Osram has recorded yet another important success with regard to
research in the field of organic light diodes (OLED). The
company’s researchers have developed so-called
“flexible” OLED, which attain an efficiency of 32 lm/W
– which is a record value. In so doing, after the rigid OLED,
OSRAM has now also reached an important milestone on the road to broad
commercial application for flexible OLED.
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In lab tests OSRAM was successful at achieving lighting values of 32lm/W for the flexible OLED – a new peak value.
Source: OSRAM |
A central challenge in the field of OLED development is to succeed at
achieving an efficiency increase, whilst at the same time attaining
consistently good performance characteristics. It is the prerequisite
to ensure that OLED can prevail as a widespread form of lighting
technology, complementary to LED. OSRAM has now succeeded in attaining
a record efficiency of 32 lm/W for flexible OLED. The technical basis
for this success is provided by a special electrode design. The
substrate for the OLED is a steel foil with a thickness of
approximately 100 micrometers – thus meaning it is as thin as a
sheet of paper. Because this steel foil is opaque, the light cannot
shine through it as would be the case with rigid OLED on glass, but has
to shine to the upper side. This so-called “Top-Emitter”
technology makes it more complicated to design high-quality white
light.
For the OSRAM researchers it was important to ensure that both the OLED
as well as the test would be created as realistically as possible, so
as to ensure that it would provide the opportunity to draw conclusions
for the subsequent commercial application. For this reason a
large-surface OLED sample was tested, and not a smaller reference part.
The brightness setting was fixed at 1,000 cd/m². The measurements
were made in an integrating sphere – without using any
manipulating macroextractors such as, for instance, lens assemblies,
which have the purpose of increasing the light yield.
Towards mass applicationResearch samples such as the record OLED represent an important step on
the road to providing flexible OLED in widespread commercial
application. “With this research success, OSRAM further
underscores its leading position in the field of OLED,” said
Ulrich Eisele, head of OLED at OSRAM. The head of technology, Thomas
Dobbertin, supplemented this comment by stating that “with this
sample, we are able to demonstrate that flexible OLED can already be
significantly more efficient than halogen lamps. This was only made
possible thanks to our ability to transfer our strong competence in the
field of vacuum processing of organic functional materials and space
saving thin film encapsulation onto flexible OLED.”
In the recent past, Osram continued successfully to set standards in
the field of OLED technology: in this regard, a value of 87 lm/W was
recently attained with the conventional glass version. This value is
almost equivalent to the efficiency of a fluorescent lamp. The first
pilot production line for OLED was opened in Regensburg at the end of
August. At the same time, the technology is also being deployed in a
permanently increasing number of applications. The first solutions in
the field of office applications and retail have already been put into
operation in Munich and Berlin.
When viewed from a purely technical aspect, OLED refers to
semiconductors that convert electricity into light, as is the case with
the sister technology LED. Whilst LED emits punctiform light that is
derived from an extremely small luminous chip, the so-called OLED
panels generate an illuminating surface. For this, a variety of
different organic synthetic materials are evaporated onto a basic
material. The illuminating OLED layer has a thickness of approx. 400
nanometres – which is equivalent to one hundredth the thickness
of a human hair. Depending on the basic material that is utilised, when
OLED are switched on, they can be designed either in a mirroring,
neutral white or transparent light.
The record results were attained within the context of the grant
project TOPAS2012. The joint project of the Federal Ministry of
Education and Research (grant project number 13N10474) supports the
OLED research being done at OSRAM. The objective of the project is to
further develop OLED as lighting of the future.
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