Light Emitting Polymers 1 1

INTRODUCTION Polymer which emits light (EM radiations). Polymers are chains of smaller molecular components called Monomers. CDT & UDC are developing LEP display. (Cambridge Display Technology & Universal Display)

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.

ARCHITECTURE 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

HOW TO WORKS? 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.

MANUFACTURING SPIN COATING PROCESS A spin-coating machine is used that has a plate spinning at the speed of a few thousand rotations per minute.

MANUFACTURING… PRINTER BASED TECHNIQUE LEPs can be patterned using a wide variety of printing techniques. The most advanced is ink-jet printing. Resolution as high as 360 dpi have been demonstrated and the approach are scalable to large-screen displays. Printing promises much lower manufacturing cost.

TYPES OF LEPS Flexible Stacked organic (SOLEP) Transparent organic (TOLEP)

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

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.

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.

CONCLUSION It has both electrical and optical property. It is simpler & cheaper. It permits flexible lighting and display. It is technology for the future.

PPT Source: www.studymafia.org Thanks PPT Source: www.studymafia.org