(A) Study on all solution processed organic light emitting diodes

다국어 초록 (Multilingual Abstract)

We have studied OLED device fabrication using solution processes. As we fabricated the green phosphorescent OLED device for the solution process, we could improve the current efficiency of the device by about 15% from 61.6 cd/A to 72.7 cd/A by optimizing the interface between the cross-linkable HTL and EML. In addition, we found that the efficiency of blue phosphorescent devices increased when we did not introduce cross-linkable HTLs, while fabricating Blue phosphorescent OLED devices for solution processes. Finally, OLED devices were fabricated to utilize the all solution process. By introducing the inverted structure, GraHIL, and CGL, we were able to fabricate a Yellow device with stability and maximum current efficiency of 17.5 cd/A.

목차 (Table of Contents)

• 1. Introduction 1
• 1.1. OLEDs 1
• 1.2 Motivation and theme of the works 3
• 1.3 Gradient hole injection layers (GraHIL) 4
• 2. Experimental method 6
• 2.1. Device fabrication 6
• 2.1.1. Substrate cleaning 6
• 2.1.2. Organic / metal layer evaporation 6
• 2.1.3. Encapsulation 7
• 2.2. Measurement and evaluation 7
• 2.2.1. Measurement of layer thickness 7
• 2.2.2. Evaluation of device characteristics 8
• 3. Results and Discussion 9
• 3.1. Solution processed green phosphorescent organic emitting diodes 9
• 3.1.1. Materials 9
• 3.1.2. Device fabrication process 11
• 3.1.3. Importance of solubility orthogonality 14
• 3.1.4. Interface mixing effect according to the degree of cross-linking in solution processed OLED 18
• 3.2. Solution processed blue phosphorescent organic emitting diodes 23
• 3.2.1. Materials 23
• 3.2.2. Device fabrication process 26
• 3.2.3. Device performance 29
• 3.3. All solution processed yellow organic emitting diodes 34
• 3.3.1. Materials 34
• 3.3.2. Device fabrication process 36
• 3.3.3. Orthogonality and WO3 for charge generation layer 39
• 3.3.4. Device performance of yellow OLED 40
• 4. Conclusion 48
• References 49
• Abstract 54