Highly Efficient Green Organic Light Emitting Diode with a Novel Solution Processable Iridium Complex Emitter

• Main Authors: Li, Chieh-Ju, 李倢如
• Other Authors: 周卓煇
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/15153884505259559726

碩士 === 國立清華大學 === 材料科學工程學系 === 101 === Green light is both the major component for the fabrication of multi-band composing white light and the key color of the typical RGB full-color technology. Moreover, it is also the most critical composition for the highly efficient white light since luminous sensitivity of human eyes is the highest with green light. Therefore, innovatively developing a high-efficiency green device is quite crucial. For the organic light emitting diodes (OLEDs), on the other hand, solution process is a promising technology to realize roll-to-roll production and to achieve low-cost probability. We hence study in this thesis the fabrication of a highly efficient green OLED device with a solution-processable emissive layer. We demonstrate a high-efficiency green OLED with a solution-processed emissive layer composing a novel green light emitting iridium complex, bis[5-methyl-8-trifluoromethyl-5H-benzo(c)(1,5) aphthyridin-6-one]iridium (pyrazinecarboxylate). By coupling with a proper host, the green device shows at 1,000 cd m-2 an external quantum efficiency of 23.8%, current efficiency of 95.6 cd A-1, and efficacy of 60.8 lm W-1, the highest among all reported solution-processed OLEDs. The high efficiency may be attributed to the host possessing a zero electron injection barrier, resulting in a more balanced carrier-injection. Besides, the paired host and guest energy-levels allow excitons to generate on the guest predominantly at low voltage, but with increasing excitons generating on the host with the increasing voltage.