**1. A succinct evidence of light-emitting diode**

Amid the supreme contemporary machineries in lamps and lighting devices, Light-emitting diodes (LEDs) have an enormous amount of novel applications day by day, and flattering ever more prevalent and manageable to the societal benign. Basically, the LED is connected to direct current which emits light in the visible region of spectrum. While experimenting with silicon carbide (crystal detectors) and a cat's whisker, the first discovery of electroluminescence phenomenon using light emitting diode was noticed back at the beginning of the twentieth century (1907), by a British radio engineer H J Round and the assistant to Guglielmo Marconi [1, 2]. In 1927, the phenomenon of electroluminescence in the diodes used in radio sets was studied by a Russian radio researcher Oleg Vladimirovich Losev. Also a credit toward his research, he has published a paper named Luminous carborundum [silicon carbide] detector and detection with crystals [3]. At room (298 K), low (77 K) temperature and even in other semiconductor alloys, the infrared emission was observed by employing the simple diode structures with indium phosphide (InP), silicon-germanium (SiGe), gallium arsenide (GaAs), and gallium antimonide (GaSb) alloys by Rubin Braunstein in 1955 [4]. Years later in the fall 1961, the first infrared LED was invented and patented by Robert Biard and Gary Pittman [5–7]. In 1962, the first visible red LED was invented by Nick Holonyack, using gallium arsenide phosphide (GaAsP) as a substrate for the diode [8]. By employing gallium arsenide phosphide in the diode, the first yellow LED was invented by M George Craford in 1972 [9]. In 1968, the Monsanto Company was the leading group of institution has made a mass-production of visible red LEDs as indicators using gallium arsenide phosphide (GaAsP). Nevertheless, it was not in anticipation of the 1970s that LEDs befitted popular as

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

soon as Fairchild Optoelectronics instigated manufacturing the low-cost LED devices [10]. In 1976, Thomas P. Pearsall invented a new semiconductor LED materials to be used in fiber optics and telecommunication systems with tremendously bright and high efficiency [11]. In 1979, first blue LED using gallium nitride (GaN) was designed by Shuji Nakamura of Nichia Corporation. By dint of creative techniques, the Fairchild Optoelectronics have made LED into profitable manufactured goods with diversity of usages based on packaging and a planar process of chip production. [5–8].

**Light-emitting diode (inorganic LED) Organic light-emitting diode (OLED)**

1907 The first discovery of

electroluminescence

and a cat's whisker

1935 The French physicist Georges Destriau discovers light emission (electroluminescence) in zinc sulfide. Further the effect can be called as "Lossew Light".

1939 Zoltan Bay together with

diodes (LEDs).

1951 After the discovery of transistor, Shockley and his collaborators Howard Briggs and James Haynes applied for manifest on infrared LED by employing Germanium and Silicon.

Gyorgy Szigeti received a U.S. patent on "Electroluminescent light sources" which were made of a lighting device using SiC, with an possibility on boron carbide (BC), that emitted white, yellowish white, or greenish white contingent on impurities present; these light sources were the ancestors of light-emitting

*Oleg Vladimirovich Losev* was experimenting the phenomena of electroluminescence (dealing with the emission spectrum of light radiation in regard to the current–voltage physiognomies of SiC cat's whisker diodes) in the diodes especially employed in radio sets. He has inquisitively published an article called Luminous carborundum [silicon carbide] detector and detection with zincite & iron glance crystals.

1927 A Russian radio researcher

phenomenon using light emitting diode were noticed back at the beginning of the twentieth century, was discovered by a British radio engineer *H J Round* and assistant to *Guglielmo Marconi* while investigating with silicon carbide (crystal detectors)

Year Historical development Ref. Year Historical development Ref.

André Bernanose and coconspirators at Université de Nancy, France, consummate the first innovations of electroluminescence in organic materials. By applying the high alternating voltages in air to materials for instance acridine orange (*N,N,N′,N′*- Tetramethylacridine-3,6-diamine), whichever set down on or melted on the thin film layer of cellophane or cellulose. The mechanism put forward of any kind of excited electrons or direct excitation of the dye molecules.

http://dx.doi.org/10.5772/intechopen.79375

[3, 4] 1960 From New York University, Martin Pope and

OLED gadgets.

Introductory Chapter: The Impression of Light-Emitting Diodes in Space-Age Advancements…

[5–8] 1963 Pope's group as well first perceived

fluorescence.

level of exciton.

[5–8] 1965 For the first time, W. Helfrich and W. G.

