Current density-voltage and luminance-voltage characteristics (upper inset) of OLEDs with standard functional layer structure and different cathodes: Al (dots), LiF/Al (squares), and (triangles). The device structure is PEDOT:PSS/-NPD (50 nm)/ (50 nm)/cathode (100 nm). In the lower inset the associated lifetime data are shown for devices operated at .
(a) characteristics of electron-only devices with a Ca anode (60 nm), an layer (200 nm), and three different cathodes: Al (dots), LiF/Al (squares), and (triangles). The and LiF interlayer thicknesses are 7 Å, respectively, the Al layer is 100 nm thick. (b) From characteristics of electron-only devices extracted current density at 20 V. In this series the thickness is varied between 0 and 4 nm (squares). For comparison, the accordant values for a congenerous control device with LiF/Al cathode (triangle) are given. In the inset the schematic potential drop is given for devices with and without an interlayer accounting for the different ratios of the dielectric constants of interlayer and semiconductor.
characteristics of electron-only devices in regular and inverse device configuration. (a) filled squares: Ca (60 nm)/ (200 nm)/ (7 Å)/Al (100 nm). (b) open squares: Al (40 nm)/ (7 Å)/ (200 nm)/Ca (20 nm)/Al (100 nm). (c) filled dots: Ca (60 nm)/ (200 nm)/Al (100 nm). (d) open dots: Al (40 nm)/ (7 Å)/ (200 nm)/Ca (20 nm)/Al (100 nm).
Measured and thickness corrected absorption spectra of the pure (triangles down) and (triangles up) layers and of coevaporated layers with a 4.6% (squares) and a 28% (dots) content. With dashed dotted (-.-.-) and dashed (---) lines the respective calculated absorption spectra for the coevaporated layers are shown.
Current density-voltage and luminance-voltage characteristics of devices with a pure layer (dots) and with coevaporated layers with different contents (4.6% triangles, 28% squares). In the inset the capacitance-voltage characteristic of the coevaporated device with 28% content is exemplarily depicted. PEDOT:PSS and Al are employed as anode and cathode, respectively.
Work function development of an Al layer with an increasing layer thickness deposited on top.
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