Welcome to LEDnetics.com, your reference LED store for all lighting and LED devices. In electronics the LED (abbreviation of Light Emitting Diode) is an optoelectronic device that exploits the ability of some semiconductor materials to produce photons through a phenomenon of spontaneous emission when crossed by an electric current. In lighting technology, the LED is a high-efficiency technology that guarantees excellent energy savings.

The commercial strength of these devices is based on their ability to achieve high brightness (many times greater than that of tungsten filament lamps), low price, high efficiency and reliability (the life of an LED is one to two orders of magnitude higher than that of classic light sources, especially under conditions of mechanical stress). LEDs work at low voltage, have high switching speed and their construction technology is compatible with that of silicon integrated circuits.

The first LED was developed in 1962 by Nick Holonyak Jr.. In 2014 the Nobel Prize for Physics was awarded to Isamu Akasaki and Hiroshi Amano from the University of Nagoya and Shūji Nakamura from the University of California, Santa Barbara for research on blue light LED. In the 1990s, LEDs were produced with ever higher efficiency and in an ever-increasing range of colors, also producing white light. At the same time, the amount of light emitted has increased to levels that are competitive with ordinary light bulbs.

Use in lighting

LEDs are increasingly used in the lighting industry to replace some traditional light sources. Their use in domestic lighting, thus replacing incandescent, halogen or compact fluorescent lamps (commonly called energy-saving because they have a higher yield), is now possible with remarkable results, achieved thanks to the innovative techniques developed in the field.

At the beginning of the research, the luminous efficiency, quantity of light/consumption (lm/W), was calculated in the minimum ratio of 3 to 1, then it has improved a lot. The limit of the first devices suitable to be used in this type of application was the insufficient amount of light emitted (luminous flux expressed in lumens). This problem was overcome with the latest generation models, combining the increase in efficiency with the technique of having die matrices in the same package connected in series and parallel or making the matrix directly in the substrate of the device. The efficiency of current devices for professional and civil use is more than 120 lm/W, but it drops to around 80 lm/W in warmer light devices. For example the Cree CXA3050 has Ra>90 and 2700K. A 60 W incandescent lamp powered at 220V, emits a luminous flux of about 650 lumens.

As a comparison, an incandescent lamp has a luminous efficiency of about 10-19 lm/W, while a halogen lamp about 12-20 lm/W and a linear fluorescent lamp about 50-110 lm/W. A lower ease of use in functional lighting compared to traditional lamps is constituted by the characteristics of power supply and dissipation, which strongly affect the light output and duration over time. However, it becomes difficult to identify direct relationships between the various sizes, between which also comes into play a further parameter, namely the beam angle of light emission, which can vary from about 4 degrees to over 120 degrees, however, can be modified through appropriate lenses placed frontally.

LED manufacturers are manufacturers of semiconductors, silicon factories, while bulbs are mainly produced by other manufacturers. There is, therefore, a certain delay between the date of placing a new LED device on the market and the availability on the market of a bulb that uses it.

The advantages of LEDs from a lighting point of view are:

  1. Operating time (high emitting LEDs reach about 50,000 hours with a loss of luminous flux of 10% max);
  2. reduced maintenance-replacement costs;
  3. high efficiency (when compared to incandescent and halogen lamps) Light without IR and UV components (high efficiency: no part of the energy transformed into light is outside the visible spectrum);
  4. easy realization of efficient plastic optics;
  5. flexibility of light spot installation;
  6. possibility of a strong spot effect (near-point source);
  7. safe operation because of very low voltage (normally between 3 and 24 Vdc);
  8. cold start (down to -40 °C) without problems;
  9. absence of mercury;
  10. possibility to create luminaires of new shape due to the reduced dimensional impact;
  11. possibility to adjust the luminous intensity (only on some models);
  12. less heat generated in the environment compared to other lighting technologies.

