Nurdan Demirci Sankir is currently an Associate Professor in the Materials Science and Nanotechnology Engineering Department at the TOBB University of Economics and Technology, Ankara, Turkey. She received her M.Eng and PhD degrees in Materials Science and Engineering from the Virginia Polytechnic and State University, USA in 2005. She then joined NanoSonic Inc. in Virginia, USA as R&D engineer and program manager, and in 2007 she enrolled at TOBB ETU where she established the Energy Research and Solar Cell Laboratories. Nurdan has actively carried out research activities in many areas including solar driven water splitting, photocatalytic degradation and nanostructured semiconductors.Mehmet Sankir received his PhD in Macromolecular Science and Engineering from the Virginia Polytechnic and State University, USA in 2005. He is currently an Associate Professor in the Department of Materials Science and Nanotechnology Engineering, TOBB University of Economics and Technology, Ankara, Turkey and group leader of Advanced Membrane Technologies Laboratory. Mehmet has actively carried out research and consulting activities in the areas of membranes for fuel cells, flow batteries, hydrogen generation and desalination.

• Preface xvPart I Hybrid Materials and Process Technologies for Printable Solar Cells1 Organic and Inorganic Hybrid Solar Cells 3Serap Güneş and Niyazi Serdar Sariciftci1.1 Introduction 41.2 Organic/Inorganic Hybrid Solar Cells 51.2.1 Introduction to Hybrid Solar Cells 51.2.2 Hybrid Solar Cells 51.2.2.1 Operational Principles of BulkHeterojunction Hybrid Solar Cells 51.2.2.2 Bulk Heterojunction Hybrid Solar Cells 81.2.2.3 Bilayer Heterojunction Hybrid Solar Cells 121.2.2.4 Inverted-Type Hybrid Bulk Heterojunction Solar Cells 151.2.2.5 Dye-Sensitized Solar Cells 161.2.2.6 Perovskite Solar Cells 211.3 Conclusion  23References 252 Solution Processing and Thin Film Formation of Hybrid Semiconductors for Energy Applications 37J. Ciro, J.F. Montoya, R. Betancur and F. Jaramillo2.1 Physical Chemical Principles of Film Formation by Solution Processes: From Suspensions of Nanoparticles and Solutions to Nucleation, Growth, Coarsening and Microstructural Evolution of Films 382.2 Solution-Processing Techniques for Thin Film Deposition 402.2.1 Spin Coating 422.2.2 Doctor Blade 432.2.3 Slot-Die Coating 442.2.4 Spray Coating 462.3 Properties and Characterization of Thin Films: Transport, Active and Electrode Layers in Thin Film Solar Cells 462.4 Understanding the Crystallization Processes in Hybrid Semiconductor Films: Hybrid Perovskite as a Model 502.4.1 Thermal Transitions Revealed by DSC 502.4.2 Heat Transfer Processes in a Meso-Superstructured Perovskite Solar Cell 532.4.3 Effect of the Annealing Process on Morphology and Crystalline Properties of Perovskite Films 552.4.4 Role of Precursor Composition in the Crystallinity of Perovskite Films: Understanding the Role of Additives and Moisture in the Final Properties of Perovskite Layers 56References  573 Organic-Inorganic Hybrid Solar Cells Based on Quantum Dots 65Wenjin Yue3.1 Introduction 653.2 Polymer/QD Solar Cells 673.2.1 Working Principle 673.2.2 Device Parameters 683.2.2.1 Open-Circuit Voltage (Voc) 683.2.2.2 Short-Circuit Current (Jsc) 683.2.2.3 Fill Factor (FF) 693.2.3 Device Structure 703.2.4 Progress of Polymer/QD Solar Cells 713.2.4.1 Device Based on Cd Compound 713.2.4.2 Device Based on Pb Compound 743.2.4.3 Device Based on CuInS2 763.2.5 Strategy for Improved Device Performance 783.2.5.1 QDs Surface Treatment 783.2.5.2 In-Situ Synthesis of QDs 813.2.5.3 Polymer End-Group Functionalization 823.3 Outlooks and Conclusions 83Acknowledgment 834 Hole Transporting Layers in Printable Solar Cells 93David Curiel and Miriam Más-Montoya4.1 Introduction 944.2 Hole Transporting Layers in Organic Solar Cells 974.2.1 Utility of Hole Transporting Layers 974.2.1.1 Energy Level Alignment at the Interfaces and Effect on the Open-Circuit Voltage 984.1.1.2 Definition of Device Polarity, Charge Transport and Use as Blocking Layer 1024.1.1.3 Optical Spacer 1034.1.1.4 Modulation of the Active Layer Morphology and Use as Protective Layer 1034.1.2 Overview of Materials Used as Hole Transporting Layers 1044.1.2.1 Polymers 1044.1.2.2 Small Molecules 1094.1.2.3 Metals 1124.1.2.4 Metal Oxides 1124.1.2.5 Metal Salts 1164.1.2.6 Carbon Nanotubes 1164.1.2.7 Graphene-Based Materials 1164.1.2.8 Self-Assembled Monolayers 1194.2 Hole Transporting Layers in Dye-Sensitized Solar Cells 1214.2.1 Overview of Materials Used as Hole Transporting Layers 1234.2.1.1 Small Molecules 1234.2.1.2 Polymers 1264.3 Hole Transporting Layers in Perovskite Solar Cells 1274.3.1 Overview of Materials Used as Hole Transporting Layers 1284.3.1.1 Small Molecules 1284.3.1.2 