[5–8] 1965 Pope's group described the nonoccurring of

few of his accomplices fabricated the ohmic dark-injecting electrode contacts to organic crystals. These acquaintances are the root of injection of charges in all contemporary

direct current (DC) electroluminescence under vacuum on a single pure crystal of anthracene and on anthracene crystals doped with tetracene based on a lesser area silver electrode at 400 V under the process of fieldaccelerated electron excitation of molecular

an external electric field, the recombination of a thermalized electron and hole electroluminescence mechanism can be instigated on anthracene crystals, and as a result the conducting level of anthracene dwell in the higher energy than the energy

Schneider developed the double-injection recombination electroluminescence in an anthracene single crystal by the usage of hole

and electrons injection electrodes.

[30–33]

3

[34, 35]

[36]

[37]

[38]

[1, 2] 1950 to 1955

Among the utmost topical technological advancements in lamps lighting devices, LEDs have enormous amount of application niches. Day by day, LEDs are flattering more attractive and more accessible to the common people. For the past few decades semiconductor technology has progressed to greater statures. The result is in the form of smart gadgets and the LEDs which give enhanced illumination with low power ingesting and better life span too.

The LED can be lingering further into three major categories are: (1) traditional inorganic LEDs, (2) organic LEDs (small molecule OLED, polymer LED, passive matrix OLED, active matrix OLED), (3) high brightness LEDs. Further, **Table 1** provides the detailed information about the historical developments in LED and OLED [1–55].

**Traditional Inorganic LEDs:** By employing various inorganic materials, the traditional type LEDs are made and therefore called as inorganic LEDs. A number of extensively used LEDs have been fabricated using semiconductor materials like aluminum-gallium arsenide (AlGaAs) and indium-gallium nitride (InGaN). Furthermore, with different doping concentrations in inorganic semiconductor material, the traditional inorganic LEDs are used nowadays. These are obtainable in souk with various sizes, shapes and colors like single color LED, surface mounted LED, flashing LED and multicolor LED.

**Organic LEDs:** Using organic materials, the organic LEDs have been fabricated, which are fictitious from carbon-based polymers and semiconductors. Organic light-emitting diode (OLED) is a thin film of organic compound which consists of a PN junction made by an emissive electroluminescent layer. Further, the emissive layer emits light in Ref. to an electric current and this layer of organic material is positioned among two electrodes. In general, it is realized that as a minimum one of the electrodes must be a transparent one. The organic LEDs are factory-made in the form of thin films; hence, these are given that a small portion for diffusion through which the light engenders, and these can be used for larger surface area. Furthermore, the OLEDs are available in the form of small molecule OLED, polymer LED, passive matrix OLED, and active matrix OLED.

**High brightness LEDs:** This type of high brightness (HB) comprises both inorganic and organic LEDs, and these are broadly employed for lighting applications. In essence, this type of LEDs is nearly similar as organic LEDs; however, these HBLEDs could produce a very high brightness of light output with respect to the OLEDs. For engendering high brightness, these LEDs require a high current and high-power debauchery; as a result, these LEDs were kept on the heat sink for eradicating the liberation of unnecessary heat.

All these three types have found enormous progresses in their light output in recent years. However, the normal quantum yield is exceeding 100 lm/W for the inorganic


soon as Fairchild Optoelectronics instigated manufacturing the low-cost LED devices [10]. In 1976, Thomas P. Pearsall invented a new semiconductor LED materials to be used in fiber optics and telecommunication systems with tremendously bright and high efficiency [11]. In 1979, first blue LED using gallium nitride (GaN) was designed by Shuji Nakamura of Nichia Corporation. By dint of creative techniques, the Fairchild Optoelectronics have made LED into profitable manufactured goods with diversity of usages based on packaging and a planar

2 Light-Emitting Diode - An Outlook On the Empirical Features and Its Recent Technological Advancements

Among the utmost topical technological advancements in lamps lighting devices, LEDs have enormous amount of application niches. Day by day, LEDs are flattering more attractive and more accessible to the common people. For the past few decades semiconductor technology has progressed to greater statures. The result is in the form of smart gadgets and the LEDs

The LED can be lingering further into three major categories are: (1) traditional inorganic LEDs, (2) organic LEDs (small molecule OLED, polymer LED, passive matrix OLED, active matrix OLED), (3) high brightness LEDs. Further, **Table 1** provides the detailed information