Bestselling Products

 

DAYBETTER Led Strip Lights 32.8ft 5050 RGB LEDs Color Changing Lights Strip for Bedroom, Desk, Home Decoration, with Remote and 12V Power Supply

  • Strong self adhesive: The led strip lights has a stronge self adhesive so they stick very well on TVs, cars, cabinets and walls; Please test the led strip lights before installation, every roll lights has one connector to link with controller box, so they should be attached in parallel, not in series
  • Colorful and durable: The infrared remote can adjust multiple colors, including rgb, white, 16 other colors and their brightness; With 6 dynamic modes (auto, flash, jump3, jump7, fade3, fade7) and 2 speed modes (quick, slow) by remote, you can make the light strip show varieties of different color changes; Use the DIY buttons to save 6 colors if you like
  • Cuttable and linkable: Can be cut every 3 LEDs along the cutting marks if you don't need such a long lights or you could extral connectors to extend the lights for your bedroom, TV, desk, computer indoor
  • Remote contol: You can use the infrared remote control to remotely control the light strip to suit the mood of the room easily; You can set it according to different scenes until you are satisfied
  • Widely use: The led lights are suitable for bedroom, kitchen, cabinet, car, living room, party or wedding
 

Tenmiro 65.6ft Led Strip Lights, Ultra Long RGB 5050 Color Changing LED Light Strips Kit with 44 Keys Ir Remote Led Lights for Bedroom, Kitchen, Home Decoration

  • Ultra Long Strip Lights: 65.6ft led strip lights are long enough to reach around your entire room and light the whole place up, cuttable design allows you to adjust the length of led lights whatever you like, for bedroom, living room, cabinet, party, christmas, etc
  • Multi Color and Diy: Led lights colorful and durable, the brightness of the lights strip can be adjusted and offer millions different colors and 8 lighting modes(jump, fade, flash etc) by 44keys remote
  • Easy Installation: Complete led light strip kit Including 4 rolls of 16.4ft led light strips, power adapter, 44keys remote Control, controller, instruction manual, led strip lights installation accessories(4 pin connectors, gapless solderless connectors, back adhesive hooks), no need for other devices, self adhesive tape easy to install
  • Cuttable and Linkable: The led lights can be easily cut and linked with other strip led lights, which can be cut every 3 leds along the cutting marks, you can also customize the length of the led lights, while arrows of the lights should be faced to each other when connecting, if using solderless connecto then while '+12V' should be faced to each other when connecting
  • Multiple Scenes Available: Rgb led strip lights is a suitable house ornament, transforms your home, kitchen, ceiling, back of tv, desk, stairs, bar and more with color changing lights
 

50ft Led Strip Lights, Keepsmile 5050 RGB Color Changing Led Light Strips, Led Lights for Bedroom, Kitchen, Home Decoration

  • LED Strip Lights with Remote: 50ft led strip lights are long enough to reach around your entire room and light the whole place up. For bedroom, living room, cabinet, party, christmas, etc
  • Multi Color and Diy: Led lights colorful and durable, the brightness of the lights strip can be adjusted and offer millions different colors and 8 lighting modes(jump, fade, flash etc) by remote
  • Cuttable and linkable: Cuttable design allows you to adjust the length of light strip however you like, if you don't need such a long lights, you can be cutted between every 3 LEDs. Also could extral connectors to extend the lights for other places
  • Quick and Easy Installation, fully equipped accessories, include LED strips, a AC Power Adapter, a IR remote Control, a controller, a Instruction Manual, a led strip lights installation accessories bag, no need for any other devices
  • Multiple Scenes Available: Rgb led strip lights is a suitable house ornament, transforms your home, kitchen, ceiling, back of tv, desk, stairs, bar and more with color changing lights
 

Daybetter 5050 RGB Flexible Color Changing Remote Control Led Strip Lights - 65.6ft

  • Long enough to decore your entire room; You don't need to connect additional light strips with connectors to adjust the lenght whatever you like
  • Multicolor changing: You can easily adjust rgb, white, 16 other colors and their brightness; With 6 dynamic modes (auto, flash, jump3, jump7, fade3, fade7) and 2 speed modes (quick, slow) by 44keys remote, you can make the light strip show varieties of different color changes; Use the diy buttons to save 6 colors if you like
  • Remote contol: Using the 44-key infrared remote control, you can easily use the remote control to adjust the color and brightness to suit the mood of the room
  • Cuttable and linkable: The lights strip can be easily cut every 3 leds along the cutting marks; You can link it with other strip led lights by additional connectors
  • Easy to install and use: With strong adhesive and flexible design, the strip lights can stick on any dry and flat surface; Suitable for decorating your bedroom, living room, ceiling, upstairs, kitchen, back of tv, desk
 

