QUANTUM DOTS SREELAKSHMI S S 3 EC ROLL

QUANTUM DOTS SREELAKSHMI S S 3 EC ROLL NO: 55

INTRODUCTION Quantum Dot (QD) is a nano crystal made of semiconductor materials that are small enough to exhibit quantum mechanical properties. Researchers have studied applications for QD in Transistors, Solar Cells, LEDs, and diode lasers. 2

WHAT ARE QUANTUM DOTS. . . ? Ø QD was invented in 1983 by Brus as some small semiconductor spherical particle in colloidal suspension. Ø QDs are semiconductor nanocrystals. Ø They are made of the same ordinary semiconductor materials(combination of transition metals or metalloids). Ø Unlike ordinary semiconductors, QDs are extremely small (usually 2 -10 nms). 3

COLOUR EMISSION BY QD 4

SYNTHESIS OF QD Ø CHEMICAL SYNTHESIS The most accessible technique is colloidal synthesis - that is, chemically producing quantum dots suspended in solution. One method for producing Cd. Se is shown in Fig, but a variety of chemical synthesis routes are possible for each semiconductor material. 5

APPLICATIONS OF QD ü Medical Imaging and Diagnosis • QDs can be useful for monitoring cancerous cells and providing a means to better understand its evolution. • It can be used in tumour fighting toxic therapies. • QDs are much more resistant to degradation than other optical imaging probes. 6

üQuantum Dot LEDs • Gives high peak brightness in LED TV. • Gives better colour accuracy and colour saturation. 7

üSolar cell and photovoltaic cell 8

ADVANTAGES OF QD • They are water soluble substance. • QDs as p. H probes was found to be more convenient, rapid and specific method for kinetic studies. 9

DISADVANTAGES OF QD • QD maybe toxic according to its composition which includes some heavy metals , and also the degradation of QDs is still unknown specifically inside the living organism 10

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