light emitting polymers


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light emitting polymers

  1. 1. WELCOME•
  2. 2. By VISHNU MOHAN V.MSeminar guides,Athira A.PDivya nateshan
  4. 4. INTRODUCTION LEP or PLED or P OLED Polymer which emits light(EM radiations). Polymers are chains of smaller molecular components called MONOMERS. CDT & UDC are developing LEP display.
  5. 5. HISTORY 1977 conducting polymers are discovered. Alan J. Heeger , Alan G. MacDiarmid got Nobel prize From this OLED evolved. In 1990 Friend et al found Electroluminescence in the conducting polymers. Birth of “LIGHT EMITTING POLYMERS”!!!!!!!!!!! Poly phinylene vinylene (PPV) is the first LEP discovered.
  6. 6. About LEP………..Electroluminescence is the principle behindthe LEP.LEP comes under the category ofconjugated polymers.Polymers with metallic andsemiconductor characteristics.Delocalized pi electronsBand gap ranges from 2.2 to 2.8 evWave length depends on the band gap ofLEP.
  7. 7.  Thin film of semiconducting polymer sandwiched between an ANODE and CATHODE. Metal Cathode Polymer ANODE: ITO(Indium Tin Oxide) CATHODE: Metals (depends upon the type of LEP) Glass Substrate SUBSTRATE: Glass, clear plastic (depends upon the type of LEP) Transparent Anode (ITO) Voltage is applied between anode and cathode
  8. 8.  Due to applied voltage electrons and holes will migrate to polymer lattice. They will combine together to form excitons Excitons returns to initial state by emitting radiation.
  9. 9. MATRIX DISPLAYS PLED displays consists of matrix of pixels. Each pixel is a light emitting polymer. Emit light by turning OFF and ON the pixels. Primary color pixels are positioned very close to form other colored pixels To control each pixel DRIVERS are needed. DRIVERS are Transistors • 2 matrix
  11. 11. PASSIVE MATRIX DISPLAY Each row and column have its own drivers. The organic layer is between strips of cathode and anode. Intersection forms the Pixel. Matrix scan every pixel to switched on or off as required. Data signal is send to the pixel sequentially. If brightness is to increase, current through that electrode will be increased.
  12. 12. Passive matrix displays…… Easy to make. Use more power. If size of display will become difficult. Each pixel only emits light for a small length of time. Flickering is more. Only for small displays.
  13. 13. ACTIVE MATRIX DISPLAYS Each pixel is addressed by incorporating a TFT. Brightness of each pixel is controlled by TFT. TFT will hold the current. Current flow is controlled by setting TFT drivers. More efficient than passive matrix displays. Can be used in large area displays. AMOLEP or AMOLED
  14. 14. HOW IT IS MADE………………………………….?
  15. 15. • Substrate is placed on spinningSTEP 1 plate. • Plate is spinning at a speed of few thousand rotation perSTEP 2 minute. • Robotic arm will pour small amount of polymer solution toSTEP 3 the substrate. • After spreading ,it is baked toSTEP 4 evaporate any remaining liquid. • Extremely fine layer of polymers having a thickness of aboutSTEP 5 100nm
  16. 16.  Ink-jet head, Ink and substrate for printing are different Primary colour polymers are jetted to the substrate. Uniformly spread the substrate. Mainly used for printing LEP images. Also used for making large display.
  17. 17. TYPES OF LEP……….(PLED) Flexible Organic Light Emitting Polymers(FOLEP). Stacked Organic Light Emitting Polymers(SOLEP) Transparent Organic Light Emitting Polymers(TOLEP)
  18. 18. FLEXIBLE ORGANIC LEP(FOLEP) Built on a flexible substrate. They have the ability to conform, bend or roll a display into any shape. They are less fragile and more impact resistant. Ultra lightweight & thin form.
  19. 19. TRANSPARENT ORGANIC LEP(TOLEP) Substrate is transparent. LEPs sandwiched between 2 transparent layers. Top and bottom emitting layers. High resolution. More than 70% transparent when turned off. Better efficiency. Faster response.
  20. 20. STACKED ORGANIC LEP(SOLEP) Array of vertically stacked TOLEP sub-pixels. Color is tuned by individually controlling R-G-B sub pixels Brightness is adjusted by adjusting the total current in the stack. It will only turn on the desired color pixel only. Can be used in large displays True color quality.
  21. 21.  Screen Refreshing Rates  Higher than LCD Viewing quality  Higher than LCD Screen size  Size is not limited in LEP display Viewing angle  Glare free up to 170 degree Power consumption  Lesser than LCD
  22. 22. ADVANTAGES….. Require only 3.3v & life time of more than 30,000 hr. Low power consumption. Self luminous. No viewing angle dependence. Manufacturing cost is less. Can be scaled to any dimension. No environmental draw backs. Simple to use. Very slim flat panel displays.
  23. 23. DISADVANTAGES…… Voltage drops may affect the performance. Limited market availability. Aging of LEP  Degradation of luminescence  Light intensity gradually decreases.  Disintegrate due to contact with oxygen.
  24. 24. APPLICATIONS…… Multi or full color cell phone displays Full color high-resolution personal digital assistants(PDAs) Lightweight wrist watches Roll-up daily refreshable electronic newspapers Automobile light systems without bulbs
  25. 25. FUTURE SCOPES…. LEP-in future cars
  26. 26. LAPTOPS……
  27. 27. TELEVISIONS…
  28. 28.  Have both electrical and optical property A low cost solution for flat panel display. Many manufactures are working to introduce a revolutionary changes in the market. Hazardless to environment. Simpler and cheaper Have some limitations Till it is the superior technology………for the future…..
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