Solvo-hydrothermal growth and photoluminescence studies of micro and nano structured Zinc Sulfide for bio-imaging applications Thesis submitted to COCHIN UNIVERSITY OF SCIENCE AND TECHNOLOGY in partial fulfillment of the requirements for the award of the degree of DOCTOR OF PHILOSOPHY in Physics by Sajan P. Nano Functional Materials Lab Department of Physics Cochin University of Science and Technology Cochin - 682 022, Kerala, India June 2016 Solvo-hydrothermal growth and photoluminescence studies of micro and nano structured Zinc Sulfide for bio-imaging applications Ph.D. thesis in the field of Physics Author: Sajan P. Nano Functional Materials Lab Department of Physics Cochin University of Science and Technology Cochin - 682 022, Kerala, India. Email: [email protected] Supervisor: Dr. M. Junaid Bushiri Professor Nano Functional Materials Lab Department of Physics Cochin University of Science and Technology Cochin-682 022, Kerala, India. Email: [email protected] June 2016 Dedicated to my mother Department of Physics Cochin University of Science and Technology Cochin – 682 022 Dr. M. Junaid Bushiri Professor Department of Physics Cochin University of Science and Technology Cochin 682 022, India. Certified that the work presented in this thesis entitled “Solvo-hydrothermal growth and photoluminescence studies of micro and nano structured Zinc Sulfide for bio- imaging applications” is based on the bonafide record of research work done by Sajan P., under my guidance in the Department of Physics, Cochin University of Science and Technology, Cochin 682 022 in partial fulfillment of the requirements for the award of degree of Doctor of Philosophy and has not been included in any other thesis submitted for the award of any degree. All the relevant corrections and modifications suggested by the audience during the pre-synopsis seminar and recommendations by doctoral committee of the candidate have been incorporated in the thesis. Cochin-22 Dr. M. Junaid Bushiri Date:15/06/2016 (Supervising Guide) Phone: +91-4842577404 Fax: 91 484 2577595, Email: [email protected] Certified that the work presented in this thesis entitled “Solvo- hydrothermal growth and photoluminescence studies of micro and nano structured Zinc Sulfide for bio-imaging applications” is based on the original work done by me under the guidance of Dr. M. Junaid Bushiri, Professor, Department of Physics, CUSAT, Cochin-22 and has not been included in any other thesis submitted previously for the award of any other degree. Cochin – 22 Sajan P. Date:15/06/2016 Acknowledgements At this particular juncture, when I look back with full of memories, I could realize that there are too many peoples to thank for their unconditional love and help. This thesis will not be completed without their support and help. It is a pleasant task and I use this occasion to express my thanks to all my teachers and friends from my school days onwards. First and foremost, I obliged to Prof. M. Junaid Bushiri, my supervising guide and teacher for his valuable advice, help and support throughout the research period. He was always ready to hear me, discuss with the research problems and share new ideas. I also thank him for his help and support. I express my sincere thanks to Prof. S. Jayalekshmi, Head, Department of Physics CUSAT, and all the former heads- Prof. B. Pradeep, Prof. M. R. Anantharaman for providing and permitting me to use the research facilities in the department. I sincerely thank Prof. M. R. Anantharaman, my Doctoral committee member, for all his support, advice and help. I express my gratitude to all the teachers and non-teaching staff in Department of Physics CUSAT, for their help and support. It is my pleasure and proud to thank my mentor Mr. Joseph Sir, Teacher St. Mary’s A U P School Mamankara for his cares and support. I would like to thank Sebastian Sir, Madhusoodanan and Eliamma teacher for their support during my school days. I am obliged to Prof. M. K. Jayaraj, Professor, Department of Physics CUSAT and Department of Physics, Madurai Kamaraj University, Tamilnadu for allowing me to take the Raman and PL measurements. I thank Dr. Shibu M Eappen and Mr. Melbin SAIF STIC CUSAT for SEM measurements. I would like to thank S. Agouram, Departamento de Fisica Aplicada y Electromagnetismo, Universitat de, Valencia, C/Dr Moliner 50 Burjassot, Valencia 46100, Spain, SAIF IIT Madras, and TEM facility at School of Pure and Applied Physics, MG University Kottayam for TEM measurements. Words are not enough to thank Dr. R. S. Jayasree, Scientist, Biophotonics and Imaging Laboratory Biomedical Technology Wing, Sree Chitra Tirunal Institute for Medical Sciences & Technology, Poojappura, Thiruvananthapuram for bio-imaging studies of the samples. I acknowledge University