Diode : LED, OLED, FLED, PLED Devices

[ODCAD] Sharp-Blue Laser Diodes

2004-06-25T13:26:00.000-07:00

Blue-violet Laser Diode is one of the components used in next generation of DVD. This high density (27 gigabits/disc) DVD requires Blue laser light to record digital information. The lab of Sharp in UK has developed a method to make this diode. The material is Indium-Gallium-Nitride (InGaN). This lab used a technique of molecular beam epitaxy (MBE). Sharp has already used this technique to manufacture Red laser diodes. This new method can compete with the others[1] that have been protected by patents.

1. Blue-laser using metal organic chemical vapor deposition developed by Shuji Nakamura, Nichia Corp, Tokushima, Japan

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[ODCAD] Sharp-Blue Laser Diodes

2004-06-07T16:47:00.000-07:00

[ODCAD] Philips-high efficiency polymer OLED (breakthroughs)

2004-05-12T16:37:00.000-07:00

Improvement of power efficiency is critical for success of OLED display technology. Scientists from Philips claims that a breakthrough in that aspect has been made.

One development Philips made is using proper hole transportation layer (HTL) material. Usually, conductive polymer has more hole injected than electron, which results in waste of energy from extra hole. Choosing proper HTL material to reduce the hole injected can improve the power efficiency. (Sounds like anode junction barrier is increased) The quantum efficiency has been raised to 12% that is about 3 to 6 times higher than standard OLED devices.

Another development Philips made is dispersing a phosphorescent guest material into a light emitting polymer host. The polymer host used by Philips is carbazole-oxadiazole derivative. The guest material is iridium complex. A research fellow Meulenkamp from Philips presented the work on April 28, 2004 at the International Society for Optical Engineering's Photonics Europe conference in Strasbourg, France. Philips expects that these developments can significantly improve polymer OLED (PLED) device performance.

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2004-05-04T09:36:00.000-07:00

[ODCAD] Slow Mobility :Organic Semiconductor as Device Material

Organic semiconductor,usually, has very low conductivity. Eeven in
crystal phase of the organic semiconductor, its conduction is still
poor. Conductivity is
contributed by two factors (mobility x concentration).

Let us consider simple case in which there is one charge carrier (say
hole) in the material. The "Concentration" is the
concetration of charge carrier whose intrinsic value is usually low
in organic semconductor. This factor is not discussed here. The 2nd
factor is the mobity of the charge carrier.

The charge carrier mobility in organic material is usually less than
1 cm2/V-s. The best so far is about 5 cm2/V-s for crystal organic
semiconductor. For polymer, the mobility is usually <0.0001 cm2/V-s.
There are many reasons to cause this for organic material and they
are not discussed here.

Is low conductivity good or bad for the application of device?
The answer is "depends". If the application is involved high current
going through the material. That is bad because the device requires
high voltage to operate resulting large heat generation. Both high
energy and large heat should be avoided in device design.

However, if the application just requires sensitivity of the device
to the change of operation condition (say change of voltage), for
example, field effect transistor. The operation then just involves
small current because of the low conductivity. This is particular
true when the device has very thin film (um or nm range) of the
material.

Well, one short coming of slow mobility is the speed. If the
device requires quick response, slow mobility will be issue. Some
device may need speed that can be reached by organic material. For
example, display device for TV, PDA, computer monitor etc, do not
mind the response time in micron sec or even longer time. This is
particularly true for large area electronic product. A few
applications such as logic transistor used for CPU require very fast
response of the device. Slow mobility will be big issue. That is why
the industry put a lot of effort to improve the mobility of organic
material. Mobility of charge carrier of material used in transistor
is a significant indicator of the material.

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2004-05-03T09:14:00.000-07:00

[ODCAD] Coming Events in May, 2004

May 4, Singapor: Semicon 2004
Location: Singapore International Convention and Exhibition Centre (SICEC)
When :May 4-6, 2004
More Info:http://www.semi.org/wps/portal/_pagr/103/_pa.103/259?
id=19040&startRow=1

May 4 US: The 15th Annual IEEE/SEMI Advanced Semiconductor
Manufacturing Conference
Location: Seaport Hotel,Boston, Massachusetts, USA
Mre Infor: http://www.semi.org/wps/portal/_pagr/103/_pa.103/259?
id=18967&startRow=1

Ma 7 Bay Area, CA, US:IEEE EDS/SCV Evening Seminar in Bay area, CA
Location: National Semiconductor, Building 31, 955 Kifer Rd.
Sunnyvale, CA
Topic: Compact Modeling
When: 6-8 PM
Admission: Free

May 17 NY, US: Nanobusiness Conference
Location: Marriott Financial Center, NY
More Info :snemeth@penton.com

May 23-28 Seattle, US: SID Display 2004
Location: Washtington Sate Convetion and Trade Center
More info :http://www.sid.org/conf/sid2004/sid2004.html

May 25 Pennsylvania, US:Pennsylvania Nanotechnology Conference 2004
Location: The Pennsylvania Convention Center, Philadelphia, PA
More Info: http://www.pananoconference.org/

To check events in June or later, visit
http://groups.yahoo.com/group/OrganicDevice/, chect its calendar, and
add interesting event to yours.

ODCAD from OD Software Incorporated (ODSI) (http://www.odcad.com/)-the expert, and toolkit provider of electronic material, device.

2004-05-01T12:59:00.000-07:00

[ODCAD] GE: OLED as Lighting

GE recently said that it made a breakthrough with a 24x24 inch2 white organic light emitting diode lighting prototype. Its efficiency is 15 lumens/W. This project is sponsored by Dept of Energy. The major challenge is to reduce the manufacture cost with much higher energy efficiency (target is 100 lumens/W).

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