MINGER LED Strip Lights 16.4ft, RGB Color Changing LED Lights for Home, Kitchen, Room, Bedroom, Dorm Room, Bar, with IR Remote Control, 5050 LEDs, DIY Mode

  • Multicolor changing: the RGB LED strip lights kit has not only RGB(Red, Green, Blue), 16 multicolored options, but also DIY selection
  • Remote control: 44-key IR remote allows you to choose colors, adjustable brightness and multiple lighting modes to fit room mood. (remote range: 10m)
  • Bright LED Lights: it features 150 bright 5050 LEDs that easily light up a room, bedroom, dorm room, kitchen countertop. Suitable for birthday party, home gathering
  • Easy to install: with back adhesive and flexible strip design, it can stick on any dry and flat surface. Note: use the packaged adapter to meet working power requirement
  • Notice for using: please do not roll up when using it to avoid whole strip getting overheated. The strip is non-waterproof for indoor use only
 

Fahren H11/H9/H8 LED Headlight Bulbs, 60W 10000 Lumens Super Bright LED Headlights Conversion Kit 6500K Cool White IP68 Waterproof, Pack of 2

  • 300% Brighter Than Halogen Top Automotive Grade LED chips with 60W, 10,000LM per pair, 6500K cool white. Super focused beam pattern design provides wider and farther lighting range which is 3 times brighter than your original halogen bulb.
  • Over 5,0000 Hours Lifespan Whole aviation aluminum body, unique hollow carved heat sink design and 1,2000RPM turbo cool fan provide super cooling ability, which ensures a longer lifespan up to 5,0000 hours.
  • 10 Minutes Easy Installation Almost 1:1 mini design same as halogen, perfectly fit into your housing and factory sockets without any modification, just plug and play.
  • CAN bus Ready for 98% Vehicles Our bulbs work with 98% of vehicle's computer system without error, while some sensitive models of Ford, Jeep, Dodge, Ram, Volvo, Lexus, Chrysler, Mini and etc may require additional CAN bus decoder to be installed.
  • Note The filter system may not be 100% accurate or up to date, please check your owner's manual or the part number on your original bulbs to confirm the bulb size. Refer to "how to pick the right bulb size" in our Product Description.
 
LED Strip Lights, Tenmiro 32.8ft Led Music Sync Color Changing Light with 40keys Music Remote Controller, Led Lights for Room, Bedroom, TV, Party
16,845 Reviews

LED Strip Lights, Tenmiro 32.8ft Led Music Sync Color Changing Light with 40keys Music Remote Controller, Led Lights for Room, Bedroom, TV, Party

  • Music sync color changing lights, sensitivity adjustable microphone, which creating romance, relaxation, party ambiance with music, lights color will change with the music beats or your microphone, there are 4 music modes to choose
  • Multifunctional, ir remote controller with 40 keys, including 20 different light colors, 4 brightness adjustment, 4 music modes, 4 timing off levels, 6 dynamic light modes, and can simulate the color change of sunrise and sunset
  • Easy installation, all in one kit, comes with an ac adapter, a remote control receiver, plug and play, the arrows should be connected on the same line, self adhesive tape can be fit on any dry and flat surface, flexible to install anywhere you want, it can be cut between every 3 leds, no need to connect it to phone or download apps, easy to use
  • Widely use, color changing led strip light is a house ornament, transforms your living room, bedroom, home, kitchen, ceiling, back of tv, desk, stairs and more with colored lights, especially for holidays and events like christmas, halloween, parties, and more, suitable for indoor use
  • Timer, use retome to set the timer, which allows the lights work for your schedule, there are four times for you to choose, you can set 1H, 3H, 6H, 9H, to automatically turn off the led light strip, you can adjust the brightness, let The soft light accompanies you to sleep
 