Polymers 1374.3.1.3 Metal Oxides 1394.3.1.4 Metal Salts 1404.3.1.5 Carbon Nanotubes 1414.3.1.6 Graphene-Based Materials 1424.4 Concluding Remarks 1435 Printable Solar Cells 163Alexander Kovalenko and Michal Hrabal5.1 Introduction 1645.2 Printable Solar Cells Working Principles 1655.2.1 CIGS Solar Cells 1655.2.2 Perovskite Solar Cells 1675.2.3 Organic Solar Cells 1705.2.4 Printable Charge-Carrier Selective Layers 1725.3 Solution-Based Deposition of Thin Film Layers 1735.3.1 Coating Techniques 1745.3.1.1 Casting 1745.3.1.2 Spin Coating 1745.3.1.3 Blade Coating 1765.3.1.4 Slot-Die Coating 1775.3.2 Printing Techniques 1795.3.2.1 Screen Printing 1805.3.2.2 Gravure Printing 1825.3.2.3 Flexographic Printing 1845.3.2.4 Inkjet Printing 1855.4 Characterization Techniques 1895.4.1 Characterization of Thin Layers 1895.4.2 Electrical Characterization of Solar Cells 1905.5 Conclusion 194References 197Part II Organic Materials and Process Technologies for Printable Solar Cells6 Spray-Coated Organic Solar Cells 205Yifan Zheng and Junsheng Yu6.1 Introduction 2056.2 Introduction of Spray-Coating Method 2066.2.1 History of Spray Coating 2066.2.2 Spray-Coating Equipment 2066.2.2.1 Airbrush Spray Deposition 2066.2.2.2 Ultrasonic Spray Deposition 2096.2.2.3 Electrospray Deposition 2106.2.3 Spray-Coating Treatment 2126.2.3.1 Thermal Annealing 2136.2.3.2 Solvent Treatments 2146.3 Materials for Spray Coating 2166.3.1 Organic Materials 2166.3.2 Metal Oxide and Nanoparticles 2206.3.3 Perovskite 2226.4 Application of Spray Coating 2246.5 Conclusions 226Acknowledgment 226References 2267 Interface Engineering: A Key Aspect for the Potential Commercialization of Printable Organic Photovoltaic Cells 235Varun Vohra, Nur Tahirah Razali and Hideyuki Murata7.1 Introduction 2367.2 SD-PSCs Based on P3HT:PCBM Active Layers 2407.2.1 Increase in Donor-Acceptor Interface through Nanostructuration of SD-PSCs 2407.2.2 Generation of Vertical Concentration Gradient by Addition of Regiorandom P3HT in SD-PSCs 2427.2.3 Generation of Vertical Concentration Gradient and Molecular Orientation by Rubbing P3HT in SD-PSCs 2467.3 High Performance BHJ-PSCs with Favorable Molecular Orientation Resulting from Active Layer/SubstrateInteractions 2487.4 Strongly Bond Metal Leaves as Laminated Top Electrodes for Low-Cost PSC Fabrication 2527.5 Conclusions 257References 2588 Structural, Optical, Electrical and Electronic Properties of  PEDOT: PSS Thin Films and Their Application in Solar Cells 263Sheng Hsiung Chang, Cheng-Chiang Chen, Hsin-Ming Cheng and Sheng-Hui Chen8.1 Introduction 2648.2 Chemical Structure of PEDOT:PSS 2658.3 Optical and Electrical Characteristics of PEDOT:PSS 2678.4 Electronic Characteristics of PEDOT:PSS 2708.5 Highly Conductive PEDOT:PSS Thin Films 2718.6 Hole-Transporting Materials: PEDOT:PSS Thin Films 2738.6.1 Effect of PEDOT/PSS Ratio 2748.6.2 Effect of Spin Rate 2758.6.3 Effect of Thermal Annealing Temperature 2778.6.4 Effects of Viscosity of PEDOT:PSS Solutions 2788.7 Directions for Future Development 2818.8 Conclusion 282Reference 283Part III Perovskites and Process Technologies for Printable Solar Cells9 Organometal Trihalide Perovskite Absorbers: Optoelectronic Properties and Applications for Solar Cells 291Timur Sh. Atabaev and Nguyen Hoa Hong9.1 Introduction 2919.2 Optical Properties of Organic-Inorganic Perovskite Materials 2939.3 Charge Transport Properties 2949.4 Electron Transporting Materials (ETM) 2959.5 Hole-Transporting Materials (HTM) 2959.6 Perovskite Solar Cells Architectures 2969.7 Perovskite Deposition Methods 2989.8 Photoexcited States 3009.9 Hysteresis 3009.10 Stability in Humid Environment 3029.11 Stability Under UV Light Exposure 3029.12 Stability at High Temperatures 3039.13 Additives 3049.14 Conclusions and Outlook 305Acknowledgment 306References 30610 Organic-Inorganic Hybrid Perovskite Solar Cells with Scalable and Roll-to-Roll Compatible Printing/Coating Processes 313Dechan Angmo, Mei Gao and Doojin Vak10.1 Introduction 31410.2 Optoelectronic Properties 31610.3 History 31710.4 Device Configurations 31810.5 Functional Materials 32110.5.1 The Organic-Inorganic Halide Perovskites 32210.5.2 Electron-Selective Layer 32410.5.3 Hole-Selective Layer 32510.5.4 Transparent Electrode 32510.5.5 Counter Electrode 32610.6 Spin Coating 32710.7 Roll-to-Roll Processing 33110.8 Substrate Limitation 33110.9 Printing and Coating Methods 33310.9.1 Coating Methods 33510.9.1.1 Slot-Die Coating 33510.9.1.2 Spray Coating 33910.9.1.3 Doctor Blade Coating 34210.9.1.4 Knife Coating 34410.9.1.5 Reverse Gravure Coating 34510.9.2 Printing Methods 34610.9.2.1 Gravure Printing 34610.9.2.2 Flexographic Printing 34710.9.2.3 Screen Printing 34910.9.2.4 Inkjet Printing 35010.10 Future Outlook 352References 