TY  - JOUR
A1  - Yang, Xiao Hui
A1  - Jaiser, Frank
A1  - Stiller, Burkhard
A1  - Neher, Dieter
A1  - Galbrecht, Frank
A1  - Scherf, Ullrich
T1  - Efficient polymer electrophosphoreseent devices with interfacial layers
JF  - Advanced functional materials
N2  - It is shown that several polymers can form insoluble interfacial layers on a poly (ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) layer after annealing of the double-layer structure. The thickness of the interlayer is dependent on the characteristics of the underlying PEDOT.PSS and the molecular weight of the polymers. It is further shown that the electronic structures of the interlayer polymers have a significant effect on the properties of red-light-emitting polymer-based electrophosphorescent devices. Upon increasing the highest occupied molecular orbital and lowest unoccupied molecular orbital positions, a significant increase in current density and device efficiency is observed. This is attributed to efficient blocking of electrons in combination with direct injection of holes from the interlayer to the phosphorescent dye. Upon proper choice of the interlayer polymer, efficient red, polymer-based electrophosphorescent devices with a peak luminance efficiency of 5.5 cd A(-1) (external quantum efficiency = 6 %) and a maximum power-conversion efficiency of 5 Im W-1 can be realized.
Y1  - 2006
U6  - https://doi.org/10.1002/adfm.200500834
SN  - 1616-301X
SN  - 1616-3028
VL  - 16
IS  - 16
SP  - 2156
EP  - 2162
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Yang, Xiao Hui
A1  - Jaiser, Frank
A1  - Neher, Dieter
A1  - Lawson, PaDreyia V.
A1  - Brédas, Jean-Luc
A1  - Zojer, Egbert
A1  - Güntner, Roland
A1  - Scanduicci de Freitas, Patricia
A1  - Forster, Michael
A1  - Scherf, Ullrich
T1  - Suppression of the keto-emission in polyfluorene light-emitting diodes : Experiments and models
N2  - The spectral characteristics of polyfluorene (PF)-based light-emitting diodes (LEDs) containing a defined low concentration of either keto-defects or of the polymer poly(9.9-octylfuorene-co-benzothiadiazole) (F8BT) are preseneted. Both types of blend layers were tested in different device configurations with respect to the relative and absolute intensities of green blue emission components. It is shown that blending hole-transporting molecules into the emission layer at low concentration or incorporation of a suitable hole-transport layer reduces the green emission contribution in the electroluminescence (EL) spectrum of the PF:F8BT blend, which is similar to what is observed for the keto- containing PF layer. We conclude that the keto-defects in PF homopolymer layers mainly constitute weakly emissive electron traps, in agreement with the results of quantum-mechanical calculations
Y1  - 2004
SN  - 1616-301X
ER  -