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Quantum dots are coming - and they are going to revolutionise LED lighting technology. Well, eventually. The LED is the only constantly evolving light source. Incandescents, halogens, and fluorescent bulbs are what they are be it bright or dim, fragile, flickering, and big energy consumers. Over the last century the idea of the LED has grown and so has its functionality as universities and private companies research better, more efficient lighting sources. Currently, the organic LED is the best on the market, but it has the potential to get better. Below, we outline some exciting new LED Light Bulb technology that is sure to disrupt the market place in the near future.

 

What are Quantum Dots?

What are Quantum Dots?

Quantum Dots or QDs are miniscule artificial atom which can be combined into optical chips. Due to its artificial nature, the electrons within a quantum dot can be excited by shining a light on it using a laser. The added effect of this electron excitation is that it leaves a hole for the electron to decay back into - the speed at which this decay happens is crucial. The faster the movement and resultant decay, the faster light is able to leave.

In 1954, Robert Dicke suggested that if the interaction between light and matter could be strengthened, then the efficiency of light emittance would be improved. His idea, which has taken another six decades to prove, is that having multiple atoms sharing an excited state in a quantum superposition would achieve this.

Proving Dicke’s theorum has proven difficult because researchers have previously found that atoms group too close together or spread out too far apart. This inhibits the quantum speed up effect researchers are looking for. However, researchers at the University of Hiroshima and with the Niels Bohr Institute at the University of Copenhagen have made some strides. Soren Stobbe, of the latter institute, says the trick has been to create a quantum dot which acts as if it is 5 dots in one, which then allows a super photon of light to escape when excited.

 

     
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The Si QD Hybrid LED

The Si QD Hybrid LED

QLEDs or QDLEDs are Quantum Dot Light Emitting Diodes are an adaptation of current organic LEDs using nano-scale crystals to improve light generation efficiency. While LEDs are between two and ten times more efficient than other market leaders, they are not so energy efficient. At the moment, organic commercial LED light bulbs use a combination of a blue light and yellow phosphor coating, the latter allowing for a more natural light colour, but causes a 30% drop off in energy efficiency.

This new technology is finding its way into commonly used LED fixtures such as LED Strip Lights more and more each day. Strip lighting is a fantastic way to add colorful light to any room, and with new QLED technology making them more energy efficient than ever, its a no-brainer to start upgrading your lighting today!

Japanese researchers at the University of Hiroshima, including Saito Kenichi, have created the Si QD Hybrid LED which produces 280 times more current power  and 350 times more optical power than the best LEDs produced so far. Furthermore, this optimisation of the LED includes a 40x greater active area than the standard LED light.

The Si QD Hybrid LED is produced by layering a glass substrate with a conductive polymer solution and then a colloidal silicon quantum dot solution on top. It is this silicon layer which gives this type of QD LED it’s name - Si being short for silicon. According to Saito, the process takes place at room temperature and pressure, which may make the LED creation process easier and cheaper in the future.

This, according to Seth Coe-Sullivan of QD Vision, produces a light with a colour temperature of 2,700 kelvins which is analogous with a standard incandescent bulb. This bumps the colour-rendering index, charting how natural a light is with 100% being natural sunlight, for an LED up from 75% to 90%, though the incandescent stays top at 95%. However, as this new hybrid technology continues to become more refined, we will begin to see LED Panels and other LED lighting technologies edge in even more on traditional incandescent lights that are beginning to become a thing of the past.

 

     
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Are QD LEDs Worth It?

A lot of research is going into the development of quantum dot LEDs, but it is worth asking if this is necessary. In simple terms, there are pros and cons of QD LEDs, which we will discuss below, but overall, if researchers can make a more efficient light bulb and light source for TVs, computers and other devices, then it all helps to reduce the amount of electricity we use while improving the quality of artificial light we experience in our homes, places of work, and recreation. Additionally, many end-users look for a bulb that is able to be dimmed on demand, changing the concentration of light in a given room at any time, something that is still be ironed out in the QD LED realm.

Are QD LEDs worth it?

 

Advantages:

* More natural light than previous LEDs.

* Cadmium free - Silicon quantum dots evade the toxicity and environmental dangers of Cadmium Quantum Dot LEDs.

* Higher current density than OLED systems.

* Purer colour with a 30-40% luminance advantage over rivals.

* Overall lower power consumption - half the energy consumption of an OLED light bulb.

 

Disadvantages:

* Not yet usable for light bulb technology.

* Currently expensive to produce though this will decline as demand and manufacturing rates go up and the technology is better developed.

 

Overall, it’s a win for the advantages in the long term. It is also a win for lighting technology designers and eventually interior decorators because the ultra thin, transparent and flexible light format will allow QLEDs to lead innovative designers into making new lighting forms which have not yet been developed due to the limitations of existing technology.

 

The Future is Bright

While the technology has made quantum leaps of late, we have not yet got to the point where QD LED lights will be on the mass market. Saito Kenichi of Hiroshima University, however, believes that a number of breakthroughs will allow a QD-based hybrid LED to enter the market in the future. It is clear that quantum dots have the potential to increase the efficiency of LED lights still further and could provide a more natural source of light - in terms at least of how your skin looks under it. However, the negatives and the current state of the technology suggests it will be a slow, incremental development with quantum dots first taking up home in TV screens and computer/tablet screens before developing enough to go into home or commercial lighting.

 

     
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Resources:

Johnson, Dexter, 2015, Quantum Dots Enable Next Generation of LED Lighting Systems, IEEE Spectrum

Miyokawa, Norifumi, 2015, Next-Generation Illumination Using Silicon Quantum Dot-based White-Blue LED, EurekAlert! Via Hiroshima University

Savage, Neil, 2009, Quantum Dots Enhance LED Lighting, IEEE Spectrum

Stobbe, Soren, 2016, Super Fast Light Source Made from Artificial Atom, EurkeAlert! Via Niels Bohr Institute of the University of Copenhagen