Full text loading...
The proposed energy level diagram of the white organic light emitting Device 1. Gaps are inserted between each layer to indicate the possible existence of interface dipole layers of undetermined magnitude. Numbers represent energies in eV. The highest occupied molecular orbital energies are obtained via ultraviolet photoemission spectroscopy measurements, and the lowest unoccupied molecular orbital energies are estimated from the optical gaps.
Reflection spectra of various cathodes employed. Squares: Al (1000 Å)/Ni (50 Å) after UV-ozone treatment (Devices 1 and 3). Open circles: a similar cathode to Device 1, but with an untreated surface (Device 2). Open squares: as-deposited Al (500 Å). Inset: Transmission spectra of sputtered ITO used in the cathodes of Devices 1 and 3, and glass pre-coated with commercial ITO used as the anode in Device 2.
(a) The external quantum and luminous power efficiencies of all devices studied as functions of current density. (b) Current density vs. voltage characteristics of devices in (a), including Device 4 with a structure similar to Device 2 (see text), except with an Al (1000 Å)/Ni (50 Å) instead of ITO.
Angular dependence of EL spectra of a top-emitting WOLED, Device 1, at a current density of . The CIE co-ordinates are , , and at 0°, 30° and 60°, respectively. The curves are vertically offset for clarity. Similar results are obtained for the bottom-emitting Device 2.
Performance characteristics of the WOLEDs.
Article metrics loading...