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DE CORE SCIENCE & TECHNOLOGIES LTD. Access Level: -1

LEDs, its principles and market(Explanation of LEDs, its history, its significance in our daily

lives, its market, its technical principles)

Date : 13-Mar-2013Current Version: V.0 Dated: 13-Mar-2013

Created by:

Shashank Sayanwar

[email protected]

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mailto:[email protected]:[email protected]


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Contents


Contents

1. LEDs

2. History of LEDs

3. Significance of LEDs

4. LED Market

5. LED Principles


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Scope Constraints Exclusions

DE CORE SCIENCE & TECHNOLOGIES LTD.

Scope

This is training cum presentation about fundamentals of LEDs with itsbasic principles, its significance in our daily lives, information aboutits market.

Constraints

This training is restricted to the fundamentals and basic principles ofthe devices and does not contain the advanced principles andexplanation of the working of the device

Exclusions

NA

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Definitions

DE CORE SCIENCE & TECHNOLOGIES LTD

LEDs: LEDs are solid-state semiconductor devices that convert

electrical energy directly into light.

CCT: IESNA Definition: the absolute temperature of a blackbodywhose chromaticity most nearly resembles that of the light source.

CRI: Measure of the degree of color shift objects undergo whenilluminated by the light source as compared with the color of thosesame objects when illuminated by a reference source, ofcomparable color temperature.

Chromaticity: The dominant or complementary wavelength and

purity aspects of the color taken together, or of the aspectsspecified by the chromaticity coordinates of the color takentogether.

Luminous Flux: The rate of flow of light, measured in lumens. The

overall light output of a lamp.

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http://www.lrc.rpi.edu/education/learning/terminology/cct.asphttp://www.lrc.rpi.edu/education/learning/terminology/cct.asphttp://www.lrc.rpi.edu/education/learning/terminology/cct.asphttp://www.lrc.rpi.edu/education/learning/terminology/cct.asp


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Definitions


External Quantum Efficiency (EQE)

The ratio of the number of photons emitted from the LED to thenumber of electrons passing through the device - in other words,how efficiently the device coverts electrons to photons and allowsthem to escape.EQE = [Injection efficiency] x [Internal quantum efficiency] x[Extraction efficiency]

Injection EfficiencyIn order that they can undergo electron-hole recombination toproduce photons, the electrons passing through the device haveto be injected into the active region. Injection efficiency is the

proportion of electrons passing through the device that areinjected into the active region Internal Quantum Efficiency

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Definitions


(IQE - also termed Radiative Efficiency)

Not all electron-hole recombinations are radiative. IQE is theproportion of all electron-hole recombinations in the active regionthat are radiative, producing photons.

Extraction Efficiency (also termed Optical Efficiency)Once the photons are produced within the semiconductordevice, they have to escape from the crystal in order to producea light-emitting effect. Extraction efficiency is the proportion ofphotons generated in the active region that escape from thedevice.**********

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Definitions


Wall-Plug Efficiency (also termed Radiant Efficiency)

Wall-plug efficiency is the ratio of the radiant flux (i.e the totalradiometric optical output power of the device, measured inwatts) and the electrical input power i.e the efficiency ofconverting electrical to optical power.Wall-Plug Efficiency = [EQE] x [Feeding efficiency]

Feeding EfficiencyEach electron-hole pair acquires a certain amount of energy fromthe power source when the LED is operating. Feeding efficiency isthe ratio of the mean energy of the photons emitted and the totalenergy that an electron-hole pair acquires from the power source.

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Raison detre


Learning Outcomes

1. Understanding of fundamentals of LED

2. Understanding of the basic principles of LED

3. Understanding of the parameters of the LED

4. Knowledge of the LED Market

5. Knowledge of LEDs History

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LED (Light emitting diodes)


LEDs are solid-state semiconductor devices that convert

electrical energy directly into light.

LEDs can be extremely small and durable; some LEDs canprovide much longer lamp life than other sources.

The plastic encapsulant and the lead frame occupy most of the

volume. The light-generating chip is quite small (typically a cuboidwith one side equal to 0.25 mm).

Light is generated inside the chip, a solid crystal material, whencurrent flows across the junctions of different materials.

The composition of the materials determines the wavelengthand therefore the color of light.

