16-05-2012, 11:48 AM
OLED SCREEN TECHNOLOGY
Introduction
We can imagineabout having a TV that is 80 inches wide and less than a quarter-inch thick consumes less power than most TVs on the market today and can be rolled up when we are not using it. What if we could have a "heads up" display in our car or a display monitor built into our clothing or a cellphone which can be folded like cloth? These devices may be possible in the near future with the help of a technology called organic light-emitting diodes (OLEDs).
OLEDs are solid-state devices composed of thin films of organic molecules that create light with the application of electricity. OLEDs can provide brighter, crisper displays on electronic devices and use less power than conventional LEDs or LCDs used today.
OLED Structure and working
OLED is a solid-state semiconductor device that is 100 to 500 nanometers thick.OLEDs generally consist of the following:
• Cathode
• Emissive Layer(organic)
• Conducting layer(organic)
• Anode
• Substrate
Power supply of the device containing the OLED applies a voltage across the OLED. An electrical current flows from the cathode to the anode through the organic layers. The cathode gives electrons to the emissive layer of organic molecules. The anode removes electrons from the conductive layer of organic molecules. At the boundary between the emissive and the conductive layers, when an electron finds an electron hole, the electron fills the hole and gives up energy in the form of a photon of light.
OLED Production
OLED’s are commonly produced using the following methods:
Vacuum thermal evaporation
Organic vapor phase deposition
Inkjet printing
Classification of OLEDS
1. Passive-matrix OLED (uses strips of cathodes and anodes arranged perpendicularly)
2. Active-matrix OLED (uses full layers of cathodes ,anodes and organic layers)
Other Types of OLEDS
a) Transparent OLED
b) Top-emitting OLED
c) Foldable OLED
d) White OLED
Comparison with CRT and LCD screens
CRT (cathode ray tube) monitors cost less and produce a display capable of more colors than OLED displays, But the OLED’s consume very less power and are very light and portable in comparison to the cathode ray tubes
OLEDs have many advantages over the LCDs like lower power consumption and screen refresh rate and better contrast. Also they are more durable and operate in wider range of temperature in comparison to the LCDs. The OLED screens are lighter in weight and highly flexible in comparison to the LCD’s. The major advantage of LCDs is that it is very cheap, but this may change once OLEDs are widely adopted into the consumer market and better production techniques are developed.
Current Applications and Future Scope
Currently, OLEDs are used in small-screen devices such as cell phones, PDAs and digital cameras. Several companies have already built prototype computer monitors and large-screen TVs that use OLED technology.
Research and development in the field of OLEDs is proceeding rapidly and may lead to future applications in heads-up displays, automotive dashboards, billboard-type displays, home and office lighting and flexible displays. Because OLEDs refresh faster than LCDs (almost 1,000 times faster) a device with an OLED display could change information almost in real time. Video images could be much more realistic and constantly updated. The newspaper of the future might be an OLED display that refreshes with breaking news and like a regular newspaper, we could fold it up when we are done reading it and stick it in our backpack or briefcase. The possible applications are immense and with the production cost coming down, OLED technology will definitely be the front runner in the future.
Introduction
We can imagineabout having a TV that is 80 inches wide and less than a quarter-inch thick consumes less power than most TVs on the market today and can be rolled up when we are not using it. What if we could have a "heads up" display in our car or a display monitor built into our clothing or a cellphone which can be folded like cloth? These devices may be possible in the near future with the help of a technology called organic light-emitting diodes (OLEDs).
OLEDs are solid-state devices composed of thin films of organic molecules that create light with the application of electricity. OLEDs can provide brighter, crisper displays on electronic devices and use less power than conventional LEDs or LCDs used today.
OLED Structure and working
OLED is a solid-state semiconductor device that is 100 to 500 nanometers thick.OLEDs generally consist of the following:
• Cathode
• Emissive Layer(organic)
• Conducting layer(organic)
• Anode
• Substrate
Power supply of the device containing the OLED applies a voltage across the OLED. An electrical current flows from the cathode to the anode through the organic layers. The cathode gives electrons to the emissive layer of organic molecules. The anode removes electrons from the conductive layer of organic molecules. At the boundary between the emissive and the conductive layers, when an electron finds an electron hole, the electron fills the hole and gives up energy in the form of a photon of light.
OLED Production
OLED’s are commonly produced using the following methods:
Vacuum thermal evaporation
Organic vapor phase deposition
Inkjet printing
Classification of OLEDS
1. Passive-matrix OLED (uses strips of cathodes and anodes arranged perpendicularly)
2. Active-matrix OLED (uses full layers of cathodes ,anodes and organic layers)
Other Types of OLEDS
a) Transparent OLED
b) Top-emitting OLED
c) Foldable OLED
d) White OLED
Comparison with CRT and LCD screens
CRT (cathode ray tube) monitors cost less and produce a display capable of more colors than OLED displays, But the OLED’s consume very less power and are very light and portable in comparison to the cathode ray tubes
OLEDs have many advantages over the LCDs like lower power consumption and screen refresh rate and better contrast. Also they are more durable and operate in wider range of temperature in comparison to the LCDs. The OLED screens are lighter in weight and highly flexible in comparison to the LCD’s. The major advantage of LCDs is that it is very cheap, but this may change once OLEDs are widely adopted into the consumer market and better production techniques are developed.
Current Applications and Future Scope
Currently, OLEDs are used in small-screen devices such as cell phones, PDAs and digital cameras. Several companies have already built prototype computer monitors and large-screen TVs that use OLED technology.
Research and development in the field of OLEDs is proceeding rapidly and may lead to future applications in heads-up displays, automotive dashboards, billboard-type displays, home and office lighting and flexible displays. Because OLEDs refresh faster than LCDs (almost 1,000 times faster) a device with an OLED display could change information almost in real time. Video images could be much more realistic and constantly updated. The newspaper of the future might be an OLED display that refreshes with breaking news and like a regular newspaper, we could fold it up when we are done reading it and stick it in our backpack or briefcase. The possible applications are immense and with the production cost coming down, OLED technology will definitely be the front runner in the future.