Nano-Structured Photovoltaics Solar Cells in the Nanotechnology Era

Cover
Half Title
Title
Copyright
Dedication
Contents
Preface
Acknowledgments
About the Author
About the Book
Acronyms and Abbreviations
Chemical Symbols
Mathematical Symbols
Part I Preliminaries and Nanocrystalline Silicon Photovoltaics
Chapter 1 Solar Cell Basics
1.1 Progression from Fossil Fuels to Renewable Energy Sources
1.1.1 Fossil Fuels, the Lifeblood of Modern Civilization
1.1.2 Evils and Limitations of Fossil Fuels
1.1.2.1 Land and Habitat Destruction
1.1.2.2 Greenhouse Effect
1.1.2.3 Global Warming
1.1.2.4 Depletion of Fossil Fuels
1.1.3 Promises of Solar Energy for Sustainable Development
1.2 Solar Power Generating System
1.2.1 Photovoltaic Power System
1.2.2 Concentrated Power System
1.3 Photovoltaic Power System
1.3.1 Off-Grid (Stand-Alone or Grid Fallback) Solar Power System
1.3.2 Grid-Tie Solar Power System
1.4 Construction and Working of a Solar Cell
1.5 Optoelectrical Characteristics and Parameters of a Solar Cell
1.5.1 Short-Circuit Current (ISC)
1.5.2 Open-Circuit Voltage (VOC)
1.5.3 Maximum Power (PM) and Maximum Power Point (PMPP)
1.5.4 Fill Factor
1.5.5 Power Conversion Efficiency
1.5.6 AM0 and AM1.5 Solar Spectra
1.5.7 Shockley-Queisser Detailed Balance Limit of Efficiency of P-N Junction Solar Cell
1.6 Solar Cell Generations
1.6.1 First Generation
1.6.2 Second Generation
1.6.3 Third Generation
1.7 Solar Cell Technologies
1.7.1 Monocrystalline Silicon Solar Cell
1.7.2 Gallium Arsenide Solar Cell
1.7.3 Amorphous Silicon Solar Cell
1.7.4 Silicon Heterojunction Solar Cell
1.7.5 Cadmium Telluride Solar Cell
1.7.6 Cadmium Indium Gallium Selenide (CIGSe) Solar Cell
1.7.7 Perovskite Solar Cell
1.7.8 Organic Solar Cell
1.7.9 Hybrid Solar Cell
1.7.10 Dye-Sensitized Solar Cell
1.8 Discussion and Conclusions
References
Chapter 2 Nanotechnology Fundamentals
2.1 Nanotechnology
2.2 Nanomaterials
2.3 0D Nanomaterials
2.3.1 Nanoparticle
2.3.2 Buckminsterfullerene (C60)
2.3.3 Quantum Dot
2.4 1D Nanomaterials
2.4.1 Nanowire
2.4.2 Carbon Nanotube
2.5 2D Nanomaterials
2.5.1 Graphene
2.5.2 2D Perovskites
2.5.3 Quantum Well
2.6 Scope for Nanotechnology Application in Solar Cells and Organizational Structure of the Book
2.6.1 Use of Nanocrystalline Silicon in Solar Cells
2.6.2 Nanotexturing Solar Cell Surface
2.6.3 Using Plasmonic Nanostructures for Maximizing Light Coupling in Solar Cells
2.6.4 Further Approaches to Light Incoupling in Solar Cells
2.6.5 Sensitizing Metal Oxide Semiconductor (TiO2) Nanoparticles with Dye
2.6.6 Promises of 2D Perovskites Nanomaterials
2.6.7 Applications of Carbon Nanostructures
2.6.8 Applications of Nanowires
2.6.9 Applications of Quantum Wells
2.6.10 Applications of Quantum Dots
2.7 Discussion and Conclusions
References
Chapter 3 Nanocrystalline Silicon-Based Solar Cells
3.1 Nanocrystalline, Polycrystalline, and Amorphous Silicon Phases as Photovoltaic Cell Materials
3.1.1 Nanocrystalline Silicon
3.1.2 Nanocrystalline vs. Polysilicon
3.1.3 Amorphous Silicon
3.1.4 Advantages of Nanocrystalline Silicon over Amorphous and Polysilicon
3.2 Plasma-Enhanced Chemical Vapor Deposition of a-Si:H and nc-Si:H Films
3.2.1 Effect of Hydrogen Dilution
3.2.2 High-Pressure Depletion (HPD) Regime
3.3 Silicon Heterojunction (SHJ) Solar Cell
3.3.1 Fabrication of the Solar Cell
3.3.2 Process Sequence