Grants Commission India for providing Rajiv Gandhi National Fellowship during the research period. The research at my lab, Nano Functional Materials Lab was unforgettable moments and I thank my lab members Bini, Shajira, Vinod, Ganesh, Satheesh, Rasheed, Sagar, Beena, M Phil and M Sc project students for their help and support. I thank all my school, B. Sc, M. Sc classmates, seniors, friends from other labs of the department and Bro Bro team members (Jubeesh, Abhi, Navaneeth, Shijeesh, Anand, Santhu, Deepu, Aravind, Titu, Manoj, Anshad, Jishnu, Dinto, Sreejith, Kurias, Abhay, Manu) for making a joyful life at CUSAT. I have no words to express my gratitude and feelings towards my Amma for her unconditional love, caring and support throughout my life. I thank all my family members for their help and support. Finally I thank all my well-wishers and friends who have supported me. Sajan. P Contents Preface 1. Basics of nanoscience and nanotechnology ------------------------------------------1 1.1. Introduction --------------------------------------------------------------------------- 1 1.2. Properties of nanomaterials -------------------------------------------------------- 2 1.2.1. Mechanical properties ----------------------------------------------------- 2 1.2.2. Thermal properties ---------------------------------------------------------- 3 1.2.3. Magnetic properties -------------------------------------------------------- 4 1.2.4. Optical properties ----------------------------------------------------------- 5 1.2.5. Physicochemical and biological properties ------------------------------ 6 1.3. Semiconductor nanoparticles ------------------------------------------------------- 7 1.4. Types of Semiconductor nanoparticles -------------------------------------------- 8 1.4.1. Two Dimensional (2D) Nanostructures:Quantum Well ------------ 9 1.4.2. One Dimensional (1D) Nanostructures: Quantum Wire ------------ 9 1.4.3. Zero Dimensional (0D) Nanostructures: Quantum dot ------------ 10 1.4.4. Confinement regime -------------------------------------------------------- 10 1.5. Nanophosphors ---------------------------------------------------------------------- 11 1.6. Luminescence ------------------------------------------------------------------------ 13 1.6.1. Photoluminescence --------------------------------------------------------- 14 1.6.1.1. Fluorescence ------------------------------------------------------ 14 1.6.1.2. Phosphorescence ------------------------------------------------- 15 1.6.2. Types of Photoluminescence ---------------------------------------------- 15 1.6.2.1. Intrinsic Luminescence ----------------------------------------- 15 1.6.2.1a). Band-to-band luminescence --------------------------- 15 1.6.2.1.b). Exciton luminescence ---------------------------------- 15 1.6.2.1c). Cross luminescence -------------------------------------- 16 1.6.2.2. Extrinsic Luminescence ---------------------------------------- 16 1.6.2.2a). Unlocalised Type---------------------------------------- 16 1.6.2.2b). Localised Type ------------------------------------------- 17 1.7. II-VI Semiconductors ------------------------------------------------------------- 17 1.8. Zinc Sulfide (ZnS) ------------------------------------------------------------------ 18 1.9. Review of Literature --------------------------------------------------------------- 19 1.10. Biological Applications of Semiconductor nanomaterials ------------------- 23 1.11. Biological applications of ZnS --------------------------------------------------- 25 1.12. Motivation of the thesis and statement of research problem ---------------- 27 Objectives of the thesis --------------------------------------------------------------------- 28 2. Synthesis methods and characterization tools ------------------------------------- 31 2.1. Introduction -------------------------------------------------------------------------- 31 2.2. Methods of synthesis of nanomaterials ----------------------------------------- 32 2.2.1. Top-down approach --------------------------------------------------------- 32 2.2.2. Bottom-up approach -------------------------------------------------------- 32 2.3. Hydrothermal Method-------------------------------------------------------------- 33 2.3.1. Merits of Hydrothermal/solvothermal synthesis --------------------- 34 2.3.2. Hydrothermal Apparatus ------------------------------------------------- 35 2.3.2a. Hydrothermal oven or furnace -------------------------------------- 35 2.3.2b. Autoclave --------------------------------------------------------------- 36 2.3.2c. Teflon lined beakers --------------------------------------------------- 36 2.4. Solvo-hydrothermal (S-H) Method ----------------------------------------------- 37