A modelling approach for carrier transport in a Gaussin density of states is presented which takes into account that the
energetic distribution of carriers moving via Miller-Abrahams rates is affected by an electric field. This reorganisation of
the energetic carrier distribution can be described by virtual carrier heating to an effective temperature. We show that
combining this approach with an existing percolation model reproduces the field dependence found in computer studies
in literature for uncorrelated Gaussian disorder. Comparing to our experimental results, we also demonstrate that the
parameterizations from these publications do not hold at low temperatures.
We produced samples of 4,4′,4″-tris-(2-methylphenyl phenylamino)triphenylamine (m-MTDATA) doped into N,N'-
diphenyl-N,N'-bis(1-naphthylphenyl)-1,1'-biphenyl-4,4'-diamine (NPB) in the ratio 1:1 with four different thicknesses
from 50 nm to 400 nm and measured the IV curves in a temperature range from T=77 K to 346 K. We successfully
demonstrate a unified simulation of the samples’ IV characteristics over the entire temperature range under the
assumption of carrier heating, which is not possible with published models for correlated and uncorrelated Gaussian
disorder.
Efficient white OLEDs are becoming attractive as large area light sources for illumination and in future also for general
lighting. We discuss device concepts for white OLEDs and their potential to achieve high efficacy and good lumen- and
color-maintenance at the same time. We focus on OLEDs using a combination of fluorescent blue and phosphorescent
red and green emitters (hybrid OLEDs). Hybrid OLEDs have high efficacy and lifetime in the white to warm white color
region (color points B and A on the black-body-curve). Near illuminant A efficacy values of 28-29 lm/W without optical
out-coupling can be achieved with a hybrid OLED. The external quantum efficiency (EQE) is 14%. A typical color
rendering index (CRI) is 84. Recent results for monochrome OLEDs and for hybrid OLED stacks are presented.
Organic light emitting diodes (OLEDs) provide potential for power-efficient large area light sources that combine
revolutionary properties. They are thin and flat and in addition they can be transparent, colour-tuneable, or flexible. We
review the state of the art in white OLEDs and present performance data for three-colour hybrid white OLEDs on indexmatched
substrates. With improved optical outcoupling 45 lm/W are achieved. Using a half-sphere to collect all the light
that is in the substrate results in 80 lm/W. Optical modelling supports the experimental work. For decorative applications
features like transparency and colour tuning are very appealing. We show results on transparent white OLEDs and two
ways to come to a colour-variable OLED. These are lateral separation of different colours in a striped design and direct
vertical stacking of the different emitting layers. For a striped colour tuneable OLED 36 lm/W are achieved in white with
improved optical outcoupling.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.