3.3.3 Back Surface Field (BSF)
3.4 Front- and Rear-Emitter Silicon Heterojunction Solar Cell
3.4.1 Front-Emitter Solar Cell
3.4.2 Rear-Emitter Solar Cell
3.4.3 Advantages of Rear-Emitter Design
3.5 Replacement of Amorphous Silicon by Nanocrystalline Silicon as Electron/Hole Collectors
3.5.1 Reasons for Replacement
3.5.2 Effects of Replacement
3.6 Nanocrystalline N-Type Silicon Oxide Films as Front Contacts in Rear-Emitter Solar Cells
3.6.1 Effect of Refractive Index Matching of Two Optical Media upon Reflection of Light at Their Interface
3.6.2 Comparing Reflectances at the Interfaces a-Si:H/TCO, nc-Si:H/TCO, and nc-SiO2:H/TCO
3.6.3 Difficulty in Deposition of Thin nc-SiO2:H Film Over (I)a-Si:H Layer
3.7 Nanocrystalline Silicon Thin-Film Solar Cell on Honeycomb-Textured Substrate
3.8 Discussion and Conclusions
References
Part II Nanotechnological Approaches to Sunlight Harvesting
Chapter 4 Nanotextured-Surface Solar Cells
4.1 Optical Losses in a Solar Cell and Loss-Reduction Approaches
4.1.1 Optical Losses
4.1.2 Optical Loss Reduction by Optical Transmittance Enhancement
4.1.3 Optical Loss Reduction by Optical Path Lengthening
4.2 Optical Transmittance Enhancement by Nanotexturing
4.2.1 Reflectance and Transmittance Equations
4.2.2 Effects of Sizes of Structures of the Textured Interface Morphology on its Reflectance
4.3 Nanotextured Surface Properties, Examples in Nature, and Comparison with Microtexturing
4.3.1 Self-Cleaning Property of Nanotextured Surfaces
4.3.2 Moth-Eye Nanostructured Surfaces
4.3.3 Nanotexturing vs. Microtexturing
4.4 Nanotextured Silicon Solar Cell Fabrication
4.4.1 Inverted Nanopyramid Crystalline Silicon Solar Cell by a Maskless Technique (η = 7.12%)
4.4.2 Ultrathin (Sub-10μm) Silicon Solar Cell with Silicon Nanocones and All Contacts on the Backside (η = 13.7%)
4.4.2.1 Carrier Recombination Problems Faced in a Front-Emitter Solar Cell
4.4.2.2 Solving the Recombination Problem
4.4.2.3 Fabrication of the Solar Cell
4.4.2.4 Planar Cell and Nanocone Cell Parameters
4.4.3 10-μm-Thick Periodic Nanostructured Crystalline Silicon Solar Cell (η = 15.7%)
4.4.4 Two-Scale (Micro/Nano) Surface Textured Crystalline Silicon Solar Cell (η = 17.5%)
4.5 Nanotextured Solution-Processed Perovskite Solar Cell (η = 19.7%)
4.6 Discussion and Conclusions
References
Chapter 5 Plasmonic-Enhanced Solar Cells
5.1 Plasma, Plasmon, and Plasmonics
5.1.1 Plasma
5.1.2 Plasmon
5.1.3 Plasmonics
5.2 Surface Plasmons, Localized Surface Plasmons, and Surface Plasmon Polaritons
5.2.1 Surface Plasmons
5.2.2 Localized Surface Plasmons
5.2.3 Surface Plasmon Polaritons
5.2.4 Localized Surface Plasmon Resonance (LSPR) and Propagating Surface Plasmon Resonance (PSPR)
5.2.4.1 Localized SPR
5.2.4.2 Propagating SPR
5.3 Absorption and Scattering of Light
5.3.1 Absorption of Light
5.3.2 Scattering of Light
5.3.3 Absorption and Scattering Cross Sections of a Particle
5.4 Surface Plasmon Effects in Solar Cells
5.4.1 LSPR with Metal Nanoparticles
5.4.1.1 Device Structures Used
5.4.1.2 Resonance Frequency Formula for LSPR
5.4.1.3 Red Shifting of Resonance Frequency by Embedded Metal Nanoparticles
5.4.1.4 Intensification of Local Electric Field of Light at Resonance
5.4.1.5 Enhancement of Scattering of Light at Resonance
5.4.2 PSPR at Metal-Semiconductor Interface
5.4.2.1 Necessity of Coupling Medium for Exciting Surface Plasmon Polaritons
