TY - JOUR
T1 - The role of transition metal oxides in chargegeneration layers for stacked organic light-emitting diodes
AU - Hamwi, Sami
AU - Meyer, Jens
AU - Kröger, Michael
AU - Winkler, Thomas
AU - Witte, Marco
AU - Riedl, Thomas
AU - Kahn, Antoine
AU - Kowalsky, Wolfgang
PY - 2010/6/9
Y1 - 2010/6/9
N2 -
The mechanism of charge generation in transition metal oxide (TMO)-based charge-generation layers (CGL) used in stacked organic light-emitting diodes (OLEDs) is reported upon. An interconnecting unit between two vertically stacked OLEDs, consisting of an abrupt heterointerface between a Cs
2
CO
3
doped 4,7-diphenyl-1,10-phenanthroline layer and a WO
3
film is investigated. Minimum thicknesses are determined for these layers to allow for simultaneous operation of both sub-OLEDs in the stacked device. Luminance - current density - voltage measurements, angular dependent spectral emission characteristics, and optical device simulations lead to minimum thicknesses of the n-type doped layer and the TMO layer of 5 and 2.5 nm, respectively. Using data on interface energetic determined by ultraviolet photoelectron and inverse photoemission spectroscopy, it is shown that the actual charge generation occurs between the WO
3
layer and its neighboring hole-transport material, 4, 4', 4'-tris(N-carbazolyl)-triphenyl amine. The role of the adjacent n-type doped electron transport layer is only to facilitate electron injection from the TMO into the adjacent sub-OLED.
AB -
The mechanism of charge generation in transition metal oxide (TMO)-based charge-generation layers (CGL) used in stacked organic light-emitting diodes (OLEDs) is reported upon. An interconnecting unit between two vertically stacked OLEDs, consisting of an abrupt heterointerface between a Cs
2
CO
3
doped 4,7-diphenyl-1,10-phenanthroline layer and a WO
3
film is investigated. Minimum thicknesses are determined for these layers to allow for simultaneous operation of both sub-OLEDs in the stacked device. Luminance - current density - voltage measurements, angular dependent spectral emission characteristics, and optical device simulations lead to minimum thicknesses of the n-type doped layer and the TMO layer of 5 and 2.5 nm, respectively. Using data on interface energetic determined by ultraviolet photoelectron and inverse photoemission spectroscopy, it is shown that the actual charge generation occurs between the WO
3
layer and its neighboring hole-transport material, 4, 4', 4'-tris(N-carbazolyl)-triphenyl amine. The role of the adjacent n-type doped electron transport layer is only to facilitate electron injection from the TMO into the adjacent sub-OLED.
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U2 - 10.1002/adfm.201000301
DO - 10.1002/adfm.201000301
M3 - Article
AN - SCOPUS:77952975311
SN - 1616-301X
VL - 20
SP - 1762
EP - 1766
JO - Advanced Functional Materials
JF - Advanced Functional Materials
IS - 11
ER -