Recently, ¡§Pyrene¡¨ is a well-known substitutive group because the rigid structure and hole-injection ability of pyrene units can improve the thermal and electronic properties of blue OLED materials. The aromatic ring of pyrene not only improves the thermal and hole-injection ability of derivatives, but also provides high photoluminescence (PL) efficiency and high carrier mobility. Through these characteristics we can understand that the electron-rich pyrene derivatives can enhance the properties of OLED device.
In this study, we developed low-molecular-weight structures with spiro-type molecules based on 9,9-spirobifluorene and fabricated the OLED device with the structure of ITO(170 nm)/PEDOT:PSS(50 nm)/PVK:TPSBF (40%)(90 mm)/BPhen (30 nm)/ LiF(1 nm)/Al(200 nm). It exhibited a maximum luminance at 500 mA/cm2 of 4130 cd/m2 with the Commission Internationale de l'Eclairage (CIE) of (0.16 , 0.16), and the maximum current and power efficiency were 1.9 cd/A and 0.9 lm/W, respectively. We concluded that TPSBF has good emission efficiency according to device performances.
The PL maximum of the thick film of TPSBF, prepared by vacuum vapor deposition appears broadband spectrum, that resulted from the aggregation of the pyrene moieties. From Atomatic Force Microscopy (AFM) results, we propose three emission mechanisms.
1. Intramolecular spectrum ¡÷ 450 nm
2. Molecular aggregation spectrum ¡÷ 500 nm
3. Longer conjugation spectrum of intermolecular ¡÷ 550 nm
We could fabricate the organic white light emitting device with a single and thicker emitting layer TPSBF and the more broadband emitting spectrum can be obtained.
Finally, we fabricated the organic white light emitting device with a structure of ITO(170 nm)/2T-NATA(15 nm)/NPB(65 nm)/TPSBF(50 nm)/Alq3(30 nm)/LiF(0.8 nm)/Al(200 nm). It exhibited a maximum luminance at 1300 mA/cm2 of 57680 cd/m2, the maximum current and power efficiency were 6.51 cd/A and 4.07 lm/W, respectively, and with good CIE coordinate of (0.29 , 0.36).
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0824111-131708 |
| Date | 24 August 2011 |
| Creators | Chao, Chun-ming |
| Contributors | Shun-wei Liu, Yu-kai Han, Ping-tsung Huang, Chih-chien Lee, Mei-ying Chang |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | Cholon |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0824111-131708 |
| Rights | user_define, Copyright information available at source archive |
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