Effect of Annealing Temperature on the Formation of Methylammonium Tin Tri-Iodide Perovskite Thin Film

Effect of Annealing Temperature on the Formation of Methylammonium Tin Tri-Iodide Perovskite Thin Film.

ABSTRACT

Organic-inorganic perovskite photovoltaics (PVs) have attracted a lot of attention as high-efficiency thin-film PVs which are relatively cheap and easy to fabricate. Lead halide perovskites have shown a rapid rise in power conversion efficiency by 3.8 % in 2009 to 21.02 % in 2016.

One major problem is that lead is toxic and poses a serious concern to health and the environment. The most likely substitute for lead is tin. Tin-based perovskite solar cells have shown good semiconducting properties but still have very low efficiencies. The major challenge is the instability of tin in its +2 oxidation state.

The photovoltaic performance and life span of these solar cells depend greatly on the film morphology. The morphology depends on the deposition technique and the subsequent treatment employed. In this work, we investigated the effect of post-annealing temperature on the formation of methylammonium tin tri-iodide (CH3NH3SnI3).

TABLE OF CONTENTS

ABSTRACT iii
ACKNOWLEDGMENT iv
DEDICATION v
CONTENTS vi
LIST OF FIGURES ix
LIST OF TABLES x
CHAPTER ONE 1
GENERAL INTRODUCTION 1
1.1 Problem Definition 1
1.2 Aim and Objectives 2
1.3 Outline of Thesis 2
CHAPTER TWO 3
FUNDAMENTALS OF PV TECHNOLOGY 3
2.1 Solar Energy and Solar Power 3
2.2 PVs 3
2.3 Evolution of Solar Cells 3
2.3.1 First Generation 3
2.3.2 Second Generation 4
2.3.3 Third Generation 5
2.3.4 Multi-junction Solar Cells (Tandem Junction Solar Cells) 8
CHAPTER THREE 28
EXPERIMENTAL PROCEDURE 28
3.1 Equipment 28
3.2 Chemicals 28
3.3 Fabrication of Perovskite Layer 28
3.3.1 Cleaning of Glass Slides 28
3.3.2 Sequential Thermal Vacuum Deposition of CH3NH3SnI3 29
3.3.3 Annealing of CH3NH3SnI3 30
3.4 Characterizations of CH3NH3SnI3 Perovskite 31
3.4.1 Optical Measurement 31
3.5 Electrical Measurement 31
3.5.1 X-ray Diffraction (XRD) 32
CHAPTER FOUR 33
RESULTS AND DISCUSSIONS 33
4.1 Variation of Transmittance with Annealing Temperature 33
4.2 Stability of Un-Annealed and Annealed Films in Air 33
4.3 Absorption Coefficient, α 34
4.4 Variation Surface Roughness with Annealing Temperature 35
4.5 Resistivity 37
4.6 X-ray Diffraction (XRD) 38
CHAPTER FIVE 41
CONCLUSION AND RECOMMENDATIONS FOR FUTURE WORK 41
REFERENCES 42

INTRODUCTION

The demand for energy is increasing and the danger of global warming due to CO2 emissions are the tremendous future challenges for mankind. It is well known that the use of conventional energy sources (coal, natural gas, and petroleum) contribute a huge amount of CO2 to the environment.

There is, therefore, growing need for alternative energy sources that are green and sustainable. Solar power is the world’s most abundant energy resource [1]. A year’s worth of sunlight contains 1.5x 1018 kW h of energy.

Harvesting solar energy is an essential approach to providing green and sustainable energy. One way of harvesting from the sun is by the use of photovoltaics or solar cells.

REFERENCES

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[3] S. Chu and A. Majumdar, “Opportunities and challenges for a sustainable energy future,” Nature, vol. 488, no. 7411, pp. 294–303, Aug. 2012.

[4] M. Mcgehee, “Emerging High-Efficiency Low-Cost Solar Cell Technologies.”

[5] A. Kojima, K. Teshima, Y. Shirai, and T. Miyasaka, “Organometal Halide Perovskites as Visible-Light Sensitizers for Photovoltaic Cells,” J. Am. Chem. Soc., vol.131, no. 17, pp. 6050–6051, May 2009.

[6] A. R. bin M. Yusoff and M. K. Nazeeruddin, “Organohalide Lead Perovskites for Photovoltaic Applications,” J. Phys. Chem. Lett., vol. 7, no. 5, pp. 851–866, Mar. 2016.

[7] P. Wang, Y. Guo, S. Yuan, C. Yan, J. Lin, Z. Liu, Y. Lu, C. Bai, Q. Lu, S. Dai, and C. Cai, “Advances in the structure and materials of perovskite solar cells,” Res. Chem. Intermed., vol. 42, no. 2, pp. 625–639, Feb. 2016.

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