35211 Inkjet Printable Processes for Dye-Sensitized and Perovskite Solar Cells and Modules Based on Advanced Nanocomposite Materials 363Theodoros Makris, Argyroula Mourtzikou, Andreas Rapsomanikis and Elias Stathatos11.1 Introduction 36411.1.1 Dye-Sensitized Solar Cells 36411.1.2 Perovskite Solar Cells 36711.2 Inkjet Printing Process 36911.2.1 Inkjet Printing in DSSC Technology 37011.2.1.1 Inkjet Printing of Transition Metal Oxides 37211.2.1.2 Inkjet Printing of Dyes on Semiconducting Oxides 37311.2.1.3 Inkjet Printing of Ionic Liquid-Based Electrolytes 37411.2.2 Inkjet Printing in Perovskite Solar Cell Technology 37711.2.2.1 Inkjet Printing of Perovskite Material 37811.3 Conclusions 379References 379Part IV Inorganic Materials and Process Technologies for Printable Solar Cells 38312 Solution-Processed Kesterite Solar Cells 385Fangyang Liu12.1 Introduction 38512.2 Fundamental Aspects of Kesterite Solar Cells 38612.2.1 Crystal Structure 38612.2.2 Phase Space and Secondary Phases 38812.2.3 Optical and Electrical Properties 39012.2.4 Device Architecture 39112.3 Keterite Absorber Deposition Strategies 39312.4 Electrodeposition 39512.4.1 Stacked Elemental Layer (SEL) Electrodeposition 39612.4.2 Metallic Alloy Co-electrodeposition 39812.4.3 Chalcogenide Co-electrodeposition 39912.5 Direct Solution Coating 40012.5.1 Hydrazine Solution Coating 40112.5.2 Particulate-Based Solution Coating 40212.5.3 Molecular-Based Solution Coating 40512.6 Conclusion 409References 40913 Inorganic Hole Contacts for Perovskite Solar Cells: Towards High-Performance Printable Solar Cells 423Xingtian Yin and Wenxiu Que13.1 Introduction 42413.2 Transition Metal Oxides 42613.2.1 Molybdenum Oxide (MoOx, x < 3) 42613.2.2 Nickel Oxide (NiO) 42813.2.2.1 Mesoscopic NiO Perovskite Solar Cells 42813.2.2.2 Planar NiO Perovskite Solar Cells 42913.2.3 Binary Copper Oxide (CuO and Cu2O) 43913.2.4 Other Transition Metal Oxides 44013.3 Non-Oxide Copper Compounds 44013.3.1 Cuprous Iodide (CuI) 44113.3.2 Cuprous Rhodanide (CuSCN) 44113.3.3 Copper Sulfide (CuS) 44213.3.4 CuAlO2 44313.3.5 CuInS2 and Cu2ZnSnS4 44413.4 Other Inorganic HTMs 44413.4.1 PdS Quantum Dots (QDs)  44413.4.2 Two-Dimensional (2D) Materials  44513.5 Towards Printable Solar Cells  44613.6 Conclusions and Perspectives  449Acknowledgment 450References 45014 Electrode Materials for Printable Solar Cells 457Lijun Hu, Ke Yang, Wei Chen, Falin Wu, Jiehao Fu, Wenbo Sun, Hongyan Huang, Baomin Zhao, Kuan Sun and Jianyong Ouyang14.1 Introduction 45814.2 Transparent Conjugated Polymers 45914.2.1 Solvent Additive Method 46014.2.2 Post-Treatment of PEDOT:PSS Films 46114.2.3 Printing PEDOT:PSS Inks 46314.3 Carbon-Based Nanomaterials 46314.3.1 Graphene 46614.3.2 Carbon Nanotubes 47214.4 Metallic Nanostructures 47614.4.1 Metal Nanomeshes 47614.4.2 Metal Nanowire Networks 48014.4.3 Ultrathin Metal Films 48214.5 Multilayer Thin Films 48614.6 Printable Metal Back Electrodes 49114.7 Carbon-Based Back Electrodes 49414.8 Summary and Outlook 497Acknowledgment 498References 49815 Photonic Crystals for Photon Management in Solar Cells 513Shuai Zhang, Zhongze Gu and Jian-Ning Ding15.1 Introduction 51315.2 Fundamentals of PCs 51515.3 Fabrication Strategies of PCs for Photovoltaics 51815.3.1 1D Multilayer PCs 51915.3.2 2D PCs 52415.3.3 3D PCs 52715.4 Different Functionalities of PCs in Solar Cells 53015.4.1 PC Reflectors 53115.4.2 PC Absorbers 53515.4.3 Front-Side PCs 53815.4.4 PCs for Other Functionalities 54015.5 Summary and Outlook 540Acknowledgment 542References 542

Nurdan Demirci Sankir is currently an Associate Professor in the Materials Science and Nanotechnology Engineering Department at the TOBB University of Economics and Technology, Ankara, Turkey. She received her M.Eng and PhD degrees in Materials Science and Engineering from the Virginia Polytechnic and State University, USA in 2005. She then joined NanoSonic Inc. in Virginia, USA as R&D engineer and program manager, and in 2007 she enrolled at TOBB ETU where she established the Energy Research and Solar Cell Laboratories. Nurdan has actively carried out research activities in many areas including solar driven water splitting, photocatalytic degradation and nanostructured semiconductors.Mehmet Sankir received his PhD in Macromolecular Science and Engineering from the Virginia Polytechnic and State University, USA in 2005. He is currently an Associate Professor in the Department of Materials Science and Nanotechnology Engineering, TOBB University of Economics and Technology, Ankara, Turkey and group leader of Advanced Membrane Technologies Laboratory. Mehmet has actively carried out research and consulting activities in the areas of membranes for fuel cells, flow batteries, hydrogen generation and desalination.