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In 1960 Dr Nick Holonyak of General Electric was developing an

unusual material, GaAsP, as a route to wide bandgap tunneldiodes.

When an infra-red GaAs semiconductor laser was demonstratedin 1962, Holonyak with his wider bandwidth GaAsP was in theperfect position to have a go at making a visible version.

With advice from GaAs laser pioneer and fellow GE employee DrRobert Hall, Holonyak made his visible laser later in 1962.

It's this October 1962 paper on the GaAsP laser for which

Holonyak became known as the father of the LEDwhere LEDsare defined as visible light emitters based upon minority carrierinjection and radiative recombination of excess carriers.

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The same material is still used to produce deep red LEDs today.

Holonyak had another connection with early light emitters.

He had been John Bardeens first graduate student, the sameBardeen that invented the transistor at Bell Labs in 1947 with WalterBrattain and William Shockley.

Shockley, along with Howard Briggs and James Haynes, appliedfor a patent on infrared LEDs in both silicon (1.1m) andgermanium (800nm) as early as 1951.

The silicon device only appears to have worked at liquid

nitrogen temperatures, but the germanium LED workedcryogenically and at room temperature.

1951 is an early year for LEDs, but it not the first.

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Russian Oleg Vladimirovich Losev reported creation of

the first LED in 1927.

Rubin Braunstein[13] of the Radio Corporation ofAmerica reported on infrared emission from galliumarsenide (GaAs) and other semiconductor alloys in1955.

In 1961 American experimenters Robert Biard andGary Pittman, working at Texas Instruments,[15] found

that GaAs emitted infrared radiation when electriccurrent was applied and received the patent for theinfrared LED.

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http://en.wikipedia.org/wiki/Oleg_Vladimirovich_Losevhttp://en.wikipedia.org/wiki/Light-emitting_diodehttp://en.wikipedia.org/wiki/Radio_Corporation_of_Americahttp://en.wikipedia.org/wiki/Radio_Corporation_of_Americahttp://en.wikipedia.org/wiki/Gallium_arsenidehttp://en.wikipedia.org/wiki/Gallium_arsenidehttp://en.wikipedia.org/wiki/Texas_Instrumentshttp://en.wikipedia.org/wiki/Light-emitting_diodehttp://en.wikipedia.org/wiki/Light-emitting_diodehttp://en.wikipedia.org/wiki/Texas_Instrumentshttp://en.wikipedia.org/wiki/Gallium_arsenidehttp://en.wikipedia.org/wiki/Gallium_arsenidehttp://en.wikipedia.org/wiki/Radio_Corporation_of_Americahttp://en.wikipedia.org/wiki/Radio_Corporation_of_Americahttp://en.wikipedia.org/wiki/Light-emitting_diodehttp://en.wikipedia.org/wiki/Oleg_Vladimirovich_Losevhttp://en.wikipedia.org/wiki/Oleg_Vladimirovich_Losevhttp://en.wikipedia.org/wiki/Oleg_Vladimirovich_Losevhttp://en.wikipedia.org/wiki/Oleg_Vladimirovich_Losev





The first practical visible-spectrum (red) LED was

developed in 1962 by Nick Holonyak, Jr., while workingat General Electric Company.

The first high-brightness blue LED was demonstratedby Shuji Nakamura of Nichia Corporation in 1994 andwas based on InGaN

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http://en.wikipedia.org/wiki/Nick_Holonyakhttp://en.wikipedia.org/wiki/General_Electric_Companyhttp://en.wikipedia.org/wiki/Shuji_Nakamurahttp://en.wikipedia.org/wiki/Nichia_Corporationhttp://en.wikipedia.org/wiki/Indium_gallium_nitridehttp://en.wikipedia.org/wiki/Indium_gallium_nitridehttp://en.wikipedia.org/wiki/Nichia_Corporationhttp://en.wikipedia.org/wiki/Shuji_Nakamurahttp://en.wikipedia.org/wiki/Shuji_Nakamurahttp://en.wikipedia.org/wiki/Shuji_Nakamurahttp://en.wikipedia.org/wiki/General_Electric_Companyhttp://en.wikipedia.org/wiki/Nick_Holonyakhttp://en.wikipedia.org/wiki/Nick_Holonyakhttp://en.wikipedia.org/wiki/Nick_Holonyak




16 Advantages

LEDs produce more light per watt than incandescentbulbs, and are rapidly approaching CFLs.

