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

 

Led Zeppelin IV

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

Led Zeppelin IV (Remastered Original Vinyl)

  • Side 1
  • 1. Black Dog
  • 2. Rock And Roll
  • 3. The Battle Of Evermore
  • 4. Stairway To Heaven
 

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 however 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
 

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
 

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
 

Daybetter SMD 5050 App Control Bluetooth Led Strip Lights- 50ft

  • Sensitive microphone,this lights strips color changing sync to music
  • This 50 feet led strip lights support app control and 24keys remote controller, support to change lights color and modes
  • With timer function, this led light strips allow you to preset time to turn on or turn off led lights and change color at certain times
  • With adhesive tape, this color changing led light strip fit for place as long as it is dry, clean and smooth
  • This led strip lights with short circuit protection,and its working voltage is 12volts
 

Led Lights Smart Led Strip Lights Ultra Long 65.6ft Music RGB

  • 65.6 feet
  • Timing function
  • Quick and easy installation
  • Music and mic mode function
  • Wide range use
 

Charkee Led Lights for Bedroom 50ft, 2 Rolls of 25ft Led Light Strips with Remote and Power Supply for Bedroom, Room, Kitchen, Decoration

  • Led lights for bedroom 50 feet, 2 rolls of 25 feet, bring you a bright lighting experience and provide primary 44 multicolored options for you
  • Led lights can be used for decorating your room, bedroom, living room, upstairs, kitchen, and desk
  • Because of the adhesiveness of led tape, we recommend that you test the product before decorating
  • The lights also have diy function to make you set your lighting show for different atmosphere
  • The led strip lights are easy to install, you can decorate your room and have a lighting experience
 

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
 

Daufri LED Strip Lights 32.8ft, Waterproof 5050 RGB Color Changing LED Lights for Bedroom, Kitchen, Party, Home Decoration, with 44 Keys IR Remote Controller and 12V Power Supply

  • LED Strips: LED strip lighting has 300 RGB 5050 SMD Leds in 32.8 feet(2x16.4ft) with dimmer and brightness controls, and with 44 key IR remote controller and 5A 12V power adapter. The lights strip can be used indoor or outdoor decoration.
  • Easy Installation & Use: Led rope lights can be cut between every 3 leds.With strong blown-sponge, it can be easily installed the light strips on any dry and flat surface you want.
  • Multi-Color & DIY: LED tape strips lights set will change colors and speed automatically and periodically. It has not only RGB (Red,Green,Blue),20 multicolored options, but also has DIY selection to create your great led mood lighting.
  • Good & Full Material: Using double layer copper on PCB board to keep the mixed colors more even. LED IR remote controller has over charging, short circuit protection and memory function. Power supply makes sure the safety for adults and kids.
  • Energy Saving and Safe- Low Power Consumption. High safety performance. The working voltage is 12V. Extremely low heat. It is touchable and safe to children.
 

Daybetter 5050 RGB Infrared Remote Control Color Changing 50ft Led Strip Lights

  • 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
  • Remote control: You can easily use the remote to adjust the colors and brightness to suit the mood of the room
  • Colorful light: Rgb, white, 16 other colors, adjustable color temperature and dimmable light; Use the diy buttons to save 6 colors if you like
  • Cuttable and linkable: Can be easily cut every 3 leds along the cutting marks, or extended up, to the size to you like; Extensions are not included
  • Widely use: Easy to set on most indoor surfaces, such as bedroom, kitchen, cabinet, car, living room, party, or wedding
 

50ft Led Strip Lights, smareal Led Lights Strip Music Sync Color Changing Led Strip Lights App Control and Remote Led Lights for Bedroom Party Home Decoration

  • App Control Kit,Controlling the Led strip lights via App,24key remote control and controller,strip lights has a smart music mode,lights color will change with the the rhythm of the sound and music.create a romantic,gorgeous,interesting,magical atmosphere for your party
  • Timing Led Lights Strips,You can adjust the lights strip brightness to suit the various places,Led strip lights have memory function,when the strips are used again,they remember the last mode settings without setting again,with the smart App,you can experience the timing function,automatically turn on and off at preset time,28 Dynamic Modes can be chosen,you can also Diy your unique color
  • Multiple Scenes Available,Led strip can be used for decorating your Dining room,Bedroom,Upstairs,Porch,Computer,desk,Corner,bar,meeting room and Living rooms,especially great for Holidays and Events like Christmas,Halloween,Parties and more
  • Easy to Use and Install,Fully equipped accessories,it comes with 3 reel of 16.4ft Led light strip,an AC Power Adapter,a 24Key remote Control,a controller,a Adhesive Pad,2 pcs 4Pin Connectors,4 Buckles and a Instruction Manual.easy to install
  • Purchasing Experience,Please carefully read the user manual carefully before strip lights using.if you have any questions,please don't hesitate to contact us
 

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).
 

