Atomic Layer Deposition in Energy Conversion Applications

Combining the two topics for the first time, this book begins with an introduction to the recent challenges in energy conversion devices from a materials preparation perspective and how they can be overcome by using atomic layer deposition (ALD). By bridging these subjects it helps ALD specialists to understand the requirements within the energy conversion field, and researchers in energy conversion to become acquainted with the opportunities offered by ALD. With its main focus on applications of ALD for photovoltaics, electrochemical energy storage, and photo- and electrochemical devices, this is important reading for materials scientists, surface chemists, electrochemists, electrotechnicians, physicists, and those working in the semiconductor industry.

Table of Contents:
Preface xi Julien Bachmann The Past of Energy Conversion xi The Future of Energy Conversion xi Technical Ingredients Needed xiii Scope of This Book xiv Photovoltaics: Strategies, Length Scales, and ALD xv Electrochemical Energy Storage: Principles, Chemistries, and ALD xvii Other Energy Conversion Strategies Based on Interfaces xix References xx List of Contributors xxiii Part I Introduction to Atomic Layer Deposition 1 1 Basics of Atomic Layer Deposition: Growth Characteristics and Conformality 3 Jolien Dendooven and Christophe Detavernier 1.1 Atomic Layer Deposition 3 1.1.1 Principle of ALD 3 1.1.2 ALD Growth Characteristics – Linearity, Saturation, and ALD Window 5 1.1.3 Plasma-Enhanced ALD 8 1.2 In Situ Characterization for Studying ALD Processes 11 1.2.1 Quartz Crystal Microbalance 12 1.2.2 Quadrupole Mass Spectrometry (QMS) 13 1.2.3 Spectroscopic Ellipsometry 14 1.2.4 Fourier Transform Infrared Spectroscopy 15 1.2.5 Optical Emission Spectroscopy 15 1.2.6 Other In Situ Techniques 16 1.3 Conformality of ALD Processes 16 1.3.1 Quantifying the Conformality of ALD Processes 17 1.3.2 Modeling the Conformality of ALD 21 1.3.3 The Conformality of Plasma-Enhanced ALD 24 1.3.4 Conformal Coating of Nanoporous Materials 29 References 34 Part II Atomic Layer Deposition in Photovoltaic Devices 41 2 Atomic Layer Deposition for High-Efficiency Crystalline Silicon Solar Cells 43 Bart Macco, Bas W. H. van de Loo, and Wilhelmus M. M. Kessels 2.1 Introduction to High-Efficiency Crystalline Silicon Solar Cells 43 2.1.1 ALD for Si Homojunction Solar Cells 44 2.1.2 ALD for Si Heterojunction Solar Cells 46 2.1.3 Novel Passivating Contacts and ALD 47 2.1.4 Outline of this Chapter 47 2.2 Nanolayers for Surface Passivation of Si Homojunction Solar Cells 48 2.2.1 Basics of Surface Passivation 48 2.2.2 Surface Passivation by ALD Al2O3 54 2.2.3 ALD in Solar Cell Manufacturing 59 2.2.4 New Developments for ALD Passivation Schemes 63 2.3 Transparent Conductive Oxides for Si Heterojunction Solar Cells 68 2.3.1 Basics of TCOs in SHJ Solar Cells 69 2.3.2 ALD of Transparent Conductive Oxides 74 2.3.3 High-Volume Manufacturing of ALD TCOs 79 2.4 Prospects for ALD in Passivating Contacts 80 2.4.1 Basics of Passivating Contacts 80 2.4.2 ALD for Passivating Contacts 86 2.5 Conclusions and Outlook 89 References 90 3 ALD for Light Absorption 101 Alex Martinson 3.1 Introduction to Solar Light Absorption 101 3.2 Why ALD for Solar Light Absorbers? 104 3.2.1 Uniformity and Precision of Large-Area Coatings 104 3.2.2 Orthogonalizing Light Harvesting and Charge Extraction 105 3.2.3 Pinhole-Free Ultrathin Films, ETA Cells 107 3.2.4 Chemical Control of Stoichiometry and Doping 107 3.2.5 Low-Temperature Epitaxy 109 3.3 ALD Processes for Visible and NIR Light Absorbers 109 3.3.1 ALD Metal Oxides for Light Absorption 111 3.3.2 ALD Metal Chalcogenides for Light Absorption 111 3.3.3 Other ALD Materials for Light Absorption 115 3.4 Prospects and Future Challenges 115 References 115 4 Atomic Layer Deposition for Surface and Interface Engineering in Nanostructured Photovoltaic Devices 119 Carlos Guerra-Nuñez, Hyung Gyu Park, and Ivo Utke 4.1 Introduction 119 4.2 ALD for Improved Nanostructured Solar Cells 120 4.2.1 Compact Layer: The TCO/Metal Oxide Interface 121 