**Traditional Inorganic LEDs:** By employing various inorganic materials, the traditional type LEDs are made and therefore called as inorganic LEDs. A number of extensively used LEDs have been fabricated using semiconductor materials like aluminum-gallium arsenide (AlGaAs) and indium-gallium nitride (InGaN). Furthermore, with different doping concentrations in inorganic semiconductor material, the traditional inorganic LEDs are used nowadays. These are obtainable in souk with various sizes, shapes and colors like single color LED,

**Organic LEDs:** Using organic materials, the organic LEDs have been fabricated, which are fictitious from carbon-based polymers and semiconductors. Organic light-emitting diode (OLED) is a thin film of organic compound which consists of a PN junction made by an emissive electroluminescent layer. Further, the emissive layer emits light in Ref. to an electric current and this layer of organic material is positioned among two electrodes. In general, it is realized that as a minimum one of the electrodes must be a transparent one. The organic LEDs are factory-made in the form of thin films; hence, these are given that a small portion for diffusion through which the light engenders, and these can be used for larger surface area. Furthermore, the OLEDs are available in the form of small molecule OLED, polymer LED,

**High brightness LEDs:** This type of high brightness (HB) comprises both inorganic and organic LEDs, and these are broadly employed for lighting applications. In essence, this type of LEDs is nearly similar as organic LEDs; however, these HBLEDs could produce a very high brightness of light output with respect to the OLEDs. For engendering high brightness, these LEDs require a high current and high-power debauchery; as a result, these LEDs were kept

All these three types have found enormous progresses in their light output in recent years. However, the normal quantum yield is exceeding 100 lm/W for the inorganic

which give enhanced illumination with low power ingesting and better life span too.

about the historical developments in LED and OLED [1–55].

surface mounted LED, flashing LED and multicolor LED.

passive matrix OLED, and active matrix OLED.

on the heat sink for eradicating the liberation of unnecessary heat.

process of chip production. [5–8].

3

[15] 2008 The organic materials could be considered

Introductory Chapter: The Impression of Light-Emitting Diodes in Space-Age Advancements…

applications.

[16] 2013 Zhenan Bao et al., have evaluated an

[17] 2015 Consequent researches have been

as small organic molecules in a crystalline phase, or polymers. OLEDs could be widely employed to create display imaging for portable electronic devices like mobile phones, MP3 players, and digital cameras, while conceivable for imminent uses comprise televisions and lighting

http://dx.doi.org/10.5772/intechopen.79375

innovative approach to develop a large-area organic semiconductor thin film with highly oriented single crystalline domains.

technologically advanced on polymerbased multilayer device, plastic electronics, production of novel OLED-based devices

were grown rapidly and so on.

[5–8] 2016 OLED Display Forecasts 2016–2026: The

[5–8] 2017 OLED technology delivers three decades of

[5–8] 2018 Owing to its intrinsic benefits and upcoming prospect OLED has been applied to widespread applications. Nowadays, OLED is widely employed in smart mobile phones, notebooks, smart watches, TV, visual reality (VR) devices, smart wearable devices,

on-board displays, etc.

prospects.

up-to-date development in plastic and flexible display technology analysis. With reference to a deep profundity of the technological analysis and the remaining logjams, IDTechEx has predicted all types of OLED display flea market toward its future

display innovation with high brightness.

[50]

5

[51]

[52]

[53]

[54]

[55]

1971 By employing gallium

nitride the first blue LED was developed by Jacques Pankove.

1972 M George Craford invented the

factors of ten.

1974 Stevenson published a patent,

**1976** Thomas P. Pearsall invented a new semiconductor material having exceptionally bright LED and high efficiency in lieu of usage in fiber optics and telecommunications.

1987 Using AlGaAs (aluminum

1989 Cree Inc. declared the first

gallium arsenide) diodes, the Hewlett Packard has produced the first application, encompasses lighting and usage of light bulbs in vehicles brake light, traffic lights and so on.

commercially accessible blue LED based on indirect band gap silicon carbide (SiC) semiconductor.

first yellow LED using gallium arsenide phosphide (GaAsP) in the diode with an enhanced illumination of red and LEDs with red-orange emission by

reveals a category of gallium nitride (GaN) LED that illuminates light in the visible (violet) region of the spectrum. By employing organic and inorganic phosphors GaN LED may convert lower frequencies (lower energy) with good conversion efficiency. Further he suggests, by employing dissimilar phosphors, all the primary colors may be prepared from this similar basic device."



