21 June 2024
Green gap cubic nitride closes efficiency gap

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Green gap cubic nitride closes with 32% internal quantum efficiency. Color mixing is the process of combining two or more colors: red and green make yellow, blue and red make purple, red and green and blue make white. This process of mixing colors is the basis for the future of solid-state lighting. While currently white light is achieved by phosphor down-conversion, LED color mixing actually has a higher theoretical maximum efficiency, which is needed in order to achieve the 2035 DOE energy efficiency goals.

Green Gap Cubic Nitride: The Key to Efficient Color Mixing in Solid-State Lighting



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Solid-state lighting (SSL) is the future of lighting technology, offering significant energy savings and longer lifespans compared to traditional incandescent and fluorescent bulbs. At the heart of SSL are light-emitting diodes (LEDs), which convert electrical energy directly into light.

One of the challenges in SSL is achieving white light, which is a combination of different colors. Currently, white light is typically produced using a blue LED coated with a phosphor material that converts some of the blue light into yellow, green, and red light. This process, known as phosphor down-conversion, is inefficient and limits the overall efficiency of SSL systems.

Green Gap Cubic Nitride: A Hurdle in Color Mixing

A major obstacle in achieving efficient color mixing with LEDs is the so-called “green gap.” This refers to the lack of suitable green LEDs that can produce high-quality green light with high efficiency. Current green LEDs made from hexagonal III-nitride materials suffer from low efficiency and efficiency droop at high current densities.

Cubic III-Nitride: A Potential Solution

Researchers have been exploring cubic III-nitride materials as a promising alternative for green LEDs. Cubic III-nitrides have different crystal structures compared to hexagonal III-nitrides, and they exhibit unique properties that could potentially overcome the challenges faced by hexagonal III-nitrides.

Recent Breakthrough: High-Efficiency Green Emission

In a recent study, researchers at the University of Illinois Urbana-Champaign have made a significant breakthrough in the development of cubic III-nitride LEDs. They have demonstrated a green-emitting cubic III-nitride active layer with an impressive internal quantum efficiency (IQE) of 32%. This is more than six times higher than the efficiency reported for conventional cubic active layers.

Key to Success: Aspect Ratio Phase Trapping

The researchers achieved this high efficiency by using a novel technique called aspect ratio phase trapping. This technique involves growing the cubic III-nitride material in a way that traps defects and undesirable phases within the material, leaving a high-quality, pure cubic-phase material on the surface.

Implications for SSL

The development of high-efficiency cubic III-nitride green LEDs could have significant implications for SSL. By filling the green gap, it becomes possible to achieve more efficient color mixing with LEDs, leading to higher overall efficiency in SSL systems. This could potentially revolutionize the lighting industry and contribute to significant energy savings.

Wrapping Up

The recent breakthrough in cubic III-nitride green LEDs represents a major step forward in the quest for more efficient SSL systems. With further research and development, cubic III-nitride LEDs could pave the way for a new generation of lighting technology that is both energy-efficient and cost-effective..

FAQ’s

What is solid-state lighting (SSL)?

Solid-state lighting (SSL) is a lighting technology that uses light-emitting diodes (LEDs) to convert electrical energy directly into light. LEDs offer significant energy savings and longer lifespans compared to traditional incandescent and fluorescent bulbs.

What is the challenge in achieving white light with LEDs?

Achieving white light with LEDs is challenging because white light is a combination of different colors. Currently, white light is typically produced using a blue LED coated with a phosphor material that converts some of the blue light into yellow, green, and red light. This process is inefficient and limits the overall efficiency of SSL systems.

What is the green gap?

The green gap refers to the lack of suitable green LEDs that can produce high-quality green light with high efficiency. Current green LEDs made from hexagonal III-nitride materials suffer from low efficiency and efficiency droop at high current densities.

How can cubic III-nitride materials help overcome the green gap?

Cubic III-nitride materials have different crystal structures compared to hexagonal III-nitrides, and they exhibit unique properties that could potentially overcome the challenges faced by hexagonal III-nitrides. Researchers believe that cubic III-nitride LEDs could potentially achieve higher efficiency and fill the green gap.

What is the significance of the recent breakthrough in cubic III-nitride green LEDs?

The recent breakthrough in cubic III-nitride green LEDs represents a major step forward in the quest for more efficient SSL systems. Researchers at the University of Illinois Urbana-Champaign have demonstrated a green-emitting cubic III-nitride active layer with an impressive internal quantum efficiency (IQE) of 32%. This high efficiency could lead to more efficient color mixing with LEDs and higher overall efficiency in SSL systems.

Links to additional Resources:

1. www.nature.com/articles/s41467-022-33905-7 2. www.osapublishing.org/oe/fulltext.cfm?uri=oe-29-24-39675&id=453618 3. www.sciencedirect.com/science/article/pii/S0925400522008556

Related Wikipedia Articles

Topics: solid-state lighting, light-emitting diodes, III-nitride materials

Solid-state lighting
Solid-state lighting (SSL) is a type of lighting that uses semiconductor light-emitting diodes (LEDs), organic light-emitting diodes (OLED), or polymer light-emitting diodes (PLED) as sources of illumination rather than electrical filaments, plasma (used in arc lamps such as fluorescent lamps), or gas. Solid state electroluminescence is used in SSL, as...
Read more: Solid-state lighting

Light-emitting diode
A light-emitting diode (LED) is a semiconductor device that emits light when current flows through it. Electrons in the semiconductor recombine with electron holes, releasing energy in the form of photons. The color of the light (corresponding to the energy of the photons) is determined by the energy required for...
Read more: Light-emitting diode

Aluminium nitride
Aluminium nitride (AlN) is a solid nitride of aluminium. It has a high thermal conductivity of up to 321