World’s Thinnest Light Bulb: Importance of Innovative Invention

World’s Thinnest Light Bulb: Importance of Innovative Invention

Question: Graphene, a carbon form is stronger than steel and more conductive than copper. It is also used for making the world’s thinnest light bulb. Highlight how this light bulb works and the importance of this unique invention.

• Researchers have developed a light emitting graphene transistor working in the same way as a filament in a light bulb

• Columbia University researchers in NY led by co author James Hone have created the world’s thinnest light bulb using graphene

• This has been possible through enabling of photonics circuits running on light rather than electric current

• New graphene device is efficient and tiny and it could offer novel ways to create displays or study high temperature phenomena

How It Works

• When the electric current is passed through the filament, it heats up and flows

• Scientists used graphene strips a few microns across from 6.5 to 14 microns in length, spanning a trench of silicon akin to a bridge

• Micron is one millionth of a metre where hair strand is around 90 microns

• An electrode was attached to each end of the graphene strip and running a current through the graphene causes the material to light up

• As graphene conducts heat less efficiently with increase in temperature, heat stays at a spot in the centre rather than even distribution characteristic of a tungsten filament

• Trapping heat in one of the regions makes lighting more efficient

• This is also why electrodes placed at the end of graphene do not melt

• Graphene is usually embedded or in contact with a substrate

• Light emitted from the graphene also reflected from the silicon that each piece was suspended in front of

• Reflected light interferes with emitted light influencing pattern of emission with peaks at different wave lengths

• Thus light can be tuned through variance in the distance to the silicon

• This is the principle on which the graphene filament works

Facts and Stats

• The temperature of hot electrons at the centre of the graphene is about 3,000 K or 4,940 F, while the graphene lattice temperature is still about 2,000 K or 3,140 F

• Scientists from Columbia, Seoul National University, and Korea Research Institute of Standards and Science have demonstrated an on chip visible light source using graphene as a filament

• Small strips of graphene pass currents through filament causing the bulb to light up
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