|Title||Deep blue/ultraviolet microcavity OLEDs based on solution-processed PVK:CBP blends|
|Publication Type||Journal Article|
|Year of Publication||2015|
|Authors||Hellerich, ES, Manna, E, Heise, R, Biswas, R, Shinar, R, Shinar, J|
|Type of Article||Article|
|Keywords||ab initio, arrays, chip, combinatorial fabrication, derivatives, diodes, efficiency, light-emitting device, oxygen, planar, platform, Polymer/small molecule mixed emission layer, PVK:CBP OLED, sensors, simulations of OLED EL spectra, UV-to-blue microcavity OLED arrays, UV-to-blue OLED arrays|
-bis(9-carbazolyl)-biphenyl (CBP), whose ITO-based devices show a broad electroluminescence (EL) in the wavelength range of interest. This 373-469 nm band expands the 493-640 nm range previously attained with mu cOLEDs into the desired deep blue-to-near UV range. Moreover, the current work highlights interesting characteristics of the complexity of mixed EML emission in combinatorial 2-d mu cOLED arrays of the structure 40 nm Ag/x nm MoOx/similar to 30 nm PVK: CBP (3: 1 weight ratio)/y nm 4,7-diphenyl-1,10-phenanthroline (BPhen)/1 nm LiF/100 nm Al, where x = 5, 10, 15, and 20 nm and y = 10, 15, 20, and 30 nm. In the short wavelength mu c devices, only CBP emission was observed, while in the long wavelength mu c devices the emission from both PVK and CBP was evident. To understand this behavior simulations based on the scattering matrix method, were performed. The source profile of the EML was extracted from the measured EL of ITO-based devices. The calculated mu c spectra indeed indicated that in the thinner, short wavelength devices the emission is primarily from CBP; in the thicker devices both CBP and PVK contribute to the EL. This situation is due to the effect of the optical cavity length on the relative contributions of PVK and CBP EL through a change in the wavelength-dependent emission rate, which was not suggested previously. Structural analysis of the EML and the preceding MoOx layer complemented the data analysis. (C) 2015 Elsevier B.V. All rights reserved.
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