Led Zeppelin IV

  • Amazon Prime Video (Video on Demand)
  • Bob Carruthers (Director)
  • English (Playback Language)
  • English (Subtitle)
 

Volivo 65.6ft Led Strip Lights, RGB Color Changing Led Lights for Bedroom with 44 Keys Remote for Room, Party, Home Decoration

  • Durable Light Strips: Our led light strips are made of 5050 rgb led lights with multi colors; The brightness is adjustable, you can set according to your need; Long lasting for 50000 hours lifespan
  • Create Colorful Atmosphere: The 44 keys ir remote controller comes with 20 color options, 6 diy color keys and 8 dynamic modes; You can set the led lights strip to different situations atmosphere according to your mood
  • Long and Widely Used: Our led lights is suitable for your bedroom, room, TV, kitchen, stairs, porch, dining room, ceiling, party and home decoration; The color changing led strip lights are safe for children to use, energy saving, and the room lights is environmentally friendly
  • Easy to Install: The led strips are made with strong adhesive, which makes it stick stronger on dry and smooth surface; You don't need to worry about falling off; It also can be cut between 3 leds along the cutting marks, without damaging the rest led light strip
  • Safe and Professional: The lights for room use double layer copper board and the led room lights meets the safety standard; Power supply is under safe value for adults and kids
 

Daybetter Led Lights Color Changing Led Strip Lights with Remote Controller-60ft

  • Double adhesive:Our led strip lights can install with adhesive
  • 60 Feet led lights are enough long to cover the whole place;use for bedroom, living room, kitchen
  • Easy Installation:The strip light is easy to finish the big space decoration
  • Cuttable and linkable:The lights strip can be easily cut every 3 leds along the cutting marks; You can link it with other strip led lights by additional connectors
  • Color changing strip lights: The led strip lights provide16 multicolored options; you can choose your favorite color to decorate your room
 

HRDJ Led Strip Lights 65.6ft, Music Sync Color Changing Led Lights for Bedroom 5050 SMD RGB Led Light Strips with Remote App Control Led Lights for Room Party

  • 65.6ft smart led strip lights: light strips via app, remote control and controller; with the App, you can choose to control 16 million colors; 28 dynamic modes like flashing,breathing,gradient
  • Music sync led lights: the lights strip has smart music mode, sensitivity adjustable microphone, lights color will change with the the rhythm of the sound and music, which creating romance, relaxation, magical and interesting atmosphere for your party
  • Timing function: Led lights bedroom with the smart app, pre-setting the appropriate time and suitable color to make it turn on/off automatically, you wake up in romantic lighting every morning
  • Easy Installation: 65.6ft LED light strips just clean the adhesive surface and paste, the led can be easily cut every 3 leds along the cutting marks
  • Multiple scenes available: rgb led lights Led strip lights for bedroom kitchen porch computer desk and living rooms tv backlight parties, it will also be a lovely gift for your friends
 

SEALIGHT Scoparc S1 H11/H8/H9 LED Headlight Bulbs, 12000 Lumens Low Beam, 6000K Bright White, Halogen Replacement, Quick Installation, Pack of 2

  • Increase your confidence while driving at night: The H11 LED headlight bulb is 1.5x brighter than halogen bulbs, with pure white color light allowing you to see further and clearer for safer driving
  • Save installation time: No tools needed to replace the lower profile H11 LED bulb. Although the factory housing has a dust cover or there is limited space on the passenger side, only needs 10 minutes
  • No more frequent replacements: The SEALIGHT S1 LED headlight bulbs strike a perfect balance of performance and lifespan, the bulb can last for 20 years even you drive for 6 hours at night every day
  • Fanless design: Without fan, there is no chance of fan failure. The H11 led lights features smart cooling, it also doesn’t have annoying noise even you have sensitive ears, you can enjoy your driving
  • Won’t blind other drivers: The H11 LED headlight low beam bulb has a perfect beam pattern to ensure the safety of both drivers, with no glare or dark spots reduces your driving stress and exhaustion
 

Phopollo Led Lights 65.6ft Long Led Strip Lights for Bedroom Color Changing Luces Led para Decoracion Habitacion RGB DIY Color Option with Power Supply and Remote