5.4.2.2 Approaches for Matching Momenta
5.5 Plasmonic-Enhanced GaAs Solar Cell Decorated with Ag Nanoparticles (η = 5.9%)
5.6 Plasmonic-Enhanced Organic Solar Cells
5.6.1 LSPR Effect of Gold Nanospheres in the Buffer Layer (η = 2.36%)
5.6.2 Combined Surface Plasmon Effects from Ag Nanodisks in Hole Transport Layer and 1D-Imprinted Al Grating of a Bulk Heterojunction Solar Cell (η = 3.59%)
5.6.3 Multiple Effects of Au Nanoparticles Embedded in the Buffer Layer of Inverted Bulk Heterojunction Solar Cell (η = 7.86%)
5.7 Plasmonic-Enhanced Perovskite Solar Cells
5.7.1 Reduced Exciton Binding Energy Effect in Perovskite Solar Cell with Core-Shell Metal Nanoparticles (η = 11.4%)
5.7.2 LSPR Effect of Gold Nanorods in the Electron Transport Layer of Inverted Perovskite Solar Cell (η = 13.7%)
5.8 Discussion and Conclusions
References
Chapter 6 Optically Improved Nanoengineered Solar Cells
6.1 Introspection on Light Management in Solar Cells
6.1.1 Antireflection Coating
6.1.2 Micropyramid-Like Texturing by Wet-Etching in Alkaline Solutions
6.1.3 Nanopyramid-like Texturing by Lithographical Techniques
6.1.4 Plasmonic Effects of Metal Nanoparticles or Thin Films
6.1.5 Other Ways of Light Trapping
6.2 Ultrathin GaAs Absorber (205nm) Solar Cell with TiO2/Ag Nanostructured Back Mirror
6.2.1 Justification for Thinning of the Absorber Layer Together with Advanced Light Loss Reduction Technique
6.2.2 Multiresonant Absorption of Light
6.2.3 Location and Geometrical Parameters of the Nanostructured Mirror
6.2.4 Fabrication and Performance of the Solar Cell
6.3 Ultrathin CIGSe Absorber (460 nm) Solar Cell with Dielectric Nanoparticles
6.3.1 Structure of the Solar Cell
6.3.2 Drawbacks of Plasmonic Metal Nanoparticles
6.3.3 Scattering Properties of Dielectric Nanoparticles
6.3.4 Fabrication of the Solar Cell with Silica Dielectric Nanoparticles at the Rear Surface
6.3.5 Solar Cell with Silica Nanoparticles vs. Flat Solar Cell without Silica Nanoparticles
6.3.6 Solar Cell with TiO2 Nanoparticles on the Front Surface
6.4 Periodic Nanohole Array Solar Cell
6.4.1 Positive and Negative Textures
6.4.2 Nanowires and Nanopores
6.4.3 Fabrication of Nanohole Array Solar Cell
6.5 Random Nanohole Array Solar Cell
6.5.1 Fabrication of Random Nanohole Array
6.5.2 Fabrication and Parameters of Solar Cell
6.6 Silicon Nanohole/Organic Semiconductor Heterojunction Hybrid Solar Cell
6.6.1 Fabrication of Hybrid Solar Cell
6.6.2 Parameters of the Solar Cell
6.7 Discussion and Conclusions
References
Part III Electrochemical Photovoltaics Using Nanomaterials
Chapter 7 Dye-Sensitized Solar Cells
7.1 Construction and Working Principle of a Dye-Sensitized Solar Cell (DSSC)
7.1.1 The Nanoconstituent of the Cell
7.1.2 Cell Construction
7.1.3 Cell Principle
7.1.4 Mimicking the Natural Photosynthesis Process
7.2 DSSC Components
7.2.1 Transparent Conductive Substrate
7.2.2 Nanostructured Semiconductor Working Electrode (Photoanode)
7.2.3 Dye (Photosensitizer)
7.2.3.1 Naturally Occurring Dyes
7.2.3.2 Metal Complex Sensitizers
7.2.3.3 Metal-Free Organic Dyes
7.2.4 Electrolyte
7.2.4.1 Tasks Performed by the Electrolyte
7.2.4.2 Essential Properties of the Electrolyte
7.2.4.3 Liquid Electrolytes
7.2.4.4 Solid and Quasisolid Electrolytes
7.2.5 Counter Electrode (CE)
7.3 Forward and Backward Electron Transfer Processes in DSSC
