Quantum dot-dye hybrid systems for energy transfer applications [Elektronische Ressource] / Ting Ren

Ren

Informations

• Publié par: johannes_gutenberg-universitat_mainz
• Publié le: 01 janvier 2010
• Nombre de lectures: 11
• Langue: English
• Poids de l'ouvrage: 45 Mo

Extrait

Quantum Dot-Dye Hybrid Systems
for Energy Transfer Applications




Dissertation
zur Erlangung des Grades
„Doktor der Naturwissenschaften“
In Promotionsfach Chemie


am Fachbereich Chemie, Pharamazie und Geowissenschaften
der Johannes Gutenberg-Universität Mainz



Ting Ren
geb. in Shanghai, P.R. China

Mainz, 2010

Table of Contents

1 Introduction............................................................................................................. 1
2 Theoretical background ......................................................................................... 6
2.1 Quantum dot properties .................................................................................... 6
2.1.1 Bulk semiconductors................................................................................. 6
2.1.2 Quantum dots............................................................................................ 7
2.1.3 Core-shell quantum dots ......................................................................... 11
2.2 Fluorescence resonance energy transfer ......................................................... 17
2.2.1 Characteristics of FRET.......................................................................... 17
2.2.2 Principles of FRET ................................................................................. 18
2.2.3 Measurement of FRET............................................................................ 20
2.3 Energy transfer with quantum dots................................................................. 23
2.3.1 Energy transfer between quantum dots................................................... 23
2.3.1.1 Energy transfer in thin solid film containing quantum dots ................23
2.3.1.2 Energy transfer in layered assemblies of quantum dots ......................24
2.3.1.3 Energy transfer in solution-based complexes containing quantum
dots.......................................................................................................26
2.3.2 Energy transfer from quantum dots to organic dye molecules ............... 27
2.3.2.1 Energy transfer in quantum dot-dye mixtures .....................................27
2.3.2.2 Energy transfer in polymer-mediated quantum dot-dye complexes....29
2.3.2.3 Energy transfer in biomolecule-mediated quantum dot-dye
complexes ............................................................................................30
2.3.3 Energy transfer from quantum dots to metal nanoparticles.................... 32
3 Materials and methods ......................................................................................... 34
3.1 Materials ......................................................................................................... 34
3.2 Synthesis methods........................................................................................... 38
3.2.1 CdSe/CdS/ZnS core-shell quantum dots................................................. 38
3.2.2 Quantum dot hybrid systems .................................................................. 40
3.2.2.1 Quantum dot - silica hybrids................................................................40
3.2.2.2 Quantum dot - silica - dye hybrids.......................................................... 42
3.2.2.3 Quantum dot - dye hybrids ..................................................................... 42
iii3.3 Characterization techniques ............................................................................44
3.3.1 Absorption spectroscopy.........................................................................44
3.3.2 Steady-state fluorescence spectroscopy ..................................................44
3.3.3 Transmission electron microscopy..........................................................45
3.3.4 Fluorescence lifetime spectroscopy ........................................................46
3.3.5 Dynamic light scattering .........................................................................46
Results and Discussion
4 Quantum dot - silica hybrid system.....................................................................48
4.1 Introduction .....................................................................................................48
4.2 Silica - quantum dot - silica architecture.........................................................50
4.2.1 Experimental procedure ..........................................................................50
4.2.2 Results and discussion.............................................................................51
4.2.2.1 TEM characterization.......................................................................... 51
4.2.2.2 Optical properties ................................................................................ 54
4.2.2.3 Influence of silica core size................................................................. 55
4.2.2.4 Thickness control ................................................................................ 57
4.3 Quantum dot - silica architecture: silica coated quantum dots........................59
4.3.1 Experimental procedure ..........................................................................59
4.3.2 Results and discussion.............................................................................60
4.3.2.1 TEM characterization.......................................................................... 60
4.3.2.2 Optical properties ................................................................................ 60
4.3.2.3 Growth process of QD-silica spheres.................................................. 61
4.3.2.4 Control of silica shell thickness .......................................................... 64
4.4 Conclusion.......................................................................................................72
5 Quantum dot - silica - dye hybrid system ...........................................................73
5.1 Introduction .....................................................................................................73
5.2 Experimental procedure ..................................................................................74
5.3 Results and discussion.....................................................................................77
5.3.1 TEM characterization..............................................................................77
5.3.1.1 CdSe/CdS/ZnS QDs ............................................................................ 78
5.3.1.2 Silica cores .......................................................................................... 78
5.3.1.3 Silica-dye (silica-core - dye-shell) nanospheres.................................. 78
5.3.1.4 QD-silica-dye hybrid nanoparticles .................................................... 78
iv 5.3.2 Fluorescence of silica-dye particles........................................................ 79
5.3.3 Fluorescence of QD-silica-dye particles................................................. 81
5.3.3.1 Optical properties of QD-silica-dye particles ......................................81
5.3.3.2 Monte-Carlo Simulations.....................................................................84
5.3.3.3 Experimental determination of the amount of QDs adsorbed onto
pure silica and onto silica-dye particles...............................................87
5.3.3.4 Attraction between QD and Texas Red molecules ..............................89
5.4 Conclusion ...................................................................................................... 91
6 Quantum dot - dye hybrid system....................................................................... 92
6.1 Introduction..................................................................................................... 92
6.2 Quantum dot - dye hybrids in non-aqueous solution...................................... 94
6.2.1 Experimental procedure.......................................................................... 94
6.2.2 Results and discussion ............................................................................ 95
6.2.2.1 Characterization of QD-dye complexes...............................................95
6.2.2.2 Study of binding mechanism and reaction conditions.........................98
6.2.2.3 Stability of QD-dye complexes..........................................................106
6.2.2.4 Energy transfer in QD-dye complexes...............................................108
6.2.2.5 Distance dependence of energy transfer in QD-dye complexes ........113
6.3 Quantum dot - dye hybrids in aqueous solution ........................................... 123
6.3.1 Experimental procedure........................................................................ 123
6.3.2 Results and discussion .......................................................................... 124
6.3.2.1 Phase transfer method........................................................................124
6.3.2.2 “Refluxing” method...........................................................................126
6.4 Quantum dot assemblies ............................................................................... 135
6.4.1 Experimental procedure......................................................