Nano-Structured Photovoltaics: Solar Cells in the Nanotechnology Era

495 Pages·2022·35.687 MB·English

by  Vinod Kumar Khanna

Nano-Structured Photovoltaics
Presenting a comprehensive overview of a rapidly burgeoning field blending solar cell technology
with nanotechnology, the book covers topics such as solar cell basics, nanotechnology fundamentals,
nanocrystalline silicon-based solar cells, nanotextured-surface solar cells, plasmon-enhanced solar
cells, optically improved nanoengineered solar cells, dye-sensitized solar cells, 2D perovskite and
2D/3D multidimensional perovskite solar cells, carbonaceous nanomaterial-based solar cells,
quantum well solar cells, nanowire solar cells, and quantum dot solar cells. The book provides
an in-depth and lucid presentation of the subject matter in an elegant, easy-to-understand writing
style, starting from basic knowledge through principles of operation and fabrication of devices to
advanced research levels encompassing the recent breakthroughs and cutting-edge innovations. It
will be useful for graduate and PhD students, scientists, and engineers.

Nano-Structured Photovoltaics
Solar Cells in the Nanotechnology Era
Vinod Kumar Khanna
Boca Raton London New York
CRC Press is an imprint of the
Taylor & Francis Group, an informa business
First edition published 2023
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CRC Press is an imprint of Taylor & Francis Group, LLC
© 2023 Vinod Kumar Khanna
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ISBN: 978-1-032-07556-3 (hbk)
ISBN: 978-1-032-10403-4 (pbk)
ISBN: 978-1-003-21515-8 (ebk)
DOI: 10.1201/9781003215158
Typeset in Times
by Apex CoVantage, LLC
Dedicated to my beloved parents,
Late Shri Amarnath Khanna and Shrimati Pushpa Khanna,
For my upbringing and education.
My grandson Hansh, daughter Aloka, and wife, Amita,
For their affection and unfailing support.

