Organometal Halide Perovskite Solar Absorbers and Ferroelectric Nanocomposites for Harvesting

199 Pages·2017·6.24 MB·English

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USF Tampa Graduate Theses and Dissertations USF Graduate Theses and Dissertations
November 2017
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Chaminda Lakmal Hettiarachchi
University of South Florida, [email protected]
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Organometal Halide Perovskite Solar Absorbers and Ferroelectric Nanocomposites for
Harvesting Solar Energy

by

Chaminda Lakmal Hettiarachchi

A dissertation submitted in partial fulfillment
of the requirements for the degree of
Doctor of Philosophy
Department of Physics
College of Arts and Sciences
University of South Florida

Co-Major Professor: Sarath Witanachchi, Ph.D.
Co-Major Professor: Pritish Mukherjee, Ph.D.
Hariharan Srikanth, Ph.D.
Denis Karaiskaj, Ph.D.
Manh-Huong Phan, Ph.D.

Date of Approval:

Keywords: Organolead Halides, BaTiO nanoparticles, Ferroelectric Polarization, UV-Vis-NIR
3
Spectroscopy, X-ray Diffraction, Scanning Electron Microscopy,
Aerosol Assisted Chemical Vapor Deposition

Copyright © 2017, Chaminda Lakmal Hettiarachchi
DEDICATION
I dedicate my dissertation work to my parents and my family. First, a special feeling of gratitude
to my loving parents, Mr. Hettiarachchige Don Albert and Mrs. Subaddarage Somawathie for their
endless love and kindness shown me over the years. Then, to my wife Wasana who has been a
constant source of support and encouragement during balancing the challenges of graduate school
and family life. And to Dylan, Dan, Sathini, and Sayumi for making me happy, giving me strength
to complete this work.
ACKNOWLEDGMENTS

First and foremost, I would like to express my deepest gratitude to Dr. Sarath Witanachchi
and Dr. Pritish Mukherjee. I’m indebted to them for their immeasurable support, guidance,
encouragement, and academic advice. I greatly appreciate their contributions of time, ideas,
funding, and opportunity given me to make my Ph.D. work on solar cells. Their incredible
problem-solving skills were immensely helpful in moving my project forward. Thank you for
making me innovative and pushing me beyond the boundaries. I will remember my time with Dr.
Witanachchi in the social events as well.
I would like to thank my dissertation committee chair Dr. Sameer Varma and members Dr.
Hariharan Srikanth, Dr. Denis Karaiskaj, and Dr. Manh-Huong Phan for serving on my dissertation
committee. Thank you, Dr. Phan for checking the progress of my work and encouraging words.
Special thank is given to Dr. Robert Hyde for his extended support during tough times,
technical support, time, ideas, training, and his great humanity. Most of the hands-on experience
and skills on fabrication and characterization of thin films I gained from him.
I have had the pleasure to work with my colleagues Mahesh Hordagoda, Dr. Dino
Ferizovic, Jason Rejman, Domingo Feliciano, Marek Merlak, and Daniel Denmark. Thank you for
your friendship, valuable assistance and ideas during our time in the laboratory. Thank you Daniel
Hormalik for the initial work on thermal evaporator which I completed fabrication. And thanks
Dr. Prasana Sahoo for PL measurements of perovskite thin films. I would also like to thank the
undergraduate and REU students I supervised over the past several years, namely Constance
Owens, Nicholas Valdes, John Niman, Nicholas Harris, Daniel Morales, and Chad Wilder.
I would also like to thank present and past Physics department staff for their assistance in
numerous ways over the years; Daisy Matos, James Christopher, Candice Pietri, Jimmy Suarez,
Mary Ann Prowant, Philip Burgeron, Luisa Odeja, Flora Luna, and Mary Wengyn.
This work was partially supported by the United States Army under grant number
W81XWH1020101/3349 and the National Science Foundation Research Education for
Undergraduates under grant number DMR1263066.
TABLE OF CONTENTS
List of Tables .................................................................................................................... iv

List of Figures ......................................................................................................................v

List of Abbreviations .................................................................................................................... xi

Abstract ................................................................................................................. xvii

Chapter 1: Introduction ....................................................................................................................1
1.1. Perovskite Solar Absorbers ...........................................................................................2
1.2. Organometal Halide Perovskites...................................................................................3
1.3. Methylammonium Lead Halide Perovskites .................................................................5
1.3.1. Temperature Dependent Structural Properties .............................................9
1.4. Bandgap Engineering of Perovskite Materials ...........................................................11
1.4.1. Influence of A Cation.................................................................................12
1.4.2. Influence of B Cation .................................................................................13
1.4.3. Influence of X Anion .................................................................................14
1.5. Perovskite Solar Cells Structures ................................................................................14
1.6. Operational Principals of Perovskite Solar Cells ........................................................16
1.7. Hysteresis ....................................................................................................................20
1.7.1. Ferroelectric Polarization ...........................................................................21
1.7.2. Charge Trapping/Detrapping .....................................................................23
1.7.3. Ion Migration .............................................................................................24
1.8. Stability ....................................................................................................................25
1.8.1. Effect of Moisture in the Dark ...................................................................25
1.8.2. Effect of Light Coupled with Moisture and Oxygen .................................27
1.8.3. Effect of Heat .............................................................................................29
1.9. Ferroelectric Nanocomposites ....................................................................................33
1.9.1. Barium Titanate (BaTiO or BTO) Nanoparticles .....................................35
3
1.10. Research Objective ...................................................................................................38
1.11. Dissertation Outline ..................................................................................................39

