NATURAL COLORANTS AS PHOTOSENSITIZER FOR DYE-SENSITIZED SOLAR CELLS (DSSCs) FOR GREEN ECONOMY By Ayesha Altaf DEPARTMENT OF ENVIRONMENTAL SCIENCE LAHORE COLLEGE FOR WOMEN UNIVERSITY, LAHORE, PAKISTAN 2018 NATURAL COLORANTS AS PHOTOSENSITIZER FOR DYE-SENSITIZED SOLAR CELLS (DSSCs) FOR GREEN ECONOMY A THESIS SUBMITTED TO LAHORE COLLEGE FOR WOMEN UNIVERSITY IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSPHY IN ENVIRONMENTAL SCIENCE By Ayesha Altaf Registration No. 14-PhD/LCWU-193 Supervisor: Prof. Dr. Tahira Aziz Mughal Co-Supervisor: Dr. Zafar Iqbal DEPARTMENT OF ENVIRONMENTAL SCIENCE LAHORE COLLEGE FOR WOMEN UNIVERSITY, LAHORE, PAKISTAN 2018 Declaration Form This is to certify that the research work described in this thesis submitted by Mrs. Ayesha Altaf to Department of Environmental Sciences, Lahore College for Women University has been carried out under my direct supervision. I have personally gone through the raw data and certify the correctness and authenticity of all results reported herein. I further certify that thesis data have not been use in part or full, in a manuscript already submitted or in the process of submission in Partial/complete fulfillment of the award of any other degree from any other institution or home or abroad. I also certified that the enclosed manuscript, has been to paid under my supervision and I endorse its evaluation for the award of Ph.D degree through the official procedure of University. ________________ __________________ Prof. Dr. Tahira Aziz Mughal Dr. Zafar Iqbal (Supervisor) (Co- Supervisor) Date: ___________ Date: ___________ _________________ Date: ___________ External Examiner ________________ Date: ___________ Chairperson Department of Environmental Science LCWU, Lahore Stamp ______________________ Controller of Examination LCWU, Lahore. Stamp Date: ___________ DEDICATION My deepest thanks to my dearest husband Hassan Mahmood My darling sons Musa Hassan & Essa Hassan My beloved Parents Mr. & Mrs. Mian Muhammad Altaf My ever-supporting Siblings & My respected Supervisors Thank you all for your unconditional love and support I love you with all my heart ACKNOWLEDGEMENTS "He (Allah the Almighty) taught (man) the use of pen (the basic implement in field of knowledge) and taught man which he knew not." (Al-Quran) ,the Most Gracious, the Most Merciful, all praise be to Allah ,ﷻ In the name of Allah the Lord of the Worlds; and Allah's peace and blessings be upon our Prophet First and foremost, I bow my head before Allah-The Almighty .ﷺ Muhammad with humble thanks and gratitude for His help and bless that enabled me to accomplish this hard task. I am absolutely sure that this dream would have never become reality without His guidance. All of my loves are for Hazrat Muhammad .a light of leadership for all mankind evermore ,(ﷺ) My journey of Ph.D was just like rock climbing step by step together with hardships, faith, frustration and encouragement. At this moment of success, I wish to acknowledge few individuals and institutions who helped me in completing this research and dissertation. I owe a profound debt of gratitude to my supervisor Prof. Dr. Tahira Aziz Mughal, chairperson, Environmental Science Department for her keen interest, valuable suggestions, enthusiastic guidance, affectionate behavior, encouragement and support throughout the research work. I would like to pay thanks for her great understanding and maternal support during this whole study period. My profound and cordial thoughts are for my co-supervisor Dr. Zafar Iqbal, Senior Scientific Officer, PCSIR Laboratories Complex, Lahore for his kind and professional attitude and scholarly discussions. I highly appreciate his efforts during all phases of this research. Under his guidance, I successfully overcame many hurdles and learnt a lot from him. I highly appreciate and acknowledge the support I received from few institutions and laboratories. I would like to express my sincere thanks and I am also indebted to Dr. Safeer Ahmad from Quaid-e-Azam University, Islamabad and Dr. Rehana Shareef, University of Engineering and Technology, Lahore for the provision of research facilities. I am equally thankful Dr. Khalid, Associate Professor, Forman Christian College, Lahore for the provision of laboratory and equipment. I am very grateful to all of my colleagues, friends and research fellows who remain very supportive and generous throughout this research tenure. Special thanks to my studious senior and best friend Dr. Ambreen Aslam & Ms. Rabia Majeed for their ever encouraging attitude and Dr. Shaista Imran for being so considerate and kind. My appreciations are for all of my Ph.D fellows as their applause raised my confidence to become fortunate. Their suggestions and assistance during my whole research