• Preface xvPart I Hybrid Materials and Process Technologies for Printable Solar Cells1 Organic and Inorganic Hybrid Solar Cells 3Serap Güneş and Niyazi Serdar Sariciftci1.1 Introduction 41.2 Organic/Inorganic Hybrid Solar Cells 51.2.1 Introduction to Hybrid Solar Cells 51.2.2 Hybrid Solar Cells 51.2.2.1 Operational Principles of BulkHeterojunction Hybrid Solar Cells 51.2.2.2 Bulk Heterojunction Hybrid Solar Cells 81.2.2.3 Bilayer Heterojunction Hybrid Solar Cells 121.2.2.4 Inverted-Type Hybrid Bulk Heterojunction Solar Cells 151.2.2.5 Dye-Sensitized Solar Cells 161.2.2.6 Perovskite Solar Cells 211.3 Conclusion  23References 252 Solution Processing and Thin Film Formation of Hybrid Semiconductors for Energy Applications 37J. Ciro, J.F. Montoya, R. Betancur and F. Jaramillo2.1 Physical Chemical Principles of Film Formation by Solution Processes: From Suspensions of Nanoparticles and Solutions to Nucleation, Growth, Coarsening and Microstructural Evolution of Films 382.2 Solution-Processing Techniques for Thin Film Deposition 402.2.1 Spin Coating 422.2.2 Doctor Blade 432.2.3 Slot-Die Coating 442.2.4 Spray Coating 462.3 Properties and Characterization of Thin Films: Transport, Active and Electrode Layers in Thin Film Solar Cells 462.4 Understanding the Crystallization Processes in Hybrid Semiconductor Films: Hybrid Perovskite as a Model 502.4.1 Thermal Transitions Revealed by DSC 502.4.2 Heat Transfer Processes in a Meso-Superstructured Perovskite Solar Cell 532.4.3 Effect of the Annealing Process on Morphology and Crystalline Properties of Perovskite Films 552.4.4 Role of Precursor Composition in the Crystallinity of Perovskite Films: Understanding the Role of Additives and Moisture in the Final Properties of Perovskite Layers 56References  573 Organic-Inorganic Hybrid Solar Cells Based on Quantum Dots 65Wenjin Yue3.1 Introduction 653.2 Polymer/QD Solar Cells 673.2.1 Working Principle 673.2.2 Device Parameters 683.2.2.1 Open-Circuit Voltage (Voc) 683.2.2.2 Short-Circuit Current (Jsc) 683.2.2.3 Fill Factor (FF) 693.2.3 Device Structure 703.2.4 Progress of Polymer/QD Solar Cells 713.2.4.1 Device Based on Cd Compound 713.2.4.2 Device Based on Pb Compound 743.2.4.3 Device Based on CuInS2 763.2.5 Strategy for Improved Device Performance 783.2.5.1 QDs Surface Treatment 783.2.5.2 In-Situ Synthesis of QDs 813.2.5.3 Polymer End-Group Functionalization 823.3 Outlooks and Conclusions 83Acknowledgment 834 Hole Transporting Layers in Printable Solar Cells 93David Curiel and Miriam Más-Montoya4.1 Introduction 944.2 Hole Transporting Layers in Organic Solar Cells 974.2.1 Utility of Hole Transporting Layers 974.2.1.1 Energy Level Alignment at the Interfaces and Effect on the Open-Circuit Voltage 984.1.1.2 Definition of Device Polarity, Charge Transport and Use as Blocking Layer 1024.1.1.3 Optical Spacer 1034.1.1.4 Modulation of the Active Layer Morphology and Use as Protective Layer 1034.1.2 Overview of Materials Used as Hole Transporting Layers 1044.1.2.1 Polymers 1044.1.2.2 Small Molecules 1094.1.2.3 Metals 1124.1.2.4 Metal Oxides 1124.1.2.5 Metal Salts 1164.1.2.6 Carbon Nanotubes 1164.1.2.7 Graphene-Based Materials 1164.1.2.8 Self-Assembled Monolayers 1194.2 Hole Transporting Layers in Dye-Sensitized Solar Cells 1214.2.1 Overview of Materials Used as Hole Transporting Layers 1234.2.1.1 Small Molecules 1234.2.1.2 Polymers 1264.3 Hole Transporting Layers in Perovskite Solar Cells 1274.3.1 Overview of Materials Used as Hole Transporting Layers 1284.3.1.1 Small Molecules 1284.3.1.2 Polymers 1374.3.1.3 Metal Oxides 1394.3.1.4 Metal Salts 1404.3.1.5 Carbon Nanotubes 1414.3.1.6 Graphene-Based Materials 1424.4 Concluding Remarks 1435 Printable Solar Cells 163Alexander Kovalenko and Michal Hrabal5.1 Introduction 1645.2 Printable Solar Cells Working Principles 1655.2.1 CIGS Solar Cells 1655.2.2 Perovskite Solar Cells 1675.2.3 Organic Solar Cells 1705.2.4 Printable Charge-Carrier Selective Layers 1725.3 Solution-Based Deposition of Thin Film Layers 1735.3.1 Coating Techniques 1745.3.1.1 Casting 1745.3.1.2 Spin Coating 1745.3.1.3 Blade Coating 1765.3.1.4 Slot-Die Coating 1775.3.2 Printing Techniques 1795.3.2.1 Screen Printing 1805.3.2.2 Gravure Printing 1825.3.2.3 Flexographic Printing 1845.3.2.4 Inkjet Printing 1855.4 Characterization Techniques 1895.4.1 Characterization of Thin Layers 1895.4.2 Electrical Characterization of Solar Cells 1905.5 Conclusion 194References 197Part II Organic Materials and Process Technologies for Printable Solar Cells6 Spray-Coated Organic Solar Cells 205Yifan Zheng and Junsheng Yu6.1 Introduction 2056.2 Introduction of Spray-Coating Method 2066.2.1 History of Spray Coating 2066.2.2 Spray-Coating Equipment 2066.2.2.1 Airbrush Spray Deposition 2066.2.2.2 Ultrasonic Spray Deposition 2096.2.2.3 Electrospray Deposition 2106.2.3 Spray-Coating Treatment 2126.2.3.1 Thermal Annealing 2136.2.3.2 Solvent Treatments 2146.3 Materials for Spray Coating 2166.3.1 Organic Materials 2166.3.2 