LED light is directional and can be focused to highlightareas without the use of reflectors.

LED lifetime is not effected by on/off cycling. Fluorescents

burn out more quickly. HIDs require warm up and cooldown periods.

LEDs produce instant light when turned on. They achievefull brightness is micro seconds.

LEDs, being solid state components, are difficult to

damage with external shock, unlike fluorescent andincandescent bulbs which are fragile.




17 Advantages

LEDs are a true GREEN lighting source as they do notcontain any harmful chemicals or gasses. Fluorescentscontain mercury, and Incandescent contains lead.

Average lifetimes frequently average 50,000 hours, andeven up to 100,000 hours in certain applications.

Fluorescents - 15,000 to 20,000 hrs., Incandescent1,500 to2,500 hrs.

LEDs rarely fail to the point of replacement. Fluorescentand Incandescent can burn out completely where LEDfailure is usually classified as light depreciation (fading over

time). LEDs ARE the most efficient light source. In a tough

economy right now, LEDs are a great way to lowermonthly energy bills, and save the planet at the sametime.




18 Advantages

LEDs do not emit any IR or UV. This is especially importantin perishable food displays.



LEDs & Lighting

19 LEDs are used as street lights and in other

architectural lighting. LEDs are used in aviationlighting. Airbus has used LED lighting in theirAirbusA320 Enhanced since 2007. LEDs are also suitableforbacklighting forLCD televisions and lightweightlaptop displays and light source forDLP projectors.

LEDs are also suitable forbacklighting forLCDtelevisions and lightweight laptop displays and lightsource forDLP projectors
http://en.wikipedia.org/wiki/Street_lighthttp://en.wikipedia.org/wiki/Airbushttp://en.wikipedia.org/wiki/Airbus_A320_Enhancedhttp://en.wikipedia.org/wiki/Airbus_A320_Enhancedhttp://en.wikipedia.org/wiki/Backlighthttp://en.wikipedia.org/wiki/Liquid_crystal_displayhttp://en.wikipedia.org/wiki/Laptophttp://en.wikipedia.org/wiki/Digital_Light_Processinghttp://en.wikipedia.org/wiki/Backlighthttp://en.wikipedia.org/wiki/Liquid_crystal_displayhttp://en.wikipedia.org/wiki/Laptophttp://en.wikipedia.org/wiki/Digital_Light_Processinghttp://en.wikipedia.org/wiki/Digital_Light_Processinghttp://en.wikipedia.org/wiki/Laptophttp://en.wikipedia.org/wiki/Liquid_crystal_displayhttp://en.wikipedia.org/wiki/Backlighthttp://en.wikipedia.org/wiki/Digital_Light_Processinghttp://en.wikipedia.org/wiki/Laptophttp://en.wikipedia.org/wiki/Liquid_crystal_displayhttp://en.wikipedia.org/wiki/Backlighthttp://en.wikipedia.org/wiki/Airbus_A320_Enhancedhttp://en.wikipedia.org/wiki/Airbus_A320_Enhancedhttp://en.wikipedia.org/wiki/Airbushttp://en.wikipedia.org/wiki/Street_light



LEDs & Lighting

20 The lack of IR or heat radiation makes LEDs ideal for

stage lights using banks of RGB LEDs that can easilychange color and decrease heating fromtraditional stage lighting.

LEDs are used for infrared illumination in night visionuses including security cameras.

LEDs are increasingly finding uses in medical and

educational applications.

l d l ( )
http://en.wikipedia.org/wiki/Stage_lighthttp://en.wikipedia.org/wiki/Night_visionhttp://en.wikipedia.org/wiki/Security_camerahttp://en.wikipedia.org/wiki/Security_camerahttp://en.wikipedia.org/wiki/Night_visionhttp://en.wikipedia.org/wiki/Stage_light


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21

Correlated Color Temperature (CCT)

Measures the "warmth" or "coolness" of a light

sources appearance in degrees Kelvin (K) againstreference light sources

Incandescent color temperatures are about 2,700oK

Daylight lamp color temperatures are 5,000o K +

Indirectly relates to energy savings

Higher color temperature lamps appear brighter

A subjective index depending on personalpreference

C l d C l (CC )


