DGIST Scholar: Novel n-type organic semiconducting materials for high-performance blue phosphorescent OLEDs

Department of Energy Science and Engineering Theses Ph.D.

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Novel n-type organic semiconducting materials for high-performance blue phosphorescent OLEDs

Title: Novel n-type organic semiconducting materials for high-performance blue phosphorescent OLEDs

Alternative Title: 고성능 청색 인광 OLED를 위한 신규 n형 유기 반도체 소재

Author(s): Seokhoon Jang

DGIST Authors: Seokhoon Jang ; Youngu Lee ; Soon Moon Jeong

Advisor: 이윤구

Co-Advisor(s): Soon Moon Jeong

Issued Date: 2021

Awarded Date: 2021/02

Type: Thesis

Subject: Phosphorescent OLEDs, Dibenzo[b,d]furan, Triplet energy, HOMO energy, Hole-blocking, 청색 인광 OLED, 정공저지층, 디벤조퓨란, 삼중항 에너지, 유리전이온도

Table Of Contents: I. INTRODUCTION 1

II. THEORETICAL BACKGROUND
2.1 Organic light-emitting diodes 5
2.1.1 Historical background of EL devices 5
2.1.2 OLED structure and driving mechanism 6
2.1.3 Host-Dopant system and energy transport mechanism 7
2.1.4 Efficiency parameters of OLED 10
2.2 Problems of phosphorescent OLEDs 10
2.2.1 Limitation of conventional electron transport materials 10
2.2.2 Importance of glass transition temperature 12
2.3 Molecualr design stratery for high-performance blue phosphorescent OLEDs 13
2.3.1 n-Type organic semiconducting materials with oxadiazole 13
2.3.2 n-Type organic semiconducting polymers with oxadiazole 18
2.3.3 n-Type organic semiconducting polymers with PMMA and oxadiazole pendant 19
2.3.4 High-performance n-type organic semiconducting materials with oxadiazole 21
2.3.5 n-Type organic semiconducting materials with metal-chelated structure 27
2.3.6 n-Type organic semiconducting materials with pyridine 30
2.3.7 n-Type organic semiconducting materials with branched pyridine 36
2.3.8 n-Type organic semiconducting materials with fluorine and pyridine 39
2.3.9 n-Type organic semiconducting materials with triazine 43
2.3.10 n-Type organic semiconducting materials with silyl group 44
2.3.11 n-Type organic semiconducting materials with pyrimidine group 46
2.4 Reference 51

III. PYRIMIDINE BASED HOLE BLOCKING MATERIALS WITH HIGH TRIPLET ENERGY AND GLASS TRANSITION TEMPERATURE
3.1 Introduction 60
3.2 Nomenclature 62
3.2.1 Acronym 62
3.2.2 Symbol and Greek 63
3.3 Experimental 63
3.3.1 General information 63
3.3.2 Synthesis 64
3.3.2.1 Synthesis of compound 3-1 64
3.3.2.2 Synthesis of compound 3-2 65
3.3.2.3 Synthesis of compound 3-3 66
3.3.2.4 Synthesis of mPyrPPB 67
3.3.2.5 Synthesis of pPPyrPB 68
3.3.3 Device fabrication and analysis 70
3.4 Results and discussion 71
3.4.1 Design and synthesis 71
3.4.2 Thermal properties 72
3.4.3 Photophysical properties 73
3.4.4 Electrochemical properties 75
3.4.5 Quantum chemical simulation 76
3.4.6 Electron transport properties 78
3.4.7 Performance of blue phosphorescent OLEDs 79
3.5 Conclusion 82
3.6 Reference 83

IV. NOVEL HOLE BLOCKING MATERIALS BASED ON 2,6-DISUBSTITUTED DIBENZO[b,d]FURAN AND DIBENZO[b,d]THIOPHENE SEGMENTS
4.1 Introduction 86
4.2 Nomenclature 88
4.2.1 Acronym 88
4.2.2 Symbol and Greek 89
4.3 Experimental 90
4.3.1 General information 90
4.3.2 Synthesis 90
4.3.2.1 Synthesis of compound 4-1 90
4.3.2.2 Synthesis of compound 4-2 92
4.3.2.3 Synthesis of compound 4-3 93
4.3.2.4 Synthesis of compound 4-4 95
4.3.2.5 Synthesis of 26DBFPTPy 96
4.3.2.6 Synthesis of 26DBTPTPy 98
4.3.3 Device fabrication and analysis 99
4.4 Results and discussion 100
4.4.1 Design and synthesis 100
4.4.2 Quantum chemical simulation 101
4.4.3 Thermal properties 103
4.4.4 Photophysical properties 105
4.4.5 Electrochemical properties 106
4.4.6 Electron transport properties 107
4.4.7 Performance of blue phosphorescent OLEDs 108
4.5 Conclusion 112
4.6 Reference 112

V. DIBENZO[b,d]FURAN AND DIBENZO[b,d]THIOPHENE MOLECULAR DIMERS AS HOLE BLOCKING MATERIALS
5.1 Introduction 116
5.2 Nomenclature 118
5.2.1 Acronym 118
5.2.2 Symbol and Greek 119
5.3 Experimental 120
5.3.1 General information 120
5.3.2 Synthesis 120
5.3.2.1 Synthesis of compound 5-1 120
5.3.2.2 Synthesis of compound 5-2 122
5.3.2.3 Synthesis of compound 5-3 123
5.3.2.4 Synthesis of compound 5-4 124
5.3.2.5 Synthesis of compound 5-5 125
5.3.2.6 Synthesis of compound 5-6 126
5.3.2.7 Synthesis of DBF-d-PO 126
5.3.2.8 Synthesis of DBT-d-PO 127
5.3.2.9 Synthesis of DBF-d-Py 128
5.3.2.10 Synthesis of DBT-d-Py 130
5.3.3 Calculation of molecular energy level 131
5.3.4 Device fabrication and analysis 131
5.4 Results and discussion 132
5.4.1 Design and synthesis 132
5.4.2 Quantum chemical simulation 133
5.4.3 Thermal properties 134
5.4.4 Photophysical properties 138
5.4.5 Electrochemical properties 140
5.4.6 Electron transport properties 141
5.4.7 Performance of blue phosphorescent OLEDs 142
5.5 Conclusion 146
5.6 Reference 147

VI. N-TYPE HOST MATERIALS BASED ON NITRILE AND TRIAZINE SUBSTITUTED TRICYCLIC AROMATIC COMPOUNDS
6.1 Introduction 152
6.2 Nomenclature 154
6.2.1 Acronym 154
6.2.2 Symbol and Greek 155
6.3 Experimental 156
6.3.1 General information 156
6.3.2 Synthesis 156
6.3.2.1 Synthesis of compound 6-1 156
6.3.2.2 Synthesis of compound 6-2 158
6.3.2.3 Synthesis of compound 6-3 159
6.3.2.4 Synthesis of compound 6-4 160
6.3.2.5 Synthesis of compound 6-5 162
6.3.2.6 Synthesis of compound 6-6 162
6.3.2.7 Synthesis of 2Trz6CNDBF 163
6.3.2.8 Synthesis of 2Trz6CNDBT 164
6.3.3 Device fabrication and analysis 165
6.4 Results and discussion 165
6.4.1 Design and synthesis 165
6.4.2 Quantum chemical simulation 166
6.4.3 Thermal properties 167
6.4.4 Photophysical properties 168
6.4.5 Electron transport properties 170
6.4.6 Performance of blue TADF OLEDs 171
6.5 Conclusion 175
6.6 Reference 176

VII. SUMMARY 181