Metal Oxide and Nanoparticles 2206.3.3 Perovskite 2226.4 Application of Spray Coating 2246.5 Conclusions 226Acknowledgment 226References 2267 Interface Engineering: A Key Aspect for the Potential Commercialization of Printable Organic Photovoltaic Cells 235Varun Vohra, Nur Tahirah Razali and Hideyuki Murata7.1 Introduction 2367.2 SD-PSCs Based on P3HT:PCBM Active Layers 2407.2.1 Increase in Donor-Acceptor Interface through Nanostructuration of SD-PSCs 2407.2.2 Generation of Vertical Concentration Gradient by Addition of Regiorandom P3HT in SD-PSCs 2427.2.3 Generation of Vertical Concentration Gradient and Molecular Orientation by Rubbing P3HT in SD-PSCs 2467.3 High Performance BHJ-PSCs with Favorable Molecular Orientation Resulting from Active Layer/SubstrateInteractions 2487.4 Strongly Bond Metal Leaves as Laminated Top Electrodes for Low-Cost PSC Fabrication 2527.5 Conclusions 257References 2588 Structural, Optical, Electrical and Electronic Properties of  PEDOT: PSS Thin Films and Their Application in Solar Cells 263Sheng Hsiung Chang, Cheng-Chiang Chen, Hsin-Ming Cheng and Sheng-Hui Chen8.1 Introduction 2648.2 Chemical Structure of PEDOT:PSS 2658.3 Optical and Electrical Characteristics of PEDOT:PSS 2678.4 Electronic Characteristics of PEDOT:PSS 2708.5 Highly Conductive PEDOT:PSS Thin Films 2718.6 Hole-Transporting Materials: PEDOT:PSS Thin Films 2738.6.1 Effect of PEDOT/PSS Ratio 2748.6.2 Effect of Spin Rate 2758.6.3 Effect of Thermal Annealing Temperature 2778.6.4 Effects of Viscosity of PEDOT:PSS Solutions 2788.7 Directions for Future Development 2818.8 Conclusion 282Reference 283Part III Perovskites and Process Technologies for Printable Solar Cells9 Organometal Trihalide Perovskite Absorbers: Optoelectronic Properties and Applications for Solar Cells 291Timur Sh. Atabaev and Nguyen Hoa Hong9.1 Introduction 2919.2 Optical Properties of Organic-Inorganic Perovskite Materials 2939.3 Charge Transport Properties 2949.4 Electron Transporting Materials (ETM) 2959.5 Hole-Transporting Materials (HTM) 2959.6 Perovskite Solar Cells Architectures 2969.7 Perovskite Deposition Methods 2989.8 Photoexcited States 3009.9 Hysteresis 3009.10 Stability in Humid Environment 3029.11 Stability Under UV Light Exposure 3029.12 Stability at High Temperatures 3039.13 Additives 3049.14 Conclusions and Outlook 305Acknowledgment 306References 30610 Organic-Inorganic Hybrid Perovskite Solar Cells with Scalable and Roll-to-Roll Compatible Printing/Coating Processes 313Dechan Angmo, Mei Gao and Doojin Vak10.1 Introduction 31410.2 Optoelectronic Properties 31610.3 History 31710.4 Device Configurations 31810.5 Functional Materials 32110.5.1 The Organic-Inorganic Halide Perovskites 32210.5.2 Electron-Selective Layer 32410.5.3 Hole-Selective Layer 32510.5.4 Transparent Electrode 32510.5.5 Counter Electrode 32610.6 Spin Coating 32710.7 Roll-to-Roll Processing 33110.8 Substrate Limitation 33110.9 Printing and Coating Methods 33310.9.1 Coating Methods 33510.9.1.1 Slot-Die Coating 33510.9.1.2 Spray Coating 33910.9.1.3 Doctor Blade Coating 34210.9.1.4 Knife Coating 34410.9.1.5 Reverse Gravure Coating 34510.9.2 Printing Methods 34610.9.2.1 Gravure Printing 34610.9.2.2 Flexographic Printing 34710.9.2.3 Screen Printing 34910.9.2.4 Inkjet Printing 35010.10 Future Outlook 352References 35211 Inkjet Printable Processes for Dye-Sensitized and Perovskite Solar Cells and Modules Based on Advanced Nanocomposite Materials 363Theodoros Makris, Argyroula Mourtzikou, Andreas Rapsomanikis and Elias Stathatos11.1 Introduction 36411.1.1 Dye-Sensitized Solar Cells 36411.1.2 Perovskite Solar Cells 36711.2 Inkjet Printing Process 36911.2.1 Inkjet Printing in DSSC Technology 37011.2.1.1 Inkjet Printing of Transition Metal Oxides 37211.2.1.2 Inkjet Printing of Dyes on Semiconducting Oxides 37311.2.1.3 Inkjet Printing of Ionic Liquid-Based Electrolytes 37411.2.2 Inkjet Printing in Perovskite Solar Cell Technology 37711.2.2.1 Inkjet Printing of Perovskite Material 37811.3 Conclusions 379References 379Part IV Inorganic Materials and Process Technologies for Printable Solar Cells 38312 Solution-Processed Kesterite Solar Cells 385Fangyang Liu12.1 Introduction 38512.2 Fundamental Aspects of Kesterite Solar Cells 38612.2.1 Crystal Structure 38612.2.2 Phase Space and Secondary Phases 38812.2.3 Optical and Electrical Properties 39012.2.4 Device Architecture 39112.3 Keterite Absorber Deposition Strategies 39312.4 Electrodeposition 39512.4.1 Stacked Elemental Layer (SEL) Electrodeposition 39612.4.2 Metallic Alloy Co-electrodeposition 39812.4.3 Chalcogenide Co-electrodeposition 39912.5 Direct Solution Coating 40012.5.1 Hydrazine Solution Coating 40112.5.2 Particulate-Based Solution Coating 40212.5.3 Molecular-Based Solution Coating 40512.6 Conclusion 409References 40913 Inorganic Hole Contacts for Perovskite Solar Cells: Towards High-Performance Printable Solar Cells 423Xingtian Yin and Wenxiu Que13.1 Introduction 42413.2 Transition Metal