Effect of Hole Injection Layer Modification on Blue Organic Light-Emitting Diode

• Main Authors: LO, CHENG-CHIEH, 羅正傑
• Other Authors: LEE, JIA-REN
• Format: Others
• Language: zh-TW
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/vhr7jw

碩士 === 國立高雄師範大學 === 物理學系 === 107 === Organic light-emitting diode has played a key role in display technology for new generation electronic products. It has been successfully implemented for mobile phones and TVs. With wet process technology, OLED devices can be fabricated in large areas and reduce cost. On the other hand, blue light plays an important role in full-color displays with high quality. So it is very important to improve the efficiency of a wet-processed blue OLED. In this study, the modification of the hole injection layer (HIL) was utilized to enhance the performance of the sky blue OLED. The modification was done via adding solvents such as deionized water, acetone and anhydrous alcohol into the hole injection material poly(3,4-ethylene dioxythiophene) polystyrene sulfonic acid (PEDOT: PSS). HIL was spin-coated on the substrate to fabricate blue OLED device. The results show that, PEDOT: PSS modified with 30% acetone has the best device performance. The power efficacy of the device increased from 17.2 to 24.2 lm/W, with an increment of 41%; The current efficacy improved from 24.6 to 30.5 cd/A, with an increment of 24 %. Besides, the external quantum efficiency increased from 10.8 to 13.1 %, with an increment of 21% at 100 cd/m2. The maximum luminance has also increased from 14,590 to 18,190 cd/m2. The improvement of device performance can be attributed to the following characteristics of the modified hole injection layer: (1)Increase of the conductivity results in more current density. (2)The change of carrier mobility increases the hole injection ability. (3)Decrease of the refractive index can effectively improve the light extraction efficiency. (4) Increase of the transmittance gets higher light out coupling.