  • Long enough to jass up your entire big bedroom and light the whole place up
  • 20 color options adjust brightness, choose colors and light modes
  • The strip lights can be cut off every 3 leds along cutting marks to any length you want without damaging,but without conectors in the pakcage
  • Led strip lights with remote have a strong adhesive tape
  • 12 volt working voltage ,if it does not light up .please check your connection is correct or not
 

Govee LED Strip Lights, 32.8FT RGB LED Lights with Remote Control, 20 Colors and DIY Mode Color Changing LED Lights, Easy Installation Light Strip for Bedroom, Ceiling, Kitchen (2x16.4FT)

  • Colors That Energize: The LED strip lights are packed with traditional RGB and 16 other colors. You can enjoy 6 additional DIY colors for more creative freedom. Jazz up your romantic dinners or Christmas parties with vibrant lighting.
  • Dual Control: Manage your lights easily from the comfort of your couch with a remote control range of 32.8ft. With the control box, you can power the lights on/off, adjust brightness, or change colors at the touch of a button.
  • Adjustable Brightness: 6 brightness levels allow you to alter the strip lights from warm to bright. 5050 LEDs and a 50,000-hour product lifespan ensure you vivid, long-lasting lighting, great for your TVs, bedroom, and kitchen.
  • 32.8ft LED Lights: With 2 rolls of strip lights (16.4ft each) stretching to a total length of 32.8ft and 300 LEDs, you'll find it easy to illuminate larger spaces with bright, colorful lighting during the holidays, parties, or movie nights.
  • Easy to Install: Use the strong adhesive to install the lights to any dry, clean surface, or the clips for further reinforcement. DIY fans will enjoy our cuttable design, allowing you to trim the strips to your liking (4-pin connectors not provided).
 

Led Strip Lights, Jadisi 65.6ft Music Sync RGB Lights Strip, SMD5050 Color Changing with Bluetooth Controller + 24 Key Remote Control LED Lights for Bedroom, Bar, Party, Home Decoration(4X16.4ft)

  • ✅[Triple Control Method]:RGB LED light strip can create multiple smart music modes through IR remote control and APP (for iOS/Android), 65.6ft (4x16.4ft) RGB LED light strip. There are more than 16 million colors to choose from in the APP. You can DIY your favorite color to decorate your room.
  • ✅[Music Mode and Timer]:There is a built-in microphone that will sync with any music coming out of phone speaker or other speaker in room and dance the lights along with beats of music (or hands claps). There are more than 16 million colors in the APP, and you can plan to turn the light strip on or off at a specific time to wake up bright colors.
  • ✅[Strong Stickiness]:The product includes 8 clips, 8 LED Strip hooks with Strong 3M Back adhesive double-sided tape on the back of these LED tapes to enhance strength, 1 remote control receiver 3M Back sticker and exclusive 4-pin 10mm corner-friendly LED strip connectors x 3 .Due to its strong adhesion, you can also stick the adhesive strip on an irregular surface without falling off. All 4 LED have a cutting line, you can do DIY without damaging other lights.
  • ✅[Easy to Install and Widely Used]:Our light strips are environmental friendly and harmless to human health. Providing a simple way to start designing your connected home, very suitable as a backlight for mood lighting or interior decoration, such as rooms, beds, TVs, kitchens, bars, At Christmas, birthdays and other parties. (Not waterproof!)
  • ✅[Excellent Customer Service]:You will get: 4 x 16.4 FT LED light strips, 1 x remote control receiver, 1 x 24 key remote control (batter is included), 1x AC/DC adapter, 1 x user manual and some accessories! Any Question, Please click GET HELP WITH ORDER under your order ID or contact us via email, We will give you a satisfactory solution.
 