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Correlated Color Temperature (CCT)

C l R d i I d (CRI)


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Color Rendering Index (CRI)

A measure of a light source's ability to render the

color of objects "correctly," as compared to areference light source of comparable colortemperature

The scale is between 0 and 100

Generally, the higher the number, the better

Color swatches used to determine CRI are red, green,and blue

A subjective index: depends on personal preference

C l R d i I d (CRI)


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Color Rendering Index (CRI)


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Other Important Lighting Definitions

Lampgeneric term for a light source

Ballastelectronic device that drives thelamp(s)

Lumentotal amount of light produced

Foot-candleone lumen/square foot Light Levelsynonymous with foot-candle

Efficacy (lighting efficiency) - lumens/watt

HOhigh output fluorescent lamp

VHOvery high output fluorescent lamp

HPHigh Performance T8 lighting system


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The luminous efficacy of a light source is the

ratio between the emitted luminous flux andthe amount of the absorbed energy totransmit it. It is expressed in lumen/watt (lm/W).

The lumen, the measure unit of the luminous

flux, is equal to the luminous flux detected in asolid angle of one steradian and emittedtowards all directions from a source with aluminous intensity of 1 candle.


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The steradiansr symbol- is the SI unit of solid

angle and it is defined as " the solid anglesubtended at the center of a sphere of radius rby a portion of the surface of the spherehaving an area r ". Since the area of the

sphere is 4r, as a consequence the solidangle subtended by the whole sphere is equalto 4sr).


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Moreover, the luminous flux is defined on the

basis of the subjective perception of themedium human eye and it corresponds to aparticular curve inside the spectrum of thevisible light.

A light bulb emits radiation even outside thevisible spectrum, (usually in the infrared and inthe ultraviolet wavelength), which does notcontribute to the brightness perception. Alamp has a higher luminous efficacy as muchas it is able to emit a spectrum suitable for thehuman vision

h h f


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k


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LEDs Market

30 The market is on clear transition path from

traditional lighting technologies to LED

Regulation across the globe has become morestringent, fueling the penetration of more energy

efficient light sources

LED prices have eroded more aggressively, pullingforward the payback time of LED lighting

The total market is expected to grow annually by 5percent through by 2016, and by 3 percentthereafter until 2020.

LED M k


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LEDs Market

31 Asia is expected to account for approximately 45

percent of the global general lighting market by2020.

Value in the LED chip and package market is set to

shift from backlighting to general lighting.

The lighting control system market is alreadymushrooming, with a growth rate anticipated at

almost 20 percent per annum.

LED M k


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LEDs Market

32China has passed a legislation to ban

incandescent lightbulbs.Govt has also reacted to the disaster in fukushima

by debating the nuclear phaseout. This is expectedto boost the uptake of low-energy light sourcesthat help to close the looming energy gap.

The LED prices have eroded more aggressively,pulling forward the payback time of LED lighting.The LED share in general lighting will be 45 percentin 2016 and almost 70 percent in 2020.

Asia currently leads the the market transition to LEDin general lighting, driven especially by swiftpenetration in China and Japan.

LED M k t


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LEDs Market

33 Factor fueling the further uptake of LED

LED is regarded as the most promising technology in termsof commercial viability in 2020 from among several kindsof clean technologysuch as photovoltaic solar power,wind power, and electric vehicles.

The price of LEDs is tumbling even faster than anticipated,

helping to further drive technology transition. One is theconsiderable overcapacity of LED Chips and packageshas built up due to huge investments in LED Chip/packageproduction lines in China.

Alongside the price reduction trends triggered in thebacklighting segment, the low price LED Chips andpackages has begun flowing into the general lightingsegment, especially low to mid power range LEDcomponents, which are mainly for diffuse area lighting.

LED M k t


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LEDs Market

34 Factor fueling the further uptake of LED

The LED has expanded the application space for thesegment by new products, such as media facades andnew kinds of entertainment lighting. In addition, LEDs haveadvantages, such as RGB color controllability, andflexibility.

LED M k t


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LEDs Market

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CONCLUSIONS

THANKS

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