4 Light-Emitting Diode - An Outlook On the Empirical Features and Its Recent Technological Advancements

[11– 13]

[5–8] 1965 Dow Chemical patented a method of

[9] 1975 Roger Partridge patented the first

the anthracene molecules.

preparing electroluminescent cells using the mechanism of electronic excitation at the contacts between the graphite particles and

observation of electroluminescence from polymer films and his device contained of a thick film of poly(N-vinylcarbazole) equal to 2.2 micrometers located among two charge injecting electrodes and further the work got

Eastman Kodak develop the first practical OLED device. This device utilized a twolayer structure with distinct electron and hole transporting layers such that the light emission through recombination process can happen in the intermediate of the organic layer; this would yield in the enhancement in efficiency and a decline in operating voltage.

1990 J. H. Burroughes *et al.* reported a research on high efficiency green light-emitting polymer-based device by employing poly(pphenylene vinylene) with a film thickness of

> a developer and manufacturer of organic light emitting diodes (OLED) technologies (profitable for phosphorescent-based OLEDs and also respective supple, stacked and transparent OLEDs) and materials in regard to the supplier of services to the display and

and flexible displays were developed using

thin, cost effective displays along with high contrast, color gamut, low driving voltage, and widespread observing angle.

[14] 1994 Universal Display Corporation (UDC) is

lighting industries.

Polymer LEDs.

[5–8] 1998 As an additional advantage the printable

[5–8] 2004 The potential advantages of OLEDs include

100 nm.

consequently published in 1983.

[10] 1987 Ching W. Tang and Steven Van Slyke at

[39]

[40–44]

[45]

[46]

[47]

[48]

[49]

1952 Kurt Lehovec and his research

1955 Rubin Braunstein observed

as well.

1958 Rubin Braunstein and Egnor Loebner, working at Radio Corporation of America (RCA) patented a green LED made from lead antimonide (PbSb) dot amalgamate to p-type Germanium (Ge).

1961 James Robert Biard and Gary

1962 Nick Holonyack (regarded as Father of LED) invented the first practical visible spectrum of red LED with high efficiency by using gallium arsenide phosphide (GaAsP) as a substrate for the diode.

1968 MONSANTO Company

1970 FAIRCHILD Optoelectronics

Pittman invented the infrared radiation from GaAs when electric current is applied and patented a first infrared LED.

becomes the first organization to churn out visible red LEDs based on gallium arsenide phosphide (GaAsP).

(Part of Monsanto Electronic Materials Group) produce commercially successful LEDs.

team have applied for a patent aimed at SiC diodes that emit light. The research team has grown n-type SiC doped with arsenic and then literally acquaints using boron with a beam of electron to produce p-SiC for the junction.

infrared emission generated by simple diode structures using gallium antimonide (GaSb), GaAs, indium phosphide (InP), and silicon-germanium (SiGe) alloys at room (298 K) and at low (77 K) temperature and even in other semiconductor alloys

<sup>5</sup>

[21]

Introductory Chapter: The Impression of Light-Emitting Diodes in Space-Age Advancements…

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7

[22]

[23, 24]

[25]

[26]

High luminous efficiency and, consequentially, low power consumption (67 lm/W, Philips,

the optical wireless (OW) as a capable balancing technology for RF technology has grew newfangled impetus powered by noteworthy utilizations in solid state lighting technology.

a laboratory-result efficacy of 303 lm/W for a white LED lamp (excluding power supply) with a related color temperature of 5150 K at an injection current of 350 mA. The OSRAM Company proclaimed a lamp efficacy of 215 lm/W and a system efficacy (including power supply) of 205 lm/W for a white LED lamp system along with a color temperature of 3000 K.

94 lm/W, Philips, 2010; commercial LED light bulbs with source efficacies >100 lm/W, by multiple manufacturers, 2015).

2011 Elgala et al., discussed about

2014 The Cree Company declared

2014 Zhang et al. showed that

the phosphor-in-glass-based white LED shows not only have remarkable features like heat- and humidity resistance, in addition to that it possess high luminous efficacy of 124 lm/W with a correlated color temperature of 6674 K and a color rendering index of 70.

2015 The commercial, Light Fidelity (Li-

Fi) is designated as a Visible Light Communications (VLC) system running wireless communications itinerant at very extreme haste. The process is by a rapid adoption of indoor and outdoor solid-state lighting will serve as a powerful platform for a new means of delivering data (swaggering speeds of up to 224 gigabits per second approx.) visible light communication (VLC) or Li-Fi.