7.3.1 Forward Electron Transfer Processes
7.3.1.1 Receipt and Absorption of Sunlight by the Dye and Promotion of an Electron in the Dye from Its HOMO to the LUMO (Ground State to Excited State)
7.3.1.2 Injection of an Electron from the LUMO of the Dye to the Conduction Band of the Semiconductor (TiO2): Charge Separation
7.3.1.3 Diffusion of the Electron through the TiO2 Nanonetwork to Reach the TCO Layer
7.3.1.4 Flow of the Electron through the External Circuit Reaching the Counter Electrode
7.3.1.5 Reduction of I3– Ion in the Electrolyte to I– Ion by the Arriving Electron at the Counter Electrode
7.3.1.6 Acceptance of an Electron by the Dye From the I– Ion in the Electrolyte, Restoring It to Its Original State
7.3.1.7 Diffusion of I3– Ion Mediator towards the Counter Electrode and Its Reduction to I– Ion by Receiving an Electron from the External Circuit Recovering Its Initial State
7.3.2 Backward Electron Transfer Processes: Loss Mechanisms
7.4 Effect of Doping the TiO2 Photoanode Film with Gold Nanoparticles on DSSC Performance
7.4.1 Synthesis of Au Nanoparticles
7.4.2 TiO2 Film Deposition
7.4.3 Sensitization of TiO2 Film with Dye
7.4.4 Counter Electrode Fitting and Assembly of the Solar Cell
7.4.5 Characterization of Solar Cell
7.4.6 Dependence of Solar Cell Efficiency on Nanoparticle Dimensions and Shape
7.5 Effect of Inclusion of Broadband Near-Infrared Upconversion Nanoparticles (UCNPs) in the TiO2 Photoanode of DSSC on Its Power Conversion Efficiency
7.5.1 How Upconversion Nanoparticles Assist in Utilization of Low-Energy Photons?
7.5.2 Preparation of Upconversion Nanoparticles
7.5.3 Preparation of IR783 Dye-Sensitized Upconversion Nanoparticles
7.5.4 Reason for Sensitizing the Upconversion Nanoparticles with IR783 Dye
7.5.5 Making the N719 Dye-Sensitized TiO2 Photoanode
7.5.6 Deposition of IR783 DSUNPs on N719 Dye-Sensitized TiO2 Photoanode
7.5.7 Making the Counter Electrode of Platinized FTO Glass
7.5.8 Sealing the IR783 DSUNPs@N719 Dye-Sensitized TiO2 Photoanode with Counter Electrode
7.5.9 DSUCNPs-Sensitized DSSC Testing
7.6 Discussion and Conclusions
References
Part IV Photovoltaics with 2D Perovskites and Carbon Nanomaterials
Chapter 8 2D Perovskite and 2D/3D Multidimensional Perovskite Solar Cells
8.1 The 3D Perovskite
8.1.1 Favorable Properties of 3D Perovskites for Solar Cell Fabrication
8.1.2 Shortcomings of 3D Perovskites for Use in Solar Cells
8.2 The 2D Perovskite
8.2.1 What Happens When the A-Site Cation Is Large in Size?
8.2.2 2D Perovskites as a Promising Option
8.2.3 Inferior Aspects of 2D Perovskites to 3D Perovskites
8.2.4 The Two Routes to Success
8.3 2D Perovskite Solar Cells
8.3.1 PbBr2-Incorporated 2D Perovskite Solar Cell (η = 12.19%)
8.3.2 2D GA2MA4Pb5I16 Perovskite Solar Cell Interface Engineered with GABr (η = 19.3%)
8.3.3 FA-Based 2D Perovskite Solar Cell (η = 21.07%)
8.4 2D/3D Perovskite Solar Cells
8.4.1 2D/3D (HOOC(CH2)4NH3)2PbI4/CH3NH3PbI3 Perovskite Interface Engineered Solar Cell (η = 14.6%)
8.4.2 2D Perovskite-Encapsulated 3D Perovskite Solar Cell (η = 16.79%)
8.4.3 Hole Transport Material–Free Perovskite Solar Cell Using 2D Perovskite as an Electron Blocking Layer Over 3D Perovskite Light-Absorbing Layer (η = 18.5%)
8.4.4 Polycrystalline FAPbI3 3D Perovskite Solar Cell with 2D PEA2PbI4 Perovskite at Grain Boundaries (η = 19.77%)