DAYBETTER Smart Led Lights 65.6ft, App Controlled Led Strip Lights Kits with 24 Keys Remote, Timer Schedule Led Lights Strip, Color Changing Led Lights for Bedroom Party Kitchen

  • App control: Take control of your lighting by connecting the led strip light to your phone through the smartphone app; with the app you can control over 16 million colors, turn your lights on/off, set the mood with the dimmer function, or choose your favorite color effects, diy lighting at your fingertips
  • Smart led lights sync with music: With built-in, high sensitivity microphones, our smart led light strip sync to the beat of your music, it can even respond to your voice
  • App timing and music functions: Led lights for room has timing/countdown function, you can set the time and let the led strip lights for bedroom automatically turn on and off; turning on the music mode, led strips will change colors sync to music, bringing party effects; note: use music mode, please make sure you have downloaded music in mp3 format to your playlist, ios user please download mp3 format music from your computer iTunes account then sync the music to your phone
  • Easy to install and use: Our rgb led strip is easy to cut, It can be cut every 3 leds along with the cutting marks, without damaging the rest of the strip; our flexible pcb strips can be bent to different patterns, our led light strips for bedroom has a working voltage of 12V and are equipped with short circuit protection
  • Strong self-adhesive: Strong self-adhesive makes the lights strip easy to mount to your walls, under your bed or cabinets, behind your tv, and pretty much anywhere you’d like
 
65.6ft Led Lights for Bedroom dalattin Led Strip Lights Color Changing Lights with 44 Keys Remote,2 Rolls of 32.8ft
5,125 Reviews

65.6ft Led Lights for Bedroom dalattin Led Strip Lights Color Changing Lights with 44 Keys Remote,2 Rolls of 32.8ft

  • 65.6feet Led Lights:Long enough to reach around your entire room and light the whole place up
  • Cuttable and Linkable:Led lights can be cut between every 3 LEDs along the cutting marks;Note that our products do not include connectors
  • Self Adhesive: 3M self adhesive tape of led lights can be flexible stuck on any dry and flat surface
  • Widely Use:Suitable for living room,kitchen,cabinet,porch,bar,bedroom,party,Christmas or wedding
  • Before you want to stick the light,please confirm its position to avoid damaging your wall
 

10Packs 4-Pin RGB LED Light Strip Connectors 10mm Unwired Gapless Solderless Adapter Terminal Extension for SMD 5050 Multicolor LED Strip (10Pack 4PIN RGB Connector)

  • ❤Easy to Use:Compatible with 0.39inch / 10mm Wide SMD 5050 RGB Flexible LED Strips,
  • ❤Solderless couplers for 10mm waterproof RGB LED strips only Pins pierce the strip from behind to make a connection without compromising the silicone Suitable for standard density strips only .
  • ❤Quick Splitter Connection and A Solderless Quick Snap Down Solution.These are designed specifically for use with waterproof strips that have a silicone coating.
  • ❤Pins of led strip:4 pin Led strip .width:10mm Working Tempreture:0-50°C Storage temp: -20~60°C
  • ❤Product Guarantee We offer a 12MONTHS return policy and a one year warranty. Buy with confidence!
 

Bathebright led Strip Lights 16.4ft, RGB Color Changing for Bedroom, Room, Kitchen, Ceiling with 44 Keys Remote Control

  • Color Changing: This led lights strip has 20 colors, 8 lights changing modes, 6 DIY settings
  • Remote Control: The rgb lights come with 44 keys remote, you can adjust the brightness and lighting modes and the speeds easily
  • Strong Adhesive: The strip lights with strong adhesive , just peel off the back layer and stick to the clean and dry surface firmly
  • Where to Use: The lights strip can be used in bedroom, back of TV, kitchen, door, under beds
  • Packing List: 1x roll 16.4 feet led strip lights, 1x 12v power supply, 1x remote control, 1x controller box, 10x fixing clips, 1x instructions manual

History of LED

The first devices

In 1907, at the Marconi Company laboratories, Henry Joseph Round discovered the effect of photoluminescence using silicon carbide (SiC) and a radio component. Exactly twenty years later, Oleg Losev published a theory in Russia, where he claimed to have created the equivalent of a rudimentary LED; although the publication was also published in the German and British Empires, for decades there were no practical applications for his invention.