Contents
Preface .........................................................................................................................................xxiii
Acknowledgments ......................................................................................................................xxvii
About the Author ..........................................................................................................................xxix
About the Book .............................................................................................................................xxxi
Acronyms and Abbreviations ....................................................................................................xxxiii
Chemical Symbols .....................................................................................................................xxxix
Mathematical Symbols .................................................................................................................xliii
Part I Preliminaries and Nanocrystalline
Silicon Photovoltaics
Chapter 1 Solar Cell Basics ..........................................................................................................3
1.1 Progression from Fossil Fuels to Renewable Energy Sources ..........................3
1.1.1 Fossil Fuels, the Lifeblood of Modern Civilization .............................3
1.1.2 Evils and Limitations of Fossil Fuels ...................................................3
1.1.2.1 Land and Habitat Destruction ..............................................3
1.1.2.2 Greenhouse Effect ................................................................3
1.1.2.3 Global Warming ...................................................................3
1.1.2.4 Depletion of Fossil Fuels ......................................................3
1.1.3 Promises of Solar Energy for Sustainable Development .....................4
1.2 Solar Power Generating System ........................................................................5
1.2.1 Photovoltaic Power System ..................................................................5
1.2.2 Concentrated Power System ................................................................5
1.3 Photovoltaic Power System ...............................................................................5
1.3.1 Off-Grid (Stand-Alone or Grid Fallback) Solar Power System ...........5
1.3.2 Grid-Tie Solar Power System ...............................................................5
1.4 Construction and Working of a Solar Cell ........................................................6
1.5 Optoelectrical Characteristics and Parameters of a Solar Cell .........................8
1.5.1 Short-Circuit Current (I ) ...................................................................8
SC
1.5.2 Open-Circuit Voltage (V ) ..................................................................8
OC
1.5.3 Maximum Power (P ) and Maximum Power Point (P ) .................9
M MPP
1.5.4 Fill Factor ...........................................................................................11
1.5.5 Power Conversion Efficiency .............................................................11
1.5.6 AM0 and AM1.5 Solar Spectra ..........................................................11
1.5.7 Shockley-Queisser Detailed Balance Limit of Efficiency
of P-N Junction Solar Cell .................................................................12
1.6 Solar Cell Generations ....................................................................................12
1.6.1 First Generation..................................................................................12
1.6.2 Second Generation .............................................................................12
1.6.3 Third Generation ................................................................................14
1.7 Solar Cell Technologies ...................................................................................14
1.7.1 Monocrystalline Silicon Solar Cell ....................................................14
1.7.2 Gallium Arsenide Solar Cell ..............................................................15
vii
viii Contents
1.7.3 Amorphous Silicon Solar Cell ...........................................................16
1.7.4 Silicon Heterojunction Solar Cell ......................................................16
1.7.5 Cadmium Telluride Solar Cell ...........................................................17
1.7.6 Cadmium Indium Gallium Selenide (CIGSe) Solar Cell ...................18
1.7.7 Perovskite Solar Cell ..........................................................................20
1.7.8 Organic Solar Cell ..............................................................................22
1.7.9 Hybrid Solar Cell ...............................................................................24
1.7.10 Dye-Sensitized Solar Cell ..................................................................24
1.8 Discussion and Conclusions ............................................................................24
References ..................................................................................................................27
Chapter 2 Nanotechnology Fundamentals .................................................................................29
2.1 Nanotechnology...............................................................................................29
2.2 Nanomaterials .................................................................................................29
2.3 0D Nanomaterials ............................................................................................29
2.3.1 Nanoparticle .......................................................................................29
2.3.2 Buckminsterfullerene (C ) ................................................................30
60
2.3.3 Quantum Dot ......................................................................................30
2.4 1D Nanomaterials ............................................................................................32
2.4.1 Nanowire ............................................................................................32
2.4.2 Carbon Nanotube ...............................................................................33
2.5 2D Nanomaterials ............................................................................................37
2.5.1 Graphene ............................................................................................37
2.5.2 2D Perovskites....................................................................................38
2.5.3 Quantum Well ....................................................................................39
2.6 Scope for Nanotechnology Application in Solar Cells and
Organizational Structure of the Book .............................................................41
2.6.1 Use of Nanocrystalline Silicon in Solar Cells ...................................41
2.6.2 Nanotexturing Solar Cell Surface ......................................................41
2.6.3 Using Plasmonic Nanostructures for Maximizing Light
Coupling in Solar Cells ......................................................................42
2.6.4 Further Approaches to Light Incoupling in Solar Cells ....................43
2.6.5 Sensitizing Metal Oxide Semiconductor (TiO) Nanoparticles
2
with Dye .............................................................................................43
2.6.6 Promises of 2D Perovskites Nanomaterials .......................................43
2.6.7 Applications of Carbon Nanostructures ............................................44
2.6.8 Applications of Nanowires .................................................................44
2.6.9 Applications of Quantum Wells .........................................................45
2.6.10 Applications of Quantum Dots ..........................................................45
2.7 Discussion and Conclusions ............................................................................45
References ..................................................................................................................48
Chapter 3 Nanocrystalline Silicon-Based Solar Cells ................................................................49
3.1 Nanocrystalline, Polycrystalline, and Amorphous Silicon Phases as
Photovoltaic Cell Materials .............................................................................49
3.1.1 Nanocrystalline Silicon ......................................................................49
3.1.2 Nanocrystalline vs. Polysilicon ..........................................................49
3.1.3 Amorphous Silicon ............................................................................50
3.1.4 Advantages of Nanocrystalline Silicon over Amorphous and
Polysilicon ..........................................................................................50
Contents ix
3.2 Plasma-Enhanced Chemical Vapor Deposition of a-Si:H and
nc-Si:H Films...................................................................................................50
3.2.1 Effect of Hydrogen Dilution ...............................................................50
3.2.2 High-Pressure Depletion (HPD) Regime ...........................................51
3.3 Silicon Heterojunction (SHJ) Solar Cell .........................................................51
3.3.1 Fabrication of the Solar Cell ..............................................................51
3.3.2 Process Sequence ...............................................................................52
3.3.3 Back Surface Field (BSF) ..................................................................52
3.4 Front- and Rear-Emitter Silicon Heterojunction Solar Cell ............................52
3.4.1 Front-Emitter Solar Cell .....................................................................52
3.4.2 Rear-Emitter Solar Cell ......................................................................52
3.4.3 Advantages of Rear-Emitter Design ..................................................55
3.5 Replacement of Amorphous Silicon by Nanocrystalline Silicon
as Electron/Hole Collectors ............................................................................55
3.5.1 Reasons for Replacement ...................................................................55
3.5.2 Effects of Replacement .......................................................................55
3.6 Nanocrystalline N-Type Silicon Oxide Films as Front Contacts
in Rear-Emitter Solar Cells .............................................................................57
3.6.1 Effect of Refractive Index Matching of Two Optical Media
upon Reflection of Light at Their Interface .......................................57
3.6.2 Comparing Reflectances at the Interfaces a-Si:H/TCO,
nc-Si:H/TCO, and nc-SiO:H/TCO ....................................................57
2
3.6.3 Difficulty in Deposition of Thin nc-SiO:H Film Over
2
(I)a-Si:H Layer ...................................................................................58
3.7 Nanocrystalline Silicon Thin-Film Solar Cell on Honeycomb-Textured
Substrate ..........................................................................................................58
3.8 Discussion and Conclusions ............................................................................58
References ..................................................................................................................62
Part II Nanotechnological Approaches to Sunlight
Harvesting
Chapter 4 Nanotextured-Surface Solar Cells .............................................................................67
4.1 Optical Losses in a Solar Cell and Loss-Reduction Approaches ...................67
4.1.1 Optical Losses ....................................................................................67
4.1.2 Optical Loss Reduction by Optical Transmittance Enhancement ....67
4.1.3 Optical Loss Reduction by Optical Path Lengthening ......................67
4.2 Optical Transmittance Enhancement by Nanotexturing ................................68
4.2.1 Reflectance and Transmittance Equations .........................................68
4.2.2 Effects of Sizes of Structures of the Textured Interface
Morphology on its Reflectance ..........................................................70
4.3 Nanotextured Surface Properties, Examples in Nature, and
Comparison with Microtexturing ...................................................................72
4.3.1 Self-Cleaning Property of Nanotextured Surfaces ............................72
4.3.2 Moth-Eye Nanostructured Surfaces ..................................................72
4.3.3 Nanotexturing vs. Microtexturing .....................................................73
4.4 Nanotextured Silicon Solar Cell Fabrication ..................................................74
4.4.1 Inverted Nanopyramid Crystalline Silicon Solar Cell by a
Maskless Technique (η = 7.12%) ........................................................74