8.5 Discussion and Conclusions
References
Chapter 9 Carbonaceous Nanomaterials–Based Solar Cells
9.1 Using Carbon Nanotubes to Make an Inexpensive Counter Electrode for a Dye-Sensitized Solar Cell
9.1.1 Replacing Platinum with CNTs-Coated Nonconductive Glass Plate
9.1.2 Replacing Platinum with Pt NPs/CNTs Nanohybrid-Coated Nonconductive Glass Plate
9.1.3 Performance of CNTs and Pt NPs/CNTs Electrodes in a Solar Cell
9.1.4 Pt NPs/CNTs Nanohybrid
9.1.5 CNTs and Pt NPs/CNTs Dispersants
9.1.6 CNTs and Pt NPs/CNTs Electrodes
9.1.7 Dye-Sensitized Solar Cells with CNTs and Pt NPs/CNTs Electrodes
9.1.8 Parameters of Solar Cells with CNTs and Pt NPs/CNTs Electrodes
9.2 Using Carbon Nanotubes to Improve the Properties of TiO2-Based Electron Transport Material in Perovskite Solar Cells
9.2.1 Advantages and Limitations of TiO2 as an Electron Transport Material
9.2.2 Choice of CNTs as TiO2 Conductivity-Enhancement Nanomaterials
9.2.3 Fabrication of the Solar Cell Using TiO2 NPs-SWCNTs Nanocomposite
9.2.4 Solar Cell with TiO2 NPs-SWCNTs and Control Cell
9.3 Using CNTs and C60 to Make a High-Stability, Cost-Effective Perovskite Solar Cell
9.3.1 Material Replacements in Traditional Structure
9.3.2 Fabrication of Perovskite Solar Cell with Replaced Materials
9.3.3 Solar Cell Performance vs. Cost
9.4 Integrating CNTs in a Silicon-Based Solar Cell: Si-CNTs Hybrid Solar Cell
9.4.1 Advantages of CNTs Integration
9.4.2 Fabrication of the Solar Cell
9.4.3 Testing of the Solar Cell
9.5 Si-CNTs Hybrid Solar Cell Fabrication by Superacid Sliding Coating
9.5.1 Superacid Slide Casting Method for High-Quality CNTs Film Preparation
9.5.2 Process Sequence
9.6 TiO2-Coated CNTs-Si Solar Cell
9.7 Using Graphene to Make Semitransparent Perovskite Solar Cells
9.7.1 Semitransparent Solar Cells and Suitability of Graphene for These Cells
9.7.2 Parts of Semitransparent Solar Cell
9.7.2.1 Making Part I
9.7.2.2 Making Part II
9.7.2.3 Assembling Together Parts I and II
9.7.2.4 Multilayer Graphene and Gold Electrode Solar Cells
9.8 Graphene/N-Type Si Schottky Diode Solar Cell
9.8.1 Doping Graphene with TFSA
9.8.2 Fabrication of Graphene/N-Si Solar Cell
9.8.3 Parameters of Solar Cell with and without Doping with TFSA
9.9 Discussion and Conclusions
References
Part V Quantum Well, Nanowire, and Quantum Dot Photovoltaics
Chapter 10 Quantum Well Solar Cells: Particle-in-a-Box Model and Bandgap Engineering
10.1 What is a Quantum Well Solar Cell?
10.1.1 QW Solar Cell as a Way of Extending the Useful Range of Solar Spectrum Utilized for Energy Conversion
10.1.2 QW Solar Cell as an Approach towards Realizing Multijunction Solar Cells with Optimal Bandgaps
10.2 The QW Structure
10.3 Physics of Quantum Wells
10.3.1 Particle-in-a-Box Model of the Quantum Well
10.3.2 Imagining Quantum Well as a Finite Potential Well
10.3.3 Energy States of a Quantum Well and Defining an Effective Bandgap of the Quantum Well
10.3.4 Difference between the Multiple–Quantum Well and Superlattice Structures
10.3.5 Charge Transport Mechanisms in the Quantum Well Solar Cell
10.3.6 Excitonic Model of Optical Absorption
10.4 Bandgap Engineering of Quantum Well Architectures
10.5 Inclusion of Strain and Electric Field Effects for Generalization of Energy Gap Variation Equation
10.6 Discussion and Conclusions
References
Chapter 11 Quantum Well Solar Cells: Material Systems and Fabrication
