Three subjects on the organic light-emitting diodes (OLEDs) have been studied. First, We inserted a NPB¡GAlq3 mixed layer between these two NPB and Alq3 layers to decrease the holes mobility and improve the combined efficiency between the holes and electrons. After inserting the NPB¡GAlq3 layer, the current density of the device( ITO/ MTDATA¡]5 nm¡^/ NPB¡]60-Y¡^nm¡^/NPB¡GAlq3 (Z wt%)(Y nm) / Alq3¡]60 nm¡^/ LiF(0.7 nm)/ Al(180 nm)) is decreased obviously. This result suggests that NPB¡GAlq3 layer could delay the holes mobility. The optimum concentration in our device is 30 wt% while the total thickness is 30nm. Then we combined NPB and Rubrene to obtaine white emission and fabricate a white organic light emitting diode (WOLED). The structure of WOLEDs is ITO/ MTDATA/ NPB/ NPB:Rubrene/ TPBI/ LiF/ Al. By change the concentration of NPB:Rubrene layer, the WOLED can emit white light. We can get the maximum luminance efficiency of 9.0 cd/A at 20.8mA/cm2 with 1 wt%. And the device emit greenish-white.
In order to get higher efficiency and pure light WOLED, we use the grading structure to prepare OLED. The structures are device A: ITO/ MTDATA(5nm)/ NPB(10nm)/ NPB:Rubrene1%(25nm)/ NPB:Rubrene 0.5%(25nm)/ TPBI(60nm)/ LiF(0.7nm)/Al (180nm); device B: ITO/ MTDATA(5nm)/NPB(10nm)/NPB:Rubrene2%(17nm)/ NPB:Rubrene1% (17nm)/NPB:Rubrene0.5%(17nm)/TPBI(60nm)/ LiF(0.7nm)/ Al (180nm)
We get the maximum luminance of 17270 cd/m2 and 24280 cd/m2 , respectively and the optimum efficiency of 16.1 cd/A and 18.5 cd/A, respectively. The CIE coordinate of the device is x=0.35, y=0.36, which is identical to white light.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0213107-041951 |
| Date | 13 February 2007 |
| Creators | Tseng, Ching-huei |
| Contributors | none, Herng-yih Ueng, none, none, none, none |
| 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-0213107-041951 |
| Rights | not_available, Copyright information available at source archive |
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