Oxides 42613.2.1 Molybdenum Oxide (MoOx, x < 3) 42613.2.2 Nickel Oxide (NiO) 42813.2.2.1 Mesoscopic NiO Perovskite Solar Cells 42813.2.2.2 Planar NiO Perovskite Solar Cells 42913.2.3 Binary Copper Oxide (CuO and Cu2O) 43913.2.4 Other Transition Metal Oxides 44013.3 Non-Oxide Copper Compounds 44013.3.1 Cuprous Iodide (CuI) 44113.3.2 Cuprous Rhodanide (CuSCN) 44113.3.3 Copper Sulfide (CuS) 44213.3.4 CuAlO2 44313.3.5 CuInS2 and Cu2ZnSnS4 44413.4 Other Inorganic HTMs 44413.4.1 PdS Quantum Dots (QDs)  44413.4.2 Two-Dimensional (2D) Materials  44513.5 Towards Printable Solar Cells  44613.6 Conclusions and Perspectives  449Acknowledgment 450References 45014 Electrode Materials for Printable Solar Cells 457Lijun Hu, Ke Yang, Wei Chen, Falin Wu, Jiehao Fu, Wenbo Sun, Hongyan Huang, Baomin Zhao, Kuan Sun and Jianyong Ouyang14.1 Introduction 45814.2 Transparent Conjugated Polymers 45914.2.1 Solvent Additive Method 46014.2.2 Post-Treatment of PEDOT:PSS Films 46114.2.3 Printing PEDOT:PSS Inks 46314.3 Carbon-Based Nanomaterials 46314.3.1 Graphene 46614.3.2 Carbon Nanotubes 47214.4 Metallic Nanostructures 47614.4.1 Metal Nanomeshes 47614.4.2 Metal Nanowire Networks 48014.4.3 Ultrathin Metal Films 48214.5 Multilayer Thin Films 48614.6 Printable Metal Back Electrodes 49114.7 Carbon-Based Back Electrodes 49414.8 Summary and Outlook 497Acknowledgment 498References 49815 Photonic Crystals for Photon Management in Solar Cells 513Shuai Zhang, Zhongze Gu and Jian-Ning Ding15.1 Introduction 51315.2 Fundamentals of PCs 51515.3 Fabrication Strategies of PCs for Photovoltaics 51815.3.1 1D Multilayer PCs 51915.3.2 2D PCs 52415.3.3 3D PCs 52715.4 Different Functionalities of PCs in Solar Cells 53015.4.1 PC Reflectors 53115.4.2 PC Absorbers 53515.4.3 Front-Side PCs 53815.4.4 PCs for Other Functionalities 54015.5 Summary and Outlook 540Acknowledgment 542References 542

Nurdan Demirci Sankir is currently an Associate Professor in the Materials Science and Nanotechnology Engineering Department at the TOBB University of Economics and Technology, Ankara, Turkey. She received her M.Eng and PhD degrees in Materials Science and Engineering from the Virginia Polytechnic and State University, USA in 2005. She then joined NanoSonic Inc. in Virginia, USA as R&D engineer and program manager, and in 2007 she enrolled at TOBB ETU where she established the Energy Research and Solar Cell Laboratories. Nurdan has actively carried out research activities in many areas including solar driven water splitting, photocatalytic degradation and nanostructured semiconductors.Mehmet Sankir received his PhD in Macromolecular Science and Engineering from the Virginia Polytechnic and State University, USA in 2005. He is currently an Associate Professor in the Department of Materials Science and Nanotechnology Engineering, TOBB University of Economics and Technology, Ankara, Turkey and group leader of Advanced Membrane Technologies Laboratory. Mehmet has actively carried out research and consulting activities in the areas of membranes for fuel cells, flow batteries, hydrogen generation and desalination.

• Preface xvPart I Hybrid Materials and Process Technologies for Printable Solar Cells1 Organic and Inorganic Hybrid Solar Cells 3Serap Güneş and Niyazi Serdar Sariciftci1.1 Introduction 41.2 Organic/Inorganic Hybrid Solar Cells 51.2.1 Introduction to Hybrid Solar Cells 51.2.2 Hybrid Solar Cells 51.2.2.1 Operational Principles of BulkHeterojunction Hybrid Solar Cells 51.2.2.2 Bulk Heterojunction Hybrid Solar Cells 81.2.2.3 Bilayer Heterojunction Hybrid Solar Cells 121.2.2.4 Inverted-Type Hybrid Bulk Heterojunction Solar Cells 151.2.2.5 Dye-Sensitized Solar Cells 161.2.2.6 Perovskite Solar Cells 211.3 Conclusion  23References 252 Solution Processing and Thin Film Formation of Hybrid Semiconductors for Energy Applications 37J. Ciro, J.F. Montoya, R. Betancur and F. Jaramillo2.1 Physical Chemical Principles of Film Formation by Solution Processes: From Suspensions of Nanoparticles and Solutions to Nucleation, Growth, Coarsening and Microstructural Evolution of Films 382.2 Solution-Processing Techniques for Thin Film Deposition 402.2.1 Spin Coating 422.2.2 Doctor Blade 432.2.3 Slot-Die Coating 442.2.4 Spray Coating 462.3 Properties and Characterization of Thin Films: Transport, Active and Electrode Layers in Thin Film Solar Cells 462.4 Understanding the Crystallization Processes in Hybrid Semiconductor Films: Hybrid Perovskite as a Model 502.4.1 Thermal Transitions Revealed by DSC 502.4.2 Heat Transfer Processes in a Meso-Superstructured Perovskite Solar Cell 532.4.3 Effect of the Annealing Process on Morphology and Crystalline Properties of Perovskite Films 552.4.4 Role of Precursor Composition in the Crystallinity of Perovskite Films: Understanding the Role of Additives and Moisture in the Final Properties of Perovskite Layers 56References  573 Organic-Inorganic Hybrid Solar Cells Based on Quantum Dots 65Wenjin Yue3.1 Introduction 653.2 