11.1 Techniques for Growth of Quantum Well Structures
11.1.1 Molecular Beam Epitaxy
11.1.2 Metal-Organic Chemical Vapor Deposition
11.1.3 Difference between MBE and MOCVD
11.2 Materials Systems and Structures for Quantum Well Solar Cells
11.2.1 Lattice-Matched Quantum Well Solar Cells
11.2.2 Strain-Balanced Quantum Well Solar Cells
11.2.3 Strained Quantum Well Solar Cells
11.3 Inverted GaAs Solar Cell with Strain-Balanced GaInAs/GaAsP Quantum Wells (η = 27.2%)
11.4 GaInP/GaAs Dual-Junction Solar Cell with Strain-Balanced GaInAs/GaAsP Quantum Wells in the Bottom Cell (η = 32.9%)
11.5 Triple-Junction Solar Cell with GaInAs/GaAsP Quantum Wells in the Middle Cell (η = 39.5%)
11.6 Discussion and Conclusions
References
Chapter 12 Nanowire Solar Cells: Configurations
12.1 Reasons for Interest in Nanowire Solar Cells
12.2 Broad Classification of Nanowire Solar Cells
12.2.1 Two Types of Solar Cells According to the Number of Nanowires
12.2.2 Two Types of Solar Cells According to Direction of Charge Separation
12.2.3 Radial vs. Axial Junction Solar Cell
12.3 Nanowire Solar Cell Properties and Operation through Examples
12.4 Discussion and Conclusions
References
Chapter 13 Nanowire Solar Cells: Fabrication
13.1 Single-Nanowire Solar Cells
13.1.1 Single GaAs Nanowire Solar Cell in Vertical Configuration (η = 40%)
13.1.1.1 Fabrication Plan Outline
13.1.1.2 Preparation of Oxidized P+ Silicon (100) Substrate with Apertures of 50–70nm Size
13.1.1.3 Ga-Assisted VLS Growth of P-type GaAs Nanowire Core
13.1.1.4 Growth of P+-type GaAs Nanowire Shell
13.1.1.5 Growth of an Undoped and N-type GaAs Nanowire Shell
13.1.1.6 Making Electrical Contacts with the Nanowire
13.1.1.7 Solar Cell Parameters
13.1.2 Surface-Passivated Single GaAsP Nanowire Solar Cell in Horizontal Configuration (η = 10.2%)
13.1.2.1 Fabrication Plan Outline
13.1.2.2 Growth of P-I-N Radial Junction Core-Shell GaAs0.8P0.2 Nanowires
13.1.2.3 Surface Passivation
13.1.2.4 Nanowire Removal from Growth Substrate and Alignment on P+ Substrate
13.1.2.5 P-Contact to the Nanowire
13.1.2.6 N-Contact to the Nanowire
13.1.2.7 Contact Pads
13.1.2.8 Solar Cell Parameters
13.2 GaAs Nanowire-on-Si Tandem Solar Cell (η = 11.4%)
13.3 GaAs Nanowire Array Solar Cell (η = 15.3%)
13.3.1 Making Au Disk Pattern
13.3.2 VLS Method of Nanowire Growth
13.3.3 P- and N-Type Doping
13.3.4 Passivation
13.3.5 Nanowire Diameter, Length, and Segments
13.3.6 SiO2 Deposition and Surface Planarization
13.3.7 Electrical Contacts
13.3.8 GaAs Cell Parameters
13.4 InP Nanowire Array Solar Cell Fabrication by Bottom-Up Approaches
13.4.1 Solar Cell (η = 11.1%) with InP Nanowires Grown via Vapor-Liquid-Solid Mechanism and Surface Cleaning
13.4.1.1 Nanowire Growth, Doping, and Passivation
13.4.1.2 Top and Bottom Contacts
13.4.1.3 Solar Cell Parameters
13.4.1.4 Role of Nanowire Surface Cleaning
13.4.2 Solar Cell (η = 13.8%) with Epitaxially Grown InP Nanowires
13.4.2.1 InP Nanowire Growth and Covering Its Sidewalls with SiO2
13.4.2.2 Making Contacts
13.4.2.3 Solar Cell Parameters
13.5 InP Nanowire Array Solar Cell (η = 17.8%) Fabrication by Top-Down Approach: Dry-Etching from Epitaxially Grown Stack
13.5.1 Epitaxy
13.5.2 Lithography
13.5.3 Dry-Etching
13.5.4 Nanowire Dimensions
13.5.5 SiO2 Deposition and BCB Filling
13.5.6 Top Electrode
