electrode Work-Function Difference 48813.2.2 The Interaction Between Metal Electrode and Interlayers 49013.2.3 Doping Effect on Energy Level Alignment 49213.2.4 Interface on BHJ Morphology and Device Stability 49413.2.5 Interfacial Morphology Characterizations 49513.3 Anode Interlayer Materials 49613.3.1 PEDOT:PSS 49613.3.2 Conjugated Polyelectrolytes 50113.3.3 Cross-Linkable Polymers 50213.3.4 Graphene Oxides (GOs) 50413.3.5 Metal Oxides (MOs) 50513.4 Cathode Interlayer Materials 50613.4.1 Organic Small Molecules 50613.4.2 Polymer Cathode Interlayer Materials 51013.4.3 Graphene Derivatives and Other Emerging Alternatives 51213.5 Conclusion and Outlook 513References 51414 Morphological Characterization and Manipulation of Organic Solar Cells 519Wei Li, Long Ye, and Tao Wang14.1 Introduction 51914.2 Morphological Characterization of Organic Solar Cells 52114.2.1 Microscopic Methods 52114.2.2 Scattering Methods 52614.2.3 Depth Profile 53414.3 Morphological Manipulation of Organic Solar Cells 53814.3.1 Thermal Annealing 53814.3.2 Solvent Vapor Annealing 54014.3.3 Solvent 54214.3.4 Solvent Additive 54414.3.5 Solid Additive 54714.3.6 Substrate Effect 54914.4 Conclusion 551References 55215 Operational Stability and Built-in Potential in Organic Solar Cells 555Weixia Lan, Bo Wu, and Furong Zhu15.1 Introduction 55515.2 Bimolecular Recombination in Organic Solar Cells 55715.2.1 Effect of Metal Oxide Interlayer on Cell Performance 55715.2.2 Charge Recombination Processes in Organic Solar Cells 56015.2.3 Bias-Dependent Charge Collection 56415.3 Metal/Organic Interfacial Exciton Dissociation in Organic Solar Cells 56515.3.1 Charge Collection in Regular Configuration Organic Solar Cells 56615.3.2 Charge Collection in Inverted Organic Solar Cells 56915.4 Improvement of Charge Collection and Performance Reproducibility 57115.4.1 Effect of Metal Oxide Interlayer on Cell Performance 57115.4.2 Suppression of ZnO Sub-Gap States 57415.5 Effect of Built-in Potential on Stability of Organic Solar Cells 57915.5.1 Interlayer Modification 58015.5.2 Built-in Potential in Organic Solar Cells 58215.5.3 Stability of Organic Solar Cells 58415.6 Summary 587Acknowledgment 587References 58716 Voltage Losses and Charge Transfer States in Donor–Acceptor Organic Solar Cells 591Hongbo Wu, Mengyang Li, Zaifei Ma, and Zheng Tang16.1 The Origin of Voc of Solar Cells 59116.1.1 Voltage Loss in an Ideal Solar Cell and the Upper Limit for Voc 59116.1.2 Voc and Voltage Loss in Non-ideal Solar Cells 59416.2 Voc of Organic Solar Cells 59616.2.1 Charge Transfer States in Organic Solar Cells 59616.2.2 Relation Between CT State and Voc of Organic Solar Cells 59716.2.3 Determining Factors of Kr and Knr for Organic Solar Cells 60116.2.4 Experimental Determination of CT State-Related Parameters 60416.3 Strategies to Reduce Vnr and Vr in Organic Solar Cells 60616.4 Summary 609Acknowledgments 610References 61017 Stability of Organic Solar Cells: From Fullerene Derivatives to Non-fullerene Acceptors 613Xiaoyan Du, Jing Guo, Jie Min, and Ning Li17.1 Introduction 61317.2 Factors Limiting the Stability of Organic Solar Cells 61417.2.1 Extrinsic Stresses 61417.2.1.1 Light Effect 61417.2.1.2 Thermal Effect 61517.2.1.3 Environmental Effect 61517.2.1.4 Mechanical Stress Effect 61517.2.2 Intrinsic Factors 61617.3 Stability Evaluation Protocols 61717.4 Progress in Developing Stable Organic Solar Cells 61817.4.1 Development of Organic Photovoltaic Materials with Stable Microstructure Morphology 61817.4.1.1 Organic Solar Cells Based on Fullerene Acceptors 62117.4.1.2 Organic Solar Cells Based on Non-fullerene Acceptors 62317.4.1.3 Organic Solar Cells Based on Polymeric Acceptors 62517.4.2 Strategies to Enhance the Morphological Stability of Organic Solar Cells 62517.4.2.1 Introducing Hydrogen Bonding in the Photo-Active Materials 62717.4.2.2 Chemically Linked Donor and Acceptor as a Single-Component Photoactive Layer 62717.4.2.3 Cross-Linking 62917.4.2.4 Solid Additives 63117.4.2.5 Solvent Additives 63117.4.2.6 Ternary and Multiple Composites 63317.4.2.7 Organic Nanoparticles 63317.4.2.8 Stratified Photoactive Layer Structure 63317.5 Recent Progress on Developing Organic Solar Cells with Excellent Stability 63517.6 Summary and Outlook 639References 64018 Potential Applications of Organic Solar Cells 645Chengyi Xiao and Weiwei Li18.1 Introduction 64518.2 Building-Integrated OSCs 64718.2.1 Solar Parks 64818.2.2 Smart Windows 65018.2.3 Solar Trees 65118.2.4 Greenhouse and Photosynthesis 65218.3 Wearable-Integrated OSCs 65518.3.1 Portable Device Photovoltaics 65518.3.2 Implantable and Wearable Self-Powered Sensors 65618.3.3 OSC Textile Toward Smart Clothing 65818.4 OSCs-Integrated Energy Storage System 66118.4.1 Planar Stacked OSCs-Integrated ESS 66218.4.2 Fiber-Based OSCs-Integrated ESS 66518.5 Other Applications 66618.5.1 OSCs-Driven Water Splitting 66618.5.2 OSCs-Integrated Glasses 66818.6 Conclusion and Outlook 668References 672Index 677