| Popis: |
Emission characteristics under reverse bias of organic EL devices were investigated. We used trihexyl[tetradecyl]phosphoniumbis[trifluoromethylsulfonyl]amide (P66614TFSI) as an ionic liquid to improve the properties of the devices. Poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) as a light emitting polymer and P66614TFSI were dissolved in chloroform and then spin-coated on indium tin oxide (ITO) glass substrates. The devices without P66614TFSI showed almost no flow of electrical current and no light emission until the voltage of 30V, because of the inconsistency of the energy diagrams between the MEH-PPV and the electrodes. On the other hand, the devices with P66614TFSI exhibited a considerable increase in both current density and luminance and a decrease of onset voltage (7V), even without the additional stacking of carrier injection and transport layers. Moreover, the devices with P66614TFSI showed significant flow of electrical current and light emission ever under reverse bias. |