13.5.7 ITO Spreading and Rearrangement by Self-Alignment over the InP and BCB
13.5.8 Role of Nanostructured ITO
13.5.9 Bottom Electrode
13.5.10 Gold Border Film
13.5.11 InP Cell Parameters
13.6 Wet-Etching Processes of Silicon Nanowire Array Solar Cell Fabrication
13.6.1 Radial Junction Solar Cell (η = 13.7%) Fabrication on P-type Wafers with Si NWs Made by Wet-Etching
13.6.1.1 Fabrication Plan Outline
13.6.1.2 Metal-Assisted Chemical Etching (MACE or MacEtch) of Silicon
13.6.1.3 Nanowire Diameter and Areal Density
13.6.1.4 Removal of Ag Residues
13.6.1.5 Formation of N-Type Shell Layer
13.6.1.6 Metallization
13.6.1.7 Solar Cell Testing
13.6.2 Solar Cell (η = 17.11%) with Dielectric Passivation of Si Nanowires
13.6.2.1 Fabrication Plan Outline
13.6.2.2 Nanowire Creation by Etching P-type Si Wafer, N-Type Shell Formation, and Surface Passivation
13.6.2.3 Optical Reflectance, Carrier Recombination Properties, and Efficiency
13.6.3 Solar Cell (η = 13.4%) Fabrication on N-Type Si Wafers
13.6.3.1 Nanowire Formation
13.6.3.2 Nanowire Doping
13.6.3.3 Contacts
13.6.3.4 Comparison of Two Geometrical Designs
13.6.3.5 Reflectance Dependence on Nanowire Length
13.7 Dry-Etching Process of Silicon Nanowire Array Solar Cell (η = 11.7%) Fabrication
13.7.1 SiO2 Hard Mask Creation for Silicon Etching
13.7.2 Silicon Etching
13.7.3 Photoresist and Oxide Removal
13.7.4 N-Type Layer Formation by Ion Implantation
13.7.5 Dopant Activation
13.7.6 Nanowire Surface Passivation
13.7.7 Backside Contact
13.7.8 Top Contact
13.7.9 Photovoltaic Properties of the Cell
13.8 Discussion and Conclusions
References
Chapter 14 Quantum Dot Solar Cells: Bandgap and Multicarrier Effects
14.1 Bandgap Tuning of Quantum Dots
14.1.1 Quantum Dots as a Particle-in-a-Box System
14.1.2 Effective Bandgap of the Quantum Dot
14.2 Multiple Exciton Generation (MEG)
14.2.1 Difference between Bulk Solar Cell and Quantum Dot Solar Cell
14.2.2 Reason for Greater Likelihood of MEG in a Quantum Dot
14.2.3 Corresponding Terms for a Bulk Semiconductor and a Quantum Dot
14.3 Drawing Energy Band Diagrams of Heterojunctions
14.3.1 Rules and Considerations in the Construction of Energy Band Diagrams of Heterojunctions
14.3.2 Driving Energy for Charge Transfer across a Heterojunction
14.4 Discussion and Conclusions
References
Chapter 15 Quantum Dot Solar Cells: Types of Cells and Their Fabrication
15.1 Classification of Quantum Dot Solar Cells
15.2 Quantum Dot P-N Junction Solar Cells
15.2.1 PbS QD Solar Cell with NaHS-Treated P-Type Layer (η = 7.6%)
15.2.1.1 Substrate
15.2.1.2 Oleic Acid–Capped PbS QD Synthesis
15.2.1.3 Anatase TiO2 Deposition
15.2.1.4 N-Type PbS Film (PbS QDs Treated with TBAI) Deposition
15.2.1.5 P-Type PbS Film (PbS QDs Capped with EDT) Deposition
15.2.1.6 MoO3 (5nM) and Au (80nm) Deposition
15.2.1.7 Enhancement of Power Conversion Efficiency by Increase in P-Type Doping with NaHS Treatment
15.2.2 Improved Reliability PbS QD Solar Cell with Atomic-Layer Deposited TiO2 Electron Transport Layer (η = 5.5–7.2%)
15.2.3 Low-Cost PbS QD Solar Cell with ZnO Electron Transport Layer and Stable Cr-Ag Electrodes (η = 6.5%)
15.2.4 PbS QD Solar Cell by a Scalable Industrially Suited Doctor Blading Process Using N- and P-Type Inks (η = 9%)
15.2.5 PbS QD Solar Cell with PD2FCT-29DPP as HTL (η = 14%)
15.2.6 PbS QD Solar Cell (η = 10.06%) as the Back Cell in a Tandem Solar Cell (η = 18.9%)
