Synthesis of a Series of A-D-A type Conjugated Oligomers and their Applications of Organic Solar Cells
- Abstract
- A series of acceptor-donor-acceptor (A-D-A) type oligomer based on benzothiadiazole (BT) and a series of central unit such as carbazole (Cz), 2,7-bis-[5-(7-methyl-benzo[1,2,5]thiadiazol-4-yl)-thiophen-2-yl]-9-(2-octyl-dodecyl)-9H-carbazole (Cz-BT); 2,7-bis-[5'-(7-methyl-benzo[1,2,5]thiadiazol-4-yl)-[2,2']bithiophenyl-5-yl]-9-(2-octyl-dodecyl)-9H-carbazole (CzT-BT) and 2,7-Bis(5-{7-2[-(4-decyloxy-phenyl)-vinyl]-benzo[1,2,5]thiadiazol-4-yl}-thiophen-2-yl)-9-(2-octyl-dodecyl)-9H-carbazole (CzBT-DP), phenothiazine, 3,7-bis-[5-(7-methyl-benzo[1,2,5]thiadiazol-4-yl)-thiophen-2-yl]-10-(2-octyl-dodecyl)-10H-phenothiazine (PTBT), and benzodithiophene, 4,8-Bis-(2-ethyl-octyloxy)-2,6-benzonitrile-1,5-dithia-s-indacene (BDT-B); 4,8-Bis-(2-ethyl-octyloxy)-2,6-pyridine-2-carbonitrile-1,5-dithia-s-indacene (BDT-P); 4,8-Bis-(2-ethyl-octyloxy)-2,6-2-benzylidene-malononitrile-1,5-dithia-s-indacene (BDT-M), are synthesized by the Suzuki coupling and Stille coupling reaction to investigate the effect of combination between strong electron donor and strong electron acceptor properties of conjugated oligomer. In Cz-BT, CzT-BT, CzBT-DP and PTBT, thiophene ring was added as a -bridge to extend the effective of conjugation length. Optical, electrical and thermal properties and photovoltaic performances of those oligomers is systematically investigated. UV-Vis absorption spectra and cyclic voltammetry (CV) reveal that HOMO/LUMO level of oligomers range from -6.21~(-5.19) eV for HOMO level and -3.95~(-3.18) eV for LUMO level with optical band gap 1.99 – 2.29 eV, respectively. The HOMO energies of those oligomers were calculated from the measured onset potential of oxidation by assuming the energy level of ferrocene (Fc) as -4.8 eV by CV. Addition of thiophene affect the HOMO level which make Cz-BT, CzT-BT, CzBT-DP and PTBT has high lying HOMO level. Due to higher LUMO energy values above 0.3 eV than PC71BM, those oligomers could be applied to BHJ OSCs as the donor [1]. Inverted-type organic solar cells (OSCs) with a configuration of ITO/ZnO/oligomer:PC71BM/MoO3/Al are fabricated. Maximum power conversion efficiency (PCE) of the OSCs based on small molecules is showed up to 1.58%, the Voc, Jsc, and FF were 1.04 ~ 1.06 V, 2.52 ~ 3.46 mA/cm2, and 37.0 ~ 47.3% from the devices based Cz-BT. Among the devices, the best PCE of the device showed at the Cz-BT:PC71BM ratio of a 3:3.
- Issued Date
- 2017
- Awarded Date
- 2017. 2
- Type
- Dissertation
- Keyword
- Organic Solar Cell
- Publisher
- 부경대학교 대학원
- Affiliation
- 부경대학교 대학원
- Department
- 대학원 고분자공학과
- Advisor
- 김주현
- Table Of Contents
- Chapter I. Introduction 1
I-1. Organic Solar Cells (OSCs) 1
I-2. Basic Principles of OSCs 3
I-2.1. Absorption of light and generation of excitons 3
I-2.2. Diffusion of the excitons 4
I-2.3. Dissociation of the excitons with generation of charge 5
I-2.4. Charge transport and charge collection 5
I-3. Structure of Organic Solar Cells 6
I-4. Solar Cells Materials 10
I-4.1. Polymer Solar Cells (PSCs) 10
I-4.2. Small Molecule Organic Solar Cells (SMOSCs) 14
I-4.2.a. Small molecular donors 16
I-4.2.b. Small molecular acceptors 17
I-5. Performance Parameter of Solar Cells 22
I-5.1. Short Circuit Current of Solar Cell (Jsc) 23
I-5.2. Open Circuit Voltage (Voc) 23
I-5.3. Fill Factor (FF) 24
I-5.4. Incident Photon to Current Efficiency (IPCE) 25
I-5.5. Power Conversion Efficiency (IPCE) 26
I-6. Factors affect the efficiency of OSCs 26
I-6.1. Band gap and energy level 26
I-6.2. Thickness of active layer and solvent 29
I-6.3. Ratio between donor and acceptor 31
I-6.4. Thermal annealing 32
I-6.5. Solvent annealing 32
I-6.6. Processing additives 33
Chapter II. A-D-A type Conjugated Oligomers Based on Benzothiadiazole and their Photovoltaic Applications 36
II-1. Introduction 36
II-2. Experimental Section 39
II-2.1. Material 39
