Tuesday 31 January 2017

OLED - Part 1

     Present day smart phone display screens are almost made up of OLED (Organic Light Emitting Diode).  Television screens that uses OLED are also available. Due to their high cost it is not ubiquitous in the TV market. OLED emerges as the promising display technology of near future.

Introduction to LED
    Diode is an electronic device. Electronics is a branch of science that deals with study of flow of electrons in a semiconductor or vacuum or gas. Semi is a Latin prefix meaning 'half'. Group 4 elements like Silicon and Germanium has four electrons in the outer orbit and they behave as a perfect semiconductor. Diode is a two terminal device. When current passes through typical diode, small amount heat or infra red emissions occur. But in the case of Light Emitting Diode (LED) instead of heat, light is produced. At present organic materials like polymers are used to make LED. 

Figure 1. (a) Typical LED (inorganic) (b) Symbol for diode (c) Symbol for LED   Image Courtesy: Wikipedia
Organic Polymers
    General public associate the word “Organic” with a produce that is free  from artificial chemicals. In science the word organic is associated with carbon compounds like carbonates, oxides, hydrocarbons and so on.
    Polymers are made up of long chains of molecules. Almost all polymers are organic in nature. Few Inorganic polymers also do exist. Silicone is a best example for inorganic polymer.