15.2.6.1 Front Semitransparent Perovskite Solar Cell
15.2.6.2 Back Colloidal Quantum Dot Solar Cell
15.2.6.3 Stacking the Cells for Proper Light Coupling
15.2.7 PbS QD Solar Cell (η = 11.6%) as the Back Cell in a Tandem Solar Cell (η = 20.2%)
15.3 Quantum Dot Schottky Barrier Solar Cell (η = 1.8%)
15.3.1 Synthesis of PbS QD Film and Ligand Exchange for Improving Conductivity
15.3.2 PbS QD Film Deposition and Making Contacts
15.3.3 Operation
15.3.4 Solar Cell Performance Parameters
15.3.5 Shortcomings of Schottky Diode Quantum Dot Solar Cells
15.4 Quantum Dot–Depleted Heterojunction Solar Cell (η = 3.36%)
15.4.1 TiO2 Nanoparticle Film
15.4.2 PbS QD Synthesis
15.4.3 Layer-by-Layer Deposition of PbS QD Film on Porous TiO2 Film
15.4.4 Top Electrode Deposition
15.4.5 Measurements
15.4.6 Working of the Cell
15.4.7 Surmounting the Drawbacks of Schottky Diode Cell
15.5 Quantum Dot–Depleted Bulk Heterojunction Solar Cell (η = 5.5%)
15.5.1 Disadvantages of Schottky Diode and Depleted Heterojunction Structures and Evolving Improved Designs
15.5.2 Difference between Fabrication Processes of DH and DBH Solar Cells
15.6 Quantum Dot Hybrid Solar Cell (η = 4.91%)
15.6.1 Necessity of Hybrid QD Solar Cell
15.6.2 Hybrid QD Solar Cell Structure
15.6.3 P3HT-Br Synthesis
15.6.4 Formation of P3HT-b-PS
15.6.5 PbS QD Synthesis
15.6.6 Substrate Cleaning
15.6.7 PEDOT:PSS Coating
15.6.8 P3HT-b-PS/PbS QDs Coating
15.6.9 Post-Ligand Exchange to BDT
15.6.10 Pure Layer of PbS QDs with Oleic Acid Ligands
15.6.11 Cathode Deposition
15.6.12 Solar Cell Testing
15.7 Quantum Dot–Sensitized Solar Cell
15.7.1 Similarities and Dissimilarities with DBH Solar Cell
15.7.2 Difference from Dye-Sensitized Solar Cell
15.7.3 Construction
15.7.4 Principle
15.8 Fabrication of PbS QD-Sensitized Solar Cells
15.8.1 PbS-ZnS QDs-Sensitized Solar Cells (η = 2.41, 4.01%)
15.8.1.1 Mesoporous TiO2 Film Deposition on FTO Substrate
15.8.1.2 Deposition of PbS QDs on TiO2 Layer
15.8.1.3 Deposition of ZnS Passivation Layer
15.8.1.4 Electrolyte
15.8.1.5 Deposition of Cu2S Film on Brass Foil to Make the Counter Electrode
15.8.1.6 Photovoltaic Characterization of the Solar Cell
15.8.2 PbS-ZnS QDSSC (η = 5.82%)
15.8.2.1 Compact TiO2 layer
15.8.2.2 Porous TiO2 Layer
15.8.2.3 Sensitization of Porous TiO2 Layer with PbS QDs
15.8.2.4 Passivation of QDs with ZnS, Electrolyte Injection, and Device Assembly
15.9 Fabrication of CdS QD-Sensitized Solar Cells
15.9.1 CdS QDSSC with η = 1.84%
15.9.1.1 CdS QDs-Modified TiO2 Electrode
15.9.1.2 Counter Electrode
15.9.1.3 Redox Electrolyte
15.9.1.4 Sealing
15.9.1.5 Efficiency
15.9.2 CdS QDSSC Using Graphene Oxide Powder (η = 2.02%)
15.9.3 Increasing the QDSSC Efficiency by Modification of CdS with 2D g-C3N4 (η = 2.31%)
15.9.4 Raising the QDSSC Efficiency by Mn-Doping of CdS (η = 3.29%)
15.9.5 GO/N-Doped TiO2/CdS/Mn-Doped ZnS/Zn-Porphyrin QDSSC (η = 4.62%)
15.9.6 Mixed-Joint CdS-ZnS QDSSC (η = 6.37%) and ZnS QDSSC (η = 2.72%)
15.10 Quantum Dot Intermediate Band Solar Cell (η = 16.3%)
15.10.1 Intermediate Band Solar Cell Concept and Energy Band Diagram
15.10.2 Quantum Engineering
15.10.3 Growth of Quantum Dots
15.10.4 Device Structure
15.10.5 Signature of Intermediate Band
15.10.6 Photovoltaic Parameters of the QD-IBSC
15.11 Discussion and Conclusions
References
Index A: Solar cells
Index B: General