Chapter 2: Experimental Techniques .............................................................................................40
2.1. Thin Film Deposition ..................................................................................................40
2.1.1. Aerosol Assisted Chemical Vapor Deposition ............................................44
2.1.2. Spin Coating.................................................................................................46
2.2. Electrode Deposition ...................................................................................................49
2.2.1. Thermal Evaporation ...................................................................................49
2.3. Structural Characterization .........................................................................................51
2.3.1. X-ray Diffraction .........................................................................................52
I
2.3.2. Scanning Electron Microscopy ................................................................................55
2.3.3. Energy Dispersive X-ray Microscopy .....................................................................58
2.3.4. Profilometry .............................................................................................................59
2.4. Optical Characterization .............................................................................................60
2.4.1. UV-vis-NIR Spectroscopy ...........................................................................62
2.5. Electrical Characterization ..........................................................................................63
2.5.1. Current-Voltage Measurements ...................................................................64
2.6. Ferroelectric Characterization .....................................................................................66
2.7. Chapter Summary .......................................................................................................66

Chapter 3: Development of a Novel Single-Step Growth Process for the Deposition of
CH NH PbI Cl Perovskite Films from CH NH Cl and PbI Precursors .................67
3 3 3-x x 3 3 2
3.1. Synthesis of CH NH PbI Cl Perovskite Precursors ................................................68
3 3 3-x x
3.2. Deposition of CH NH PbI Cl Perovskite Thin Films .............................................68
3 3 3-x x
3.3. Results and Discussion ...............................................................................................69
3.3.1. Structural Characterization ..........................................................................69
3.3.2. Optical Characterization ..............................................................................76
3.3.3. Post-Deposition Annealing of Perovskite Thin Films .................................84
3.4. Growth and Characterization of CH NH PbI Cl perovskite thin films via
3 3 3-x x
Solution Casting Method .............................................................................................88
3.5. Growth and Characterization of CH NH PbI Cl perovskite thin films via
3 3 3-x x
Spin Coating Method ..................................................................................................91
3.6. Chapter Summary .......................................................................................................93

Chapter 4: BTO: CH NH PbI Cl Nanocomposites ...................................................................94
3 3 3-x x
4.1. Synthesis of BTO: CH NH PbI Cl Perovskite Nanocomposite ............................95
3 3 3-x x
4.2. BTO: CH NH PbI Cl Perovskite Nanocomposite Deposition by Aerosol
3 3 3-x x
Assisted Chemical Vapor Deposition .........................................................................95
4.3. Results and Discussion ...............................................................................................97
4.3.1. Structural Characterization ..........................................................................97
4.3.2. Optical Characterization ............................................................................102
4.3.3. Ferroelectric Characterization ....................................................................104
4.4. Chapter Summary .....................................................................................................106

Chapter 5: A Simple Model to Guide the Optimum BTO Nanoparticle Concentration in the
BTO: CH NH PbI Cl Perovskite Nanocomposite .................................................107
3 3 3-x x
5.1. Electric Field due to 4 electric dipoles ......................................................................109
5.2. Electric Field Within a Unit Cell due to 8 Electric Dipoles .....................................111
5.3. Electric Field Within a Unit Cell due to 16 Electric Dipoles ...................................114
5.4. Volume Fraction of Perovskite Solar Absorber ........................................................117
5.5. Optimum BTO Nanoparticle Concentration .............................................................118
5.6. Chapter Summary .....................................................................................................120

Chapter 6: Development of CH NH PbI Cl Perovskite Solar Cells with and without
3 3 3-x x
BTO Nanoparticles ....................................................................................................121
6.1. CH NH PbI Cl Perovskite Solar Cell Structures……………………………….. 121
3 3 3-x x
II
6.2. Deposition of ETL and Characterization………………………………………….. 125
6.2.1. Deposition of TiO by Spin Coating Method ............................................125
2
6.2.2. Structural Characterization of TiO Thin Films .........................................125
2
6.2.3. Optical Characterization of TiO Thin Films .............................................126
2
6.3. Deposition of CH NH PbI Cl Perovskite Layer without BTO Nanoparticles and
3 3 3-x x
Characterization .........................................................................................................127
6.4. Deposition of CH NH PbI Cl Perovskite Layer with BTO Nanoparticles
3 3 3-x x
and Characterization ..................................................................................................127
6.5. Deposition of HTL and characterization ...................................................................127
6.5.1. Deposition of P3HT with Additives by Spin Coating Method ..................127
6.5.2. Structural Characterization of P3HT Thin Films with Additives ..............128
6.5.3. Optical Characterization of P3HT with Additives .....................................129
6.6. Development of Perovskite Solar Cells ....................................................................129
6.6.1. J-V Characteristics of Solar Cell without BTO Nanoparticles ..................130
6.6.2. J-V Characteristics of Solar Cell with BTO Nanoparticles .............................131
6.7. Chapter Summary .....................................................................................................134