Polymer/QD Solar Cells 673.2.1 Working Principle 673.2.2 Device Parameters 683.2.2.1 Open-Circuit Voltage (Voc) 683.2.2.2 Short-Circuit Current (Jsc) 683.2.2.3 Fill Factor (FF) 693.2.3 Device Structure 703.2.4 Progress of Polymer/QD Solar Cells 713.2.4.1 Device Based on Cd Compound 713.2.4.2 Device Based on Pb Compound 743.2.4.3 Device Based on CuInS2 763.2.5 Strategy for Improved Device Performance 783.2.5.1 QDs Surface Treatment 783.2.5.2 In-Situ Synthesis of QDs 813.2.5.3 Polymer End-Group Functionalization 823.3 Outlooks and Conclusions 83Acknowledgment 834 Hole Transporting Layers in Printable Solar Cells 93David Curiel and Miriam Más-Montoya4.1 Introduction 944.2 Hole Transporting Layers in Organic Solar Cells 974.2.1 Utility of Hole Transporting Layers 974.2.1.1 Energy Level Alignment at the Interfaces and Effect on the Open-Circuit Voltage 984.1.1.2 Definition of Device Polarity, Charge Transport and Use as Blocking Layer 1024.1.1.3 Optical Spacer 1034.1.1.4 Modulation of the Active Layer Morphology and Use as Protective Layer 1034.1.2 Overview of Materials Used as Hole Transporting Layers 1044.1.2.1 Polymers 1044.1.2.2 Small Molecules 1094.1.2.3 Metals 1124.1.2.4 Metal Oxides 1124.1.2.5 Metal Salts 1164.1.2.6 Carbon Nanotubes 1164.1.2.7 Graphene-Based Materials 1164.1.2.8 Self-Assembled Monolayers 1194.2 Hole Transporting Layers in Dye-Sensitized Solar Cells 1214.2.1 Overview of Materials Used as Hole Transporting Layers 1234.2.1.1 Small Molecules 1234.2.1.2 Polymers 1264.3 Hole Transporting Layers in Perovskite Solar Cells 1274.3.1 Overview of Materials Used as Hole Transporting Layers 1284.3.1.1 Small Molecules 1284.3.1.2 Polymers 1374.3.1.3 Metal Oxides 1394.3.1.4 Metal Salts 1404.3.1.5 Carbon Nanotubes 1414.3.1.6 Graphene-Based Materials 1424.4 Concluding Remarks 1435 Printable Solar Cells 163Alexander Kovalenko and Michal Hrabal5.1 Introduction 1645.2 Printable Solar Cells Working Principles 1655.2.1 CIGS Solar Cells 1655.2.2 Perovskite Solar Cells 1675.2.3 Organic Solar Cells 1705.2.4 Printable Charge-Carrier Selective Layers 1725.3 Solution-Based Deposition of Thin Film Layers 1735.3.1 Coating Techniques 1745.3.1.1 Casting 1745.3.1.2 Spin Coating 1745.3.1.3 Blade Coating 1765.3.1.4 Slot-Die Coating 1775.3.2 Printing Techniques 1795.3.2.1 Screen Printing 1805.3.2.2 Gravure Printing 1825.3.2.3 Flexographic Printing 1845.3.2.4 Inkjet Printing 1855.4 Characterization Techniques 1895.4.1 Characterization of Thin Layers 1895.4.2 Electrical Characterization of Solar Cells 1905.5 Conclusion 194References 197Part II Organic Materials and Process Technologies for Printable Solar Cells6 Spray-Coated Organic Solar Cells 205Yifan Zheng and Junsheng Yu6.1 Introduction 2056.2 Introduction of Spray-Coating Method 2066.2.1 History of Spray Coating 2066.2.2 Spray-Coating Equipment 2066.2.2.1 Airbrush Spray Deposition 2066.2.2.2 Ultrasonic Spray Deposition 2096.2.2.3 Electrospray Deposition 2106.2.3 Spray-Coating Treatment 2126.2.3.1 Thermal Annealing 2136.2.3.2 Solvent Treatments 2146.3 Materials for Spray Coating 2166.3.1 Organic Materials 2166.3.2 Metal Oxide and Nanoparticles 2206.3.3 Perovskite 2226.4 Application of Spray Coating 2246.5 Conclusions 226Acknowledgment 226References 2267 Interface Engineering: A Key Aspect for the Potential Commercialization of Printable Organic Photovoltaic Cells 235Varun Vohra, Nur Tahirah Razali and Hideyuki Murata7.1 Introduction 2367.2 SD-PSCs Based on P3HT:PCBM Active Layers 2407.2.1 Increase in Donor-Acceptor Interface through Nanostructuration of SD-PSCs 2407.2.2 Generation of Vertical Concentration Gradient by Addition of Regiorandom P3HT in SD-PSCs 2427.2.3 Generation of Vertical Concentration Gradient and Molecular Orientation by Rubbing P3HT in SD-PSCs 2467.3 High Performance BHJ-PSCs with Favorable Molecular Orientation Resulting from Active Layer/SubstrateInteractions 2487.4 Strongly Bond Metal Leaves as Laminated Top Electrodes for Low-Cost PSC Fabrication 2527.5 Conclusions 257References 2588 Structural, Optical, Electrical and Electronic Properties of  PEDOT: PSS Thin Films and Their Application in Solar Cells 263Sheng Hsiung Chang, Cheng-Chiang Chen, Hsin-Ming Cheng and Sheng-Hui Chen8.1 Introduction 2648.2 Chemical Structure of PEDOT:PSS 2658.3 Optical and Electrical Characteristics of PEDOT:PSS 2678.4 Electronic Characteristics of PEDOT:PSS 2708.5 Highly Conductive PEDOT:PSS Thin Films 2718.6 Hole-Transporting Materials: PEDOT:PSS Thin Films 2738.6.1 Effect of PEDOT/PSS Ratio 2748.6.2 Effect of Spin Rate 2758.6.3 Effect of Thermal Annealing Temperature 2778.6.4 Effects of Viscosity of PEDOT:PSS Solutions 2788.7 Directions for Future Development 2818.8 Conclusion 282Reference 283Part III Perovskites and Process Technologies for Printable Solar Cells9 Organometal Trihalide Perovskite Absorbers: Optoelectronic Properties and Applications for Solar Cells 291Timur Sh. Atabaev and Nguyen Hoa Hong9.1 Introduction 2919.2 Optical