4.2.2 Blocking Layer: The Metal Oxide/Absorber Interface 126 4.2.3 Surface Passivation and Absorber Stabilization: The Absorber/HTM Interface 130 4.2.4 Atomic Layer Deposition on Quantum Dots 132 4.2.5 ALD on Large-Surface-Area Current Collectors: Compact Blocking Layers 134 4.3 ALD for Photoelectrochemical Devices for Water Splitting 138 4.4 Prospects and Conclusions 142 References 143 Part III ALD toward Electrochemical Energy Storage 149 5 Atomic Layer Deposition of Electrocatalysts for Use in Fuel Cells and Electrolyzers 151 Lifeng Liu 5.1 Introduction 151 5.2 ALD of Pt-Group Metal and Alloy Electrocatalysts 153 5.2.1 ALD of Pt Electrocatalysts 154 5.2.2 ALD of Pd Electrocatalysts 168 5.2.3 ALD of Pt-Based Alloy and Core/Shell Nanoparticle Electrocatalysts 169 5.3 ALD of Transition Metal Oxide Electrocatalysts 174 5.4 Summary and Outlook 175 Acknowledgment 178 References 178 6 Atomic Layer Deposition for Thin-Film Lithium-Ion Batteries 183 Ola Nilsen, Knut B. Gandrud, Amund Ruud, and Helmer Fjellvåg 6.1 Introduction 183 6.2 Coated Powder Battery Materials by ALD 184 6.3 Li Chemistry for ALD 186 6.4 Thin-Film Batteries 187 6.5 ALD for Solid-State Electrolytes 189 6.5.1 Li2CO3 189 6.5.2 Li–La–O 189 6.5.3 LLT 189 6.5.4 Li–Al–O (LiAlO2) 190 6.5.5 LixSiyOz 191 6.5.6 Li–Al–Si–O 191 6.5.7 LiNbO3 192 6.5.8 LiTaO3 192 6.5.9 Li3PO4 192 6.5.10 Li3N 192 6.5.11 LiPON 193 6.5.12 LiF 194 6.6 ALD for Cathode Materials 194 6.6.1 V2O5 194 6.6.2 LiCoO2 195 6.6.3 MnOx/Li2Mn2O4/LiMn2O4 196 6.6.4 Subsequent Lithiation 196 6.6.5 LiFePO4 197 6.6.6 Sulfides 198 6.7 ALD for Anode Materials 198 6.8 Outlook 199 Acknowledgments 204 References 204 7 ALD-Processed Oxides for High-Temperature Fuel Cells 209 Michel Cassir, Arturo Meléndez-Ceballos, Marie-Hélène Chavanne, Dorra Dallel, and Armelle Ringuedé 7.1 Brief Description of High-Temperature Fuel Cells 209 7.1.1 Solid Oxide Fuel Cells 209 7.1.2 Molten Carbonate Fuel Cells 210 7.2 Thin Layers in SOFC and MCFC Devices 210 7.2.1 General Features 210 7.2.2 Interest of ALD 212 7.3 ALD for SOFC Materials 213 7.3.1 Electrolytes and Interfaces 213 7.3.2 Electrodes and Current Collectors 215 7.4 Coatings for MCFC Cathodes and Bipolar Plates 216 7.5 Conclusion and Emerging Topics 218 References 218 Part IV ALD in Photoelectrochemical and Thermoelectric Energy Conversion 223 8 ALD for Photoelectrochemical Water Splitting 225 Lionel Santinacci 8.1 Introduction 225 8.2 Photoelectrochemical Cell: Principle, Materials, and Improvements 227 8.2.1 Principle of the PEC 227 8.2.2 Photoelectrode Materials 228 8.2.3 Geometry of the Photoelectrodes: Micro- and Nanostructuring 230 8.2.4 Coating and Functionalization of the Photoelectrodes 233 8.3 Interest of ALD for PEC 233 8.3.1 Synthesis of Electrode Materials 234 8.3.2 Nanostructured Photoelectrodes 235 8.3.3 Catalyst Deposition 239 8.3.4 Passivation and Modification of the Junction 240 8.3.5 Photocorrosion Protection 244 8.4 Conclusion and Outlook 247 References 247 9 Atomic Layer Deposition of Thermoelectric Materials 259 Maarit Karppinen and Antti J. Karttunen 9.1 Introduction 259 9.1.1 Thermoelectric Energy Conversion and Cooling 259 9.1.2 Designing and Optimizing Thermoelectric Materials 260 9.1.3 Thin-Film Thermoelectric Devices 262 9.2 ALD Processes for Thermoelectrics 263 9.2.1 Thermoelectric Oxide Thin Films 263 9.2.2 Thermoelectric Selenide and Telluride Thin Films 266 9.3 Superlattices for Enhanced Thermoelectric Performance 266 9.4 Prospects and Future Challenges 271 References 272 Index 275

About the Author :
Julien Bachmann is Professor of Inorganic Chemistry at the Friedrich-Alexander University of Erlangen-Nurnberg in Erlangen, Germany. He obtained his chemistry diploma from the University of Lausanne, Switzerland, and a PhD in inorganic chemistry from the Massachusetts Institute of Technology in Boston, USA. After an Alexander von Humboldt postdoctoral fellowship at the Max Planck Institute of Microstructure Physics in Halle, Germany, he was hired as a Junior Professor of Applied Physics at the University of Hamburg, Germany, before joining the faculty in Erlangen.