synthesis of nanophosphors through various chemical routes

Abstract

Material Chemistry is a fast developing subject in material Science and chemistry. Any material can be prepared or synthesized using various chemical routes to obtain the required material for different scientific and engineering applications. newline Phosphor screens are currently in wide use as display devices and they also serve as the interface between information stored in electrons and humans. Universally used phosphor screens in colour televisions are still dominate in the display monitors of desktop computers. newline LEDs for Display applications, the Flat panel technologies like LCD and OLEDs and Active Emitters like LEDs have displaced the CRT from various consumer, industrial, commercial and medical applications. Plasma Displays popular in large TVs are losing ground to LCDs. There are two types of LEDs, one is semiconductor LED and the other one is phosphor converted LED. Semiconductor LEDs are single colour emitters and are used as indicators in so many electronic devices. The emission colour is depends on the energy band gap of the semiconductor material. newline The phosphor converted LEDs (pc-LEDs) are used especially for the generation of white or warm white light for solid state lighting. The generation of white light can be done by two methods. One is by appropriate mixing of the RED, BLUE and GREEN semiconductor LEDs and the other one is by using the phosphors which emits red and green or yellow by absorbing the excitable blue light and the phosphors which emits blue, red and green light by absorbing the excitable NUV light. When a phosphor is exposed to primary radiation (excitation energy), either the host lattice absorbs excitation energy and transfer it to an activator resulting in light emission or the activator absorbs the excitation energy and transfers it to a neighbouring activator (usually identical to the latter) also resulting in light emission. When the activator absorbs the excitation energy, an electron from its ground state is raised to an excited state.