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
  • Led strip lights with remote have a strong adhesive tape
  • 12 volt working voltage
 

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
 

LED Strip Lights,50Ft Color Changing LED Strip Lights Music Sync,Bluetooth App Controlled Remote,5050 RGB LED Rope Lights 16Million color,Sensitive Built-in Mic,LED Lights for Bedroom Kitchen TV Party

  • 📱【Multiple Mode to Control Your Lights】- Control the LED strip lights via(APP+ IR Remote+Mic+3 buttons ) ① APP Control:Download the app"Ehome Light"( Google Play and iOS App Store) Adjust brightness,color changing led strip lights.② Music and Mic Functions :Built-in mic,LED rope lights will pulsate and change colors along with the environmental sound and music ③ IR Remote:20-key 4 music mode to control the light strip ④ 3-button controller:Through 3 keys switch between static, dynamic,MIC mode
  • 🕜🎵【Timer Sunrise&Sunset,Mic and Music Functions】- ① Schedule your LED Strip lights to turn on or off at specific time. Wake up to vibrant colors. ② Microphone mode,Comes with sensitive built-in mic in the controller switch, LED rope lights will change colors along with the environmental sound and music.③ Music mode,play local music through mobile phone , turn to the music model,you’ll see the color changing LED strip lights with the music
  • 🌈【Dimmable LED Strip lights】- (2 rolls 25ft color changing led strip lights)Super bright and high-quality LED rope lights,5050 RGB 450LEDs,16 millions colors.It can be cutted between every 3 beads, so you can adjust them to the right length.Led lights more than 50000 hours service life. UL listed power cord that lasts long, more durable and safer.
  • 🔧【User-friendly 】- Plug and Play,APP Group Management;Whe control several LED strip lights at the same time through the APP, please create several groups to control them separately,Suitable for bedroom,projector screen,kitchen, cabinet, car, living room, party, Christmas or wedding,dorm rooms, bars and shops,stairs,With Strong 3M Back adhesive for planning the route of your LED strip lights or fix the bent LED rope strips at corners.
  • 💗【Reliable After -Sales Service】- These are Upgraded high-brightness LED units soldered on dual-layer copper circuit strips,color changing LED Strip lights have a 18 months warranty. If you still have any issues during installation, defective items, replacements or refund about the LED rope lights, please contact our customer service e-mail for a prompt solution, we will get it resolved within 24 hours. Please rest assured that we always get your back whenever you are in need of assistance.
 

Daybetter Bluetooth Led Lights 65.6ft

  • App control led rgb lights
  • App timing and music functions
  • Smart led lights sync with music
  • Can not pair with wifi
  • 65.6 feet length
 

PANGTON VILLA Led Strip Lights 6.56 Feet for 40-60 Inch TV Usb Backlight Kit with Remote Rgb 16 Colors Bias Mood Lamp for Bedroom, Room Hdtv

  • Light up every side of your tv - 78. 7 inch 5050 led light strip for 40-60 inch tv
  • Led tv lights can improve image clarity
  • 24 key remote:16 color, dimmable 4 modes. Control distance 19. 6 Feet-26. 2 Feet
  • Install procedure-double sided adhesive tape Installation, we made the mark on the light strip, just connected it according to the mark
  • Working voltage: The product is powered by dc 5 volt tv usb interface.
 

60ft Daybetter Smart Bluetooth Led Lights,5050 RGB Led Strip Lights Kits with Remote, App Control Timer Schedule Led Music Strip Lights(2 Rolls of 30ft)

  • Led lights with bluetooth: Use your phone to setting it up and turning it on
  • Timer setting: You can use the Led strip lights to set a timer
  • App timing and music functions:Turning on the music mode led strips will change colors sync to music,bringing party effects;The led lights for room 60 feet has color memory function,set the time and let the led strip lights for bedroom automatically turn on and off are your favorite colors
  • Install and use : We use double adhesives, which can solve the problem of falling
  • The strip lights can controll by remote and App on the phone
 

Nexillumi 20 ft LED Lights for Bedroom with Remote Color Changing LED Strip Lights

  • 【Our edges over the other LED light strip brands】①With built-in mic that detects music beats the LED light strip can change colors and brightness automatically along with music, the sensitivity of the mic can be adjusted with "+/-" buttons via the remote ②Comes a timer that turns off the LED lights 15 mins, 30 mins or 1 hr later while you are in bed before sleeping③One push button switch helps to turn on/off the lights and change colors of the lights.
  • 【Upgraded Length from 16.4 ft to 20 ft, from 150 LED beads to 180 LED beads】The extra upgraded length creates more applicable occasions where you can use the LED lights, the versatile LED lights can be used to decorate your bedroom, dorm room, room decor, under the cabinet, screens, beds, shelves, furniture, picture frames, kitchen, ceiling, back of TVs, desk, stairs, home parties for accent effects, illumination, and entertainment.
  • 【Upgraded Brighter SMD 5050 LED chips and durable copper strips】Nexillumi exclusive customized LED chips consume less power while illuminate brighter light with a longer life span of more than 60,000 working hours. The numbers of LED units have also been upgraded from 150 LED lights to 180 to light up more area.
  • 【Upgraded Safest UL listed Power adapter and cords】12V fireproof power adapter that meets the most intricate and rigorous UL standards, the built-in protective circuit will automatically shut down the power once the current is overloaded or short-circuited. ② The cables also passed the UL tests and they have been designed to be more durable.

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.