Chapter 7: Conclusions ................................................................................................................135

References ..................................................................................................................139

Appendices ..................................................................................................................165
Appendix A ..................................................................................................................166
Appendix B ..................................................................................................................170
Appendix C ..................................................................................................................172
Appendix D ..................................................................................................................174

About the Author ........................................................................................................ End Page

III
LIST OF TABLES

Table 1.1: Properties of different lead halide perovskites. Reproduced with permission
from Bretschneider et al., APL Materials 2, 40701, (2014). Copyright 2017 AIP
Publishing ......................................................................................................................6

Table 1.2: Estimation of the A cation radii in ABX . Reproduced with permission from Kim
3
et al., Journal of Physical Chemistry C, 118 (11), pp 5615–5625 (2014),
Copyright 2014 American Chemical Society. ................................................................. 8

Table 1.3: Temperature-dependent structural data of CH NH PbI . Reprinted with permission
3 3 3
from Kim et al., Journal of Physical Chemistry C, 118 (11), pp 5615–5625 (2014).
Copyright 2014 American Chemical Society ................................................................9

Table 1.4: Decomposition temperature and the stable temperature of several perovskite
materials Reprinted from Progress in Materials Science, 87, G. Han, S. Zhang,
P. P. Boix, L. H. Wong, L. Sun, S. Y. Lien, Towards High Efficiency Thin Film
Solar Cells, Copyright 2014, with permission from Elsevier ......................................30

Table 1.5: Summary of the critical sizes obtained through different methods .............................37

Table 3.1: FWHM for samples (b) to (f) .......................................................................................71

Table 3.2: 110:220 peak ratios for sample (b) to (f) .....................................................................71

Table 3.3: Effect of PbI and MACl concentrations on the Pb:I:Cl of AACVD
2
fabricated perovskite films ...........................................................................................83

Table 4.1: BTO masses used for the deposition of BTO: perovskite nanocomposites .................95

Table 5.1: Maximum Electric field between the planes ..............................................................116

Table 5.2: Variation of Volume Fraction of the perovskite absorber within the cubic volume
as a function of distance between nanoparticles a .....................................................117

IV
LIST OF FIGURES

Figure 1.1: Crystalline systems of perovskites. Adapted from [107] with permission of
The Royal Society of Chemistry ..............................................................................3

Figure 1.2: Crystal structure of organometal halide perovskites. Adapted by permission
from Macmillan Publishers Ltd: [Nature] (42), copyright (2013) ...........................4

Figure 1.3: Scheme ([006] view) of phase transitions of lead halide perovskite. The
high-temperature α-phase has two possible phase t ransitions, for dry
crystals to the β- (T < 327 K) and γ -phase (T < 162 K) or in the presence
of, e.g., a solvent to the δ-phase for temperature below ∼360 K. Stoumpos
et al., Inorganic Chemistry52(15), 9019 (2013). Copyright 2014 American
Chemical Society ...................................................................................................11

Figure 1.4: Candidates for B cation from the periodic table of elements. Adapted from
[58] with permission of the Monatshefte fü Chemie/chemical Monthly.
Copyright 2017 Springer........................................................................................13

Figure 1.5: Typical structures for perovskite solar cells ..........................................................15
Figure 1.6: Open-circuit voltage versus optical bandgap. Reprinted with permission from
Henry J. Snaith, Journal of Physical Chemistry Letters, 2013, 4 (21), pp 3623–
3630. Copyright 2013 American Chemical Society ..............................................19

Figure 1.7: Typical hysteresis curve of a ferroelectric material ...............................................33

Figure 1.8: Temperatures of C/T, T/O and O/R transitions versus grain size of BTO
nanoparticles. Adapted from (147) with permission of the Journal of
Advanced Ceramics. Copyright 2015 Springer .....................................................36

Figure 2.1: (a) single-step solution deposition, (b) two-step solution deposition, (c) two-
step hybrid deposition, and (d) thermal vapor deposition. Reproduced from
[179] with permission from 2016, Society of Photo-Optical Instrumentation
Engineers (SPIE). ...................................................................................................41

Figure 2.2: Solution processing techniques. Reproduced from [5] with permission
from the Science and Technology of Advanced Materials ....................................42
V