From 2010 onward

2010;


[5–8]

6 Light-Emitting Diode - An Outlook On the Empirical Features and Its Recent Technological Advancements

[18]

[5–8]

[5–8]

[5–8]

[5–8]

[5–8]

[5–8]

[5–8]

[5–8]

[19, 20]

1991 Masayuki Senoh, scholar

nitride (GaN).

white light.

1994 Using p-n junction gallium

Nichia Corporation.

1995 Using indium tin oxide (InSnO), a transparent contact LED was made by Alberto Barbieri.

1999 PHILIPS LUMILEDS launched power LEDs accomplished of incessant usage by the side of

2002 LUMILEDS made 5 WATT LEDs having a luminous efficacy of 18–22 lumens per watt.

2006 The first LEDs about 100 lumens per watt are manufactured.

> the luminous efficacy about 300 lumens per watt from the visible light and warm light by means

2008 BILKENT University reports

of nanocrystals.

2009 CAMBRIDGE University bangs a method for making siliconbased gallium nitride LEDs.

2010 LEDs of a definite color with a

circumstances.

2010 Solid-state lighting (SSL)

perspective.

is a developing field that potentials enactment features and efficiencies are to use and to harvest enormous extents in terms of energy-economics

gargantuan luminous efficacy of 250 lumens per watt are heretofore being technologically advanced under laboratory

one watt.

1991 A multi-LED-chip methodology

at NICHIA is successful in fabricating p-type gallium

in which the light emitted from three LED chips emitting the three primary colors (red, green, and blue) is mixed to generate

nitride (GaN), the first high illumination blue LED was fabricated by Shuji Nakamura of



properties that could be tuned to emit light covering the visibility spectrum. This is highly important because when these particles are in a confined state, they would have the potential to provide diverse options for color for a while producing an improved white. The uniformity, quality, and tonal color of an LED source desperately add to its allure in usage in commercial production applications. Color stability in fact is one of the more accelerating developments seen recently. Using inorganic packaging associated with flip-chip mounting, the features of the phosphor layer are matched to each chip's individual characteristics. As a result, firms could now suggest white LEDs that have a highly precise prefixed color temperature without the discarding necessary to account for natural changes in color. Another significant advancement in LED technologies has to be done with the material which is in the usage in their production and the resulting efficacy of that production. With one emerging technology, LED lighting could be made with a mixture of organic and inorganic materials. The cumulative effect of this technology is somewhat than typical four or five layers of material would be necessary in producing the product; this new material necessitates just one layer. This vividly lowers the cost of production and produces the manufacturing process relatively easier. This is yielding lower cost for LED light sources while performance continues to enhance. This emerges the new technology to more and more potential applications all over the time [56].

Introductory Chapter: The Impression of Light-Emitting Diodes in Space-Age Advancements…

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9

A recent study of the bactericidal and phototoxic effect of blue LED irradiation revealed that LED irradiation persuades apoptosis by triggering a mitochondria-mediated pathway and reducing the preliminary growth rate of melanoma cells [57]. Oh et al. observed that irradiation with blue LEDs abridged cell feasibility and thus persuaded apoptotic cell death with the mouse A20 and human RAMOS B-cell lymphoma cells [58]. As a potential risk of high energy LED lamps, lighting at night may disturb the body's biological clock, the circadian rhythm. According to the Harvard Health Letter "Blue light has a dark side," the blue wavelengths seem to be the most harmful at night and comprise a large portion in the emission of CFLs

The promulgation of LED lighting has led to prompt progressions in LED lighting technologies over the past few eons across the globe with state-of-the-art scientific advancements; however, evidences besides authenticates that it has been and will spread out to be vitally important in the direction of revolutionary investigation against innovative applications for the societal cause. Among the most important notable advancement in sundry fields of LED and OLED has the roadmap for flexible OLEDs points to the emergence of foldable, rollable displays and the espousal of OLED in smart mobile phones will reach more than 70% by 2020 [54], and this will probably too occur in tablets, laptops, and televisions with subsequently more rapid OLED market share growth. However, the difference of opinion on the bactericidal and phototoxic effect of blue LED irradiation, associated to such parts that need remain to be enhanced for these groundbreaking global improvements on harmful free lighting for the global cause. Thus, studies on peerless LED/OLED hi-tech environs might give way to the

future harbingers of green energy in the upcoming scenario.

and LED lamps [59, 60].

**3. Conclusion**

**Table 1.** Historical developments in LED and OLED.

white-phosphor-based LEDs. Also, it could be found that general lighting applications using OLEDs with a rating 50 lm/W [53–55].
