In:
Japanese Journal of Applied Physics, IOP Publishing, Vol. 49, No. 8S1 ( 2010-08-01), p. 08JG04-
Abstract:
We demonstrated that single-layered red phosphorescent organic light-emitting diodes (OLEDs) can have high a efficiency without carrier transport and injection layers. This high efficiency is caused by the direct injection of carriers from electrodes into a dopant, bis(2-phenylquinoline) iridium(III) (acetylacetonate) [Ir(ppy) 2 (acac)]. This mechanism is proved by analyzing the single-layered devices with various hosts, 4,4'- N , N '-dicarbazole-biphenyl (CBP), 9-phenyl-3-[4-(1-phenyl-1 H -benzo[ d ]imidazol-2-yl)phenyl] -9 H -carbazole (LPGH 114), 9-(naphthalen-2-yl)-3-[4-(1-phenyl-1 H -benzo[ d ]imidazol-2-yl)phenyl] -9 H -carbazole (LPGH 124), and 9-phenyl-3,6-bis[4-(1-phenyl-1 H -benzo[ d ]imidazol-2-yl)phenyl] -9 H -carbazole (LPGH 153). Among the devices, the single-layered device with LPGH 153 shows a luminous efficiency, a power efficiency, and a quantum efficiency of 9.3 cd/A, 5.2 lm/W, and 6.2%, respectively. The single-layered device with CBP was compared with a multilayered device with CBP. As a result, the single-layered device shows a reduced operating voltage, an enhanced roll-off efficiency, and a pure emitting color in comparison with the multilayered device owing to the direct injection of carriers into a dopant and the suppression of exciplex formation.
Type of Medium:
Online Resource
ISSN:
0021-4922
,
1347-4065
DOI:
10.1143/JJAP.49.08JG04
Language:
Unknown
Publisher:
IOP Publishing
Publication Date:
2010
detail.hit.zdb_id:
218223-3
detail.hit.zdb_id:
2006801-3
Permalink