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A G R E AT E R M E A S U R E O F C O N F I D E N C E
Converging Technologies
Speed Up
OLED Development
Steve Greer, Keithley Instruments, Inc.
O
LED technology is already being being investigated for use with OLEDs and of magnitude in time. To characterize the
used in displays for small con- PLEDs. For example, OLED devices based electroluminescence and phosphorescence
sumer products such as PDAs, on small-molecule technology are compat- mechanisms, instruments must provide high
cell phones, and digital cameras, ible with most semiconductor processing sensitivity and precision. Electrical measure-
but there is still a lot of develop- techniques. Now "printable electronics" may ments at femtoamp and microvolt levels are
ment ahead. Organic LED technology has alter the way these FPDs are made. Soft li- common.
not reached the performance and production thography techniques such as microcontact In production, FPD test systems typi-
efficiencies that will make them suitable for printing may make it possible to improve the cally measure junction characteristics of
widespread use in large area displays or with resolution and image definition of OLED the OLED devices and may also perform
high quality video. The convergence of new displays. This or a similar technology could tests on the TFTs. The instrumentation and
materials, production technologies, and re- reduce the cost of producing active matrix test methodology must accommodate the
fined test solutions should accelerate OLED FPDs by depositing thin film transistors relatively high capacitance of these devices
development over the next couple of years. (TFTs) on the same substrate as the OLEDs. without adding excessive test time. Since
In its evolution from LCDs to new organ- These TFTs may also be organic based in- OLEDs are active light-emitting devices, it is
ic and polymer LED technologies, the Flat stead of using the present CMOS technology, important to characterize their light-current-
Panel Display (FPD) industry is grappling which should further simplify production. voltage (LIV) properties under both DC and
with test issues in both R&D and production. New materials, continually shrinking de- pulsed DC operation. With the large number
These issues apply to both small molecule vice structures, and revolutionary processes of pixels arranged in rows and columns, a
OLEDs and polymer (PLED) technologies. are combining to increase the importance of switching matrix is required to speed up FPD
For new designs, material lifetime is a major testing at all stages of OLED development. testing. For best results and lowest cost, each
issue at the R&D stage, and device reliability At the same time, measurements have be- test system is usually tailored to a specific
is always a concern in production. Effective come more demanding. Due to the disordered display technology and physical configura-
testing is required to fully characterize ma- nature of organic material, OLEDs have low tion. By matching test variables as closely as
terials and devices and rapidly move them carrier mobilities. The resulting formation of possible to actual operating conditions, ac-
from R&D into production. space charges produces numerous transient curate modeling and lifetime predictions are
New production technologies are also effects, some of which cover multiple orders possible.
Converging Technologies Speed Up OLED Development April 2004 1
Specifications are subject to change without notice.
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