In 1936, at Marie Curie’s laboratories, physicist Georges Destriau obtained electroluminescence (which he himself called “Losev light”) by encapsulating zinc sulfide (ZnS) in a container in which he applied an alternating electric field. Three years later, the Hungarians Zoltán Bay and György Szigeti patented a silicon carbide device capable of emitting white or white light tending to yellow or green, depending on the impurity present. In 1951, Kurt Lehovec, Carl Accardo and Edward Jamgochian understood for the first time the real functioning of a diode capable of emitting light, using silicon carbide crystals and as an electrical source a battery and a pulse generator, comparing in the following two years the results obtained with others obtained by varying the type of crystals and their purity.

In 1955, Rubin Braunstein, of the Radio Corporation of America, obtained infrared light emission from gallium arsenide (GaAs) and other semiconductors, such as gallium antimonide (GaSb), indium phosphide (InP) and silicon germanide (SiGe), both at room temperature and 77 kelvin. Two years later, he demonstrated that rudimentary devices could be used to communicate over short distances; such devices would then be used in optical communications.

In September 1961, at Texas Instruments, James R. Biard and Gary Pittman discovered that a tunnel effect diode with gallium arsenide substrate was capable of emitting infrared light with a wavelength of 900 nanometers. In October, they demonstrated the effectiveness of communication between this diode and an electrically isolated photodetector. On August 8, 1962, Biard and Pittman applied for a patent entitled “Semiconductor radiant diode”: a diode with a p-n junction and diffuse zinc, with the cathode spaced to allow an efficient emission of infrared light when the device is in the so-called direct polarization. After receiving applications also from General Electric, Radio Corporation of America, IBM, Bell Laboratories and MIT Lincoln Laboratory, the U.S. patent office gave the two inventors the patent for the infrared light emitting diode in gallium arsenide, the first real LED for practical use. Immediately afterwards, Texas Instruments launched a project for their realization and, in October 1962, the company announced the commercial production of LEDs with gallium arsenide crystalline structure capable of emitting light with a wavelength of 890 nanometers.

The first emission LED in the visible spectrum was developed at General Electric by Nick Holonyak Jr. who published an article on December 1, 1962. Having obtained an LED with emission in the visible spectrum, then the realization for the first time of an electronic component capable of emitting light perceptible by humans, made Holonyak to the public eye as the “father” of the LED. In 1972, George Craford, a former student of Holonyak, created the first yellow light LED and improved the light output of red and red-orange LEDs by a factor of ten. Four years later, T. P. Pearsall created the first high efficiency and luminescence LED, resulting in new semiconductor compounds specifically suitable for fiber optic transmissions.

Mass Use

The first commercial LEDs were used to replace some incandescent and neon lamps, for seven-segment displays, optoisolators, expensive laboratory equipment first and then to switch to calculators, televisions, radios, phones and more. Both infrared and visible LEDs were still extremely expensive, however, in the order of two hundred dollars each, so they were used relatively little. Starting in 1968, Monsanto Company was the first in the world to start mass production of LEDs in the visible, using gallium, arsenic and phosphor to make red LEDs suitable as indicators (arrows, numbers, etc.). Later, other colors began to be available and LEDs began to appear on various other equipment and devices. In the seventies, LED devices were produced and marketed for less than five cents each. These diodes were made from semiconductor chips manufactured with the planar growth process devised by Jean Hoerni at Fairchild Semiconductor. The combination of this process with innovative encapsulation methods enabled Fairchild, under the leadership of optoelectronics pioneer Thomas Brandt, to significantly reduce production costs, opening the way for all other manufacturers.

The first LEDs had a metal casing similar to that used for transistors, with a glass lens for the passage of photons. Subsequently, they switched to transparent plastic casings, of various shapes and often with colors corresponding to the color of the light emitted. In the case of infrared LEDs, the tint can be applied to achieve the opposite effect, i.e. blocking the visible light output. Specific encapsulations are then designed for the efficient heat dissipation of high power LEDs.

The advent of blue LEDs

The first blue-violet LED was made with gallium nitride (GaN) doped with magnesium at Stanford University in 1972 by Herb Maruska and Wally Rhines, PhD students in materials science and engineering. The previous year, a former colleague from Maruska, Jacques Pankive, together with Ed Miller, at the Radio Corporation of America, obtained for the first time blue electroluminescence through gallium nitride but with zinc doping: from it, then, they obtained the first gallium nitride diode to emit green light. In 1974, Maruska, Rhines and Professor David Stevenson received the patent for their invention. In the 1970s, no practical use could be found for gallium nitride diodes doped with magnesium, and research slowed down, only to return decades later with the development of blue LEDs and laser diodes.