Properties of Organic-Inorganic Perovskite Materials 2939.3 Charge Transport Properties 2949.4 Electron Transporting Materials (ETM) 2959.5 Hole-Transporting Materials (HTM) 2959.6 Perovskite Solar Cells Architectures 2969.7 Perovskite Deposition Methods 2989.8 Photoexcited States 3009.9 Hysteresis 3009.10 Stability in Humid Environment 3029.11 Stability Under UV Light Exposure 3029.12 Stability at High Temperatures 3039.13 Additives 3049.14 Conclusions and Outlook 305Acknowledgment 306References 30610 Organic-Inorganic Hybrid Perovskite Solar Cells with Scalable and Roll-to-Roll Compatible Printing/Coating Processes 313Dechan Angmo, Mei Gao and Doojin Vak10.1 Introduction 31410.2 Optoelectronic Properties 31610.3 History 31710.4 Device Configurations 31810.5 Functional Materials 32110.5.1 The Organic-Inorganic Halide Perovskites 32210.5.2 Electron-Selective Layer 32410.5.3 Hole-Selective Layer 32510.5.4 Transparent Electrode 32510.5.5 Counter Electrode 32610.6 Spin Coating 32710.7 Roll-to-Roll Processing 33110.8 Substrate Limitation 33110.9 Printing and Coating Methods 33310.9.1 Coating Methods 33510.9.1.1 Slot-Die Coating 33510.9.1.2 Spray Coating 33910.9.1.3 Doctor Blade Coating 34210.9.1.4 Knife Coating 34410.9.1.5 Reverse Gravure Coating 34510.9.2 Printing Methods 34610.9.2.1 Gravure Printing 34610.9.2.2 Flexographic Printing 34710.9.2.3 Screen Printing 34910.9.2.4 Inkjet Printing 35010.10 Future Outlook 352References 35211 Inkjet Printable Processes for Dye-Sensitized and Perovskite Solar Cells and Modules Based on Advanced Nanocomposite Materials 363Theodoros Makris, Argyroula Mourtzikou, Andreas Rapsomanikis and Elias Stathatos11.1 Introduction 36411.1.1 Dye-Sensitized Solar Cells 36411.1.2 Perovskite Solar Cells 36711.2 Inkjet Printing Process 36911.2.1 Inkjet Printing in DSSC Technology 37011.2.1.1 Inkjet Printing of Transition Metal Oxides 37211.2.1.2 Inkjet Printing of Dyes on Semiconducting Oxides 37311.2.1.3 Inkjet Printing of Ionic Liquid-Based Electrolytes 37411.2.2 Inkjet Printing in Perovskite Solar Cell Technology 37711.2.2.1 Inkjet Printing of Perovskite Material 37811.3 Conclusions 379References 379Part IV Inorganic Materials and Process Technologies for Printable Solar Cells 38312 Solution-Processed Kesterite Solar Cells 385Fangyang Liu12.1 Introduction 38512.2 Fundamental Aspects of Kesterite Solar Cells 38612.2.1 Crystal Structure 38612.2.2 Phase Space and Secondary Phases 38812.2.3 Optical and Electrical Properties 39012.2.4 Device Architecture 39112.3 Keterite Absorber Deposition Strategies 39312.4 Electrodeposition 39512.4.1 Stacked Elemental Layer (SEL) Electrodeposition 39612.4.2 Metallic Alloy Co-electrodeposition 39812.4.3 Chalcogenide Co-electrodeposition 39912.5 Direct Solution Coating 40012.5.1 Hydrazine Solution Coating 40112.5.2 Particulate-Based Solution Coating 40212.5.3 Molecular-Based Solution Coating 40512.6 Conclusion 409References 40913 Inorganic Hole Contacts for Perovskite Solar Cells: Towards High-Performance Printable Solar Cells 423Xingtian Yin and Wenxiu Que13.1 Introduction 42413.2 Transition Metal Oxides 42613.2.1 Molybdenum Oxide (MoOx, x < 3) 42613.2.2 Nickel Oxide (NiO) 42813.2.2.1 Mesoscopic NiO Perovskite Solar Cells 42813.2.2.2 Planar NiO Perovskite Solar Cells 42913.2.3 Binary Copper Oxide (CuO and Cu2O) 43913.2.4 Other Transition Metal Oxides 44013.3 Non-Oxide Copper Compounds 44013.3.1 Cuprous Iodide (CuI) 44113.3.2 Cuprous Rhodanide (CuSCN) 44113.3.3 Copper Sulfide (CuS) 44213.3.4 CuAlO2 44313.3.5 CuInS2 and Cu2ZnSnS4 44413.4 Other Inorganic HTMs 44413.4.1 PdS Quantum Dots (QDs)  44413.4.2 Two-Dimensional (2D) Materials  44513.5 Towards Printable Solar Cells  44613.6 Conclusions and Perspectives  449Acknowledgment 450References 45014 Electrode Materials for Printable Solar Cells 457Lijun Hu, Ke Yang, Wei Chen, Falin Wu, Jiehao Fu, Wenbo Sun, Hongyan Huang, Baomin Zhao, Kuan Sun and Jianyong Ouyang14.1 Introduction 45814.2 Transparent Conjugated Polymers 45914.2.1 Solvent Additive Method 46014.2.2 Post-Treatment of PEDOT:PSS Films 46114.2.3 Printing PEDOT:PSS Inks 46314.3 Carbon-Based Nanomaterials 46314.3.1 Graphene 46614.3.2 Carbon Nanotubes 47214.4 Metallic Nanostructures 47614.4.1 Metal Nanomeshes 47614.4.2 Metal Nanowire Networks 48014.4.3 Ultrathin Metal Films 48214.5 Multilayer Thin Films 48614.6 Printable Metal Back Electrodes 49114.7 Carbon-Based Back Electrodes 49414.8 Summary and Outlook 497Acknowledgment 498References 49815 Photonic Crystals for Photon Management in Solar Cells 513Shuai Zhang, Zhongze Gu and Jian-Ning Ding15.1 Introduction 51315.2 Fundamentals of PCs 51515.3 Fabrication Strategies of PCs for Photovoltaics 51815.3.1 1D Multilayer PCs 51915.3.2 2D PCs 52415.3.3 3D PCs 52715.4 Different Functionalities of PCs in Solar Cells 53015.4.1 PC Reflectors 53115.4.2 PC Absorbers 53515.4.3 Front-Side PCs 53815.4.4 PCs for Other Functionalities 54015.5 Summary and Outlook 540Acknowledgment 542References 542