II-2.2. Synthesis 39
II-2.2.1. General procedure for the Stille coupling reaction 39
II-2.2.2. Synthesis of 4-Methyl-7-thiophen-2-yl-benzo[1,2,5]thiadiazole (2) 40
II-2.2.3. Synthesis of 4-(5-Bromo-thiophen-2-yl)-7-methyl-benzo[1,2,5]thiadiazole (3) 41
II-2.2.4. Synthesis of 4-[2,2']Bithiophenyl-5-yl-7-methyl-benzo[1,2,5]thiadiazole (4) 42
II-2.2.5. Synthesis of 4-(5'-Bromo-[2,2']bithiophenyl-5-yl)-7-methyl-benzo[1,2,5]thiadiazole (5) 43
II-2.2.6. Synthesis of 9-(2-Octyl-dodecyl)-2,7-bis-(4,4,5,5-tetramethyl-[1,3]dioxolan-2-yl)-9H-carbazole (6) 44
II-2.2.7. General procedure for the Suzuki coupling reaction 44
II-2.2.8. Synthesis of 2,7-Bis-[5-(7-methyl-benzo[1,2,5]thiadiazol-4-yl)-thiophen-2-yl]-9-(2-octyl-dodecyl)-9H-carbazole (Cz-BT) 45
II-2.2.9. Synthesis of 2,7-Bis-[5'-(7-methyl-benzo[1,2,5]thiadiazol-4-yl)-[2,2']bithiophenyl-5-yl]-9-(2-octyl-dodecyl)-9H-carbazole (CzT-BT) 46
II-2.3. Fabrication of PSCs 47
II-2.4. Measurement 48
II-3. Result and Discussion 49
II-3.1. Synthesis of CzBT and CzTBT 49
II-3.2. Theoritical Calculation 51
II-3.3. Optical and electrochemical properties 52
II-3.4. Photovoltaic Properties 56
II-4. Conclusion 64
Chapter III. A--D--A Type Oligomer Based on Carbazole Derivative for Solution Processed Organic Solar Cells 65
III-1. Introduction 65
III-2. Experimental Section 67
III-2.1. Material 67
III-2.2. Synthesis 67
III-2.2.1. Synthesis of 4-Bromomethyl-7-(5-bromo-thiophen-2-yl-benzo[1,2,5]thiadiazole (2) 67
III-2.2.2. Synthesis of [7-(5-Bromo-thiophen-2-yl)-benzo[1,2,5]thiadiazol-4-ylmethyl]-tryphenyl-phosphonium; bromide (3) 68
III-2.2.3. Synthesis of 4-Decyloxy-benzaldehyde (4) 69
III-2.2.4. Synthesis of 4-(5-Bromo-thiophen-2-yl)-7-[2-(4-decyloxy-phenyl)-vinyl]-benzo[1,2,5]thiadiazole (5) 70
III-2.2.5. Synthesis of 2,7-Bis-(5-{7-[2-(4-decyloxy-phenyl)-vinyl]-benzo[1,2,5]thiadiazol-4-yl}-thiophen-2-yl)-9-(2-octyl-dodecyl)-9H-carbazole (6) 71
III-2.3. Fabrication of PSCs 72
III-2.4. Measurement 73
III-3. Result and Discussion 74
III-3.1. Synthesis and Characterization 74
III-3.2. Theoretical Calculation 75
III-3.3. Optical Properties 77
III-3.4. Electrochemical Properties 78
III-3.5. Photovoltaic Properties 80
III-4. Conclusion 82
Chapter IV. Synthesis and Characterization Conjugated Oligomer based on Phenothiazine Derivative 84
IV-1. Introduction 84
IV-2. Experimental Section 86
IV-2.1. Material 86
IV-2.2. Synthesis 86
IV-2.2.1. Synthesis of 4-Methyl-7-thiophen-2-yl-benzo[1,2,5]thiadiazole (2) 86
IV-2.2.2. Synthesis of 4-(5-Bromo-thiophen-2-yl)-7-methyl-benzo[1,2,5]thiadiazole (3) 87
IV-2.2.3. Synthesis of 3,7-Bis-[5-(7-methyl-benzo[1,2,5]thiadiazol-4-yl)-tetrahydro-thiophen-2-yl]-10-(2-octyl-dodecyl)-10H-phenothiazine) (PTBT) 88
IV-2.3. Fabrication of PSCs 90
IV-2.4. Measurement 90
IV-3. Result and Discussion 92
IV-3.1. Synthesis and Characterization 92
IV-3.2. Theoretical Calculation 93
IV-3.3. Optical Properties 94
IV-3.4. Electrochemical Properties 95
IV-3.5. Photovoltaic Properties 97
IV-4. Conclusion 100
Chapter V. Synthesis of A-D-A Type Oligomer Based on Benzodithiophene Derivatives 101
V-1. Introduction 101
V-2. Experimental Section 103
V-2.1. Material 103
V-2.2. Synthesis 104
V-2.2.1. General procedure of the stille coupling reaction 104
V-2.2.2. Synthesis of 2,6-benzonitrile-4,8-bis((2-ethylhexyl)oxy)benzo[1,2-b:4,5-b']dithiophene) (BDT-B) (3) 104
V-2.2.3. Synthesis of 2,6-pyridine-2-carbonitrile-4,8-bis((2-ethylhexyl)oxy)benzo[1,2-b:4,5-b']dithiophene) (BDT-P) (5) 105
V-2.2.4. Synthesis of 2,6-benzylidene-malononitrile-4,8-bis((2-ethylhexyl)oxy)benzo[1,2-b:4,5-b']dithiophene) (BDT-M) (5) 106
V-2.3. Measurement 108
V-3. Result and Discussion 109
V-3.1. Synthesis and Characterization 109
V-3.2. Theoretical Calculation 110
V-3.3. Optical Properties 112
V-3.4. Electrochemical Properties 114
V-4. Conclusion 117
Summary 118
References 119
Acknowledgment 134
- Degree
- Master
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