In August 1989, Cree was the first company to market blue silicon carbide LEDs, so with an indirect prohibited band that makes the device very inefficient. Also in the late 1980s, key milestones in the epitaxial growth of gallium nitride with doping of acceptors brought optoelectronic devices into the modern era. On this basis, in 1991 Theodore Moustakas, of Boston University, devised a method for the production of high luminescence blue LEDs through a two-step process, obtaining a patent six years later.

In 1993, with a growth process similar to that of Moustakas, Shuji Nakamura, from Nichia, also produced a high luminescence blue LED. Both Moustakas and Nakamura received a patent and this generated confusion as to who was the real inventor of the blue gallium nitride LED, in fact Moustakas discovered his method first but his registration at the patent office was later than Nakamura’s one. The possibility of producing blue LEDs on an industrial scale opened up the development of new technologies and applications in the following decades, so much so that Nakamura received the Millennium Technology Award in 2006 and in 2014, together with Hiroshi Amano and Isamu Akasaki, the Nobel Prize for physics.

In parallel, in Nagoya, Isamu Akasaki and Hiroshi Amano himself worked on the development of a method to grow gallium nitride on a sapphire substrate, doped with acceptors, and on demonstrating the increased efficiency of LEDs made with this process. In 1995, at the University of Cardiff, Alberto Barbieri studied the efficiency and reliability of high luminescence LEDs with a structure formed by layers of aluminum phosphide, gallium and indium (AlGaInP) and gallium arsenide (GaAs), with a “transparent contact” that is a transparent film of indium tin oxide (also known as ITO, Indium tin oxide).

Between 2001 and 2002, methods of growth of gallium nitride on silicon were successfully demonstrated and, in January 2012, Osram found a way to produce industrial quantity LEDs in indium gallium nitride (InGaN) grown on silicon substrates. At least until 2017, manufacturers used silicon carbide substrates, although the most common one remained sapphire because it has properties very similar to gallium nitride, which reduces the formation of defects in its crystalline structure during growth.

At the end of the decade, Samsung and the University of Cambridge carried out research on gallium nitride LEDs grown on silicon substrate, initially followed by Toshiba, but then stopped the research. Some opted for epitaxial growth by nano-printing lithography, while others opted for multi-layer growth to reduce the differences between crystalline structures and thermal expansion rate, in an attempt to avoid chip breakage at high temperatures, decrease heat emission and increase light efficiency.

White LEDs and use in lighting

White light can be produced by using different colored LEDs together: one red, one green and one blue; however, the color quality will be low because only three narrow bands of the visible spectrum are used. A better method is to use a high efficiency blue LED, using the properties of phosphor to produce white light. In these devices, when the blue LED light hits an overlying layer of phosphor, doped with yttrium garnet, aluminum (YAG) and cerium (Y3Al5O12:Ce), it produces a yellow fluorescent light: the overall effect of blue and yellow light has a very wide bandwidth and is therefore perceived as white light by the human eye, with a higher color rendering index than white obtained by combining red, green and blue LEDs.

As with its predecessors, the first white LED was expensive and inefficient. However, the improvement in light output grew exponentially: the latest developments and research have been carried out by Japanese, Korean and Chinese companies, such as Panasonic, Nichia, Samsung and Kingsun. The trend of this growth is defined by Haitz’s Law (pictured), which takes its name from Roland Haitz.

The light emission and efficiency of blue-violet LEDs grew and at the same time the cost of the devices fell, allowing to produce white LEDs with relatively high power, potentially suitable to replace traditional lighting.

In the decade of the two thousand, experimental white LEDs produced 303 lumens per watt of electrical current input, with a life span of up to one hundred thousand hours, although those on the market stopped at 223 lumens per watt. Compared to an incandescent lamp, it was therefore obtained a substantial increase in electrical efficiency at the same price and, sometimes, at an even lower cost.