made me able to be at apex. The prayers and support of my parents Mr & Mrs Mian Muhammad Altaf and siblings are really remarkable. They have been so perceptive and caring. They proved to be a pure helping hand that facilitates against the pangs faced during my research. I love to acknowledge them for their involvement and guidance during my whole phase. Finally, I acknowledge the person who mean everything to me, my husband, Hassan Mahmood for his absolute love, understanding and support which enabled me to fulfill my dream and made the completion of thesis possible. I extremely value his contributions and heartily appreciate his faith in me. He is always around at times I thought it is impossible to pursue further. It is because of his efforts that today I can proudly stand with my head held high. The true crown of gratefulness goes to my beloved sons Musa Hassan and Essa Hassan for surviving my negligence and being patient during my thesis writing. Words never express how grateful I am to all of you. My heartfelt regards goes to my father in law, mother in law and all other family members for their love and moral support. Last but not least, I wish to express my sincere thanks to all those who helped me in making this study a success. Ayesha Altaf i CONTENTS TITLE Page No. List of Figures iii List of Tables viii List of Plates x List of Abbreviations xii Abstract xiv Chapter 1 Introduction 01 1.1. Global Energy Crisis 01 1.2. Energy Status of Pakistan 02 1.3. Solar Energy Scenario of Pakistan 04 1.4. Photovoltaic Technology and Third Generation Solar Cells 06 1.5. Operating Principle of Dye-Sensitized Solar Cells 06 1.6. Photo-Sensitizers for Dye-Sensitized Solar Cells 09 1.7. Importance of Natural Dyes Over Synthetic dyes 09 1.8. Objectives 10 Chapter 2 Review of Literature 12 Chapter 3 Materials and Methods 28 3.1. Selection of Study Area 28 3.2. Selection of Plants 29 3.3. Identification of Suitable Plants 31 3.4. Sorting and Coding of Plants 31 3.5. Extraction of Colorants from Plants 33 3.5.1. Cold Maceration 32 3.5.2. Pretreatment of Plant Samples for Maceration 33 3.5.3. Maceration and Filtration 33 3.5.4. Solvent Extraction 34 3.6. Storage of Natural Dye Extracts 35 3.7. Characterization of Extracted Natural Dye for DSSCs 35 ii 3.7.1. Photo-physical Characterization 35 3.7.1.1. UV-Visible Spectrophotometry 35 3.7.2. Electro-chemical Characterization 35 3.7.2.1. Cyclic Voltammetry 36 3.8. Fabrication of Dye-Sensitized Solar Cells with Natural Dye 36 Extracts 3.8.1. Preparation of working Electrode 36 i. Cleaning of FTO glass ii. Blocking Layer (TiCl4) Treatment iii. Preparation and Application of TiO2 Paste iv. Natural Dye Adsorption 3.8.2. Preparation of Counter Electrode 38 3.8.3. Electrolyte 38 3.9. Assembling and Performance Characterization of Natural Dye- 38 Sensitized Solar Cells 3.10. Data Interpretation and Efficiency Measurement 39 3.11. Photovoltaic Parameters to Evaluate the Performances of 39 DSSCs 3.11.1 Short Circuit Current Density 40 3.11.2 Open Circuit Voltage 40 3.11.3 Fill Factor 40 3.11.4 Power Conversion Efficiency 41 3.12. Economic Suitability of Extracted natural Dyes 41 Chapter 4 Results 42 Chapter 5 Discussion 127 Conclusion 132 References 133 Plates 148 Plagiarism Report List of Publications and Reprints xv iii LIST OF FIGURES Sr. No. TITLE Page No. 1.1 Schematic representation of a typical Dye- 7 Sensitized Solar Cell (DSSC) 1.2 Categories of photo-sensitizers for DSSCs 9 4.1 UV-Visible absorption spectra of D1-A 44 4.2 UV-Visible absorption spectra of D2-A 44 4.3 UV-Visible absorption spectra of D3-A 45 4.4 UV-Visible absorption spectra of D4-A 45 4.5 UV-Visible absorption spectra of D5-A 47 4.6 UV-Visible absorption spectra of D6-A 47 4.7 UV-Visible absorption spectra of six natural dye 48 sensitizers (D1-A_D6-A) 4.8 Cyclic voltammogram of D1-A dye 50 4.9 Cyclic voltammogram of D2-A dye 50 4.10 Cyclic voltammogram of D3-A dye 51 4.11 Cyclic voltammogram of D4-A dye 51 4.12 Cyclic voltammogram of D5-A dye 53 4.13 Cyclic voltammogram of D6-A dye 53 4.14 Cyclic voltammograms of individual dye extracts 54 of six samples of flowers of A-Category (D1- A_D6-A) 4.15 J-V characteristics curve of H. rosa-sinensis (D1- 56 A) 4.16 J-V characteristics curve of B. oleracea var. 56 capitata (D2-A) 4.17 J-V characteristics curve of C. argentea (D3-A) 57 4.18 J-V characteristics curve of R. damascena (D4-A) 57 iv 4.19 J-V characteristics curve of R. macdub (Yellow) 59 D5-A 4.20 J-V characteristics curve of R. macdub (Red) D6- 59 A 4.21 Comparison of J-V characteristics curves of 60 individual dye sensitizers (D1-A_D6-A) for DSSCs 4.22 UV-Visible absorption spectra of D7-B 62 4.23 UV-Visible absorption spectra of D8-B 62 4,24 UV-Visible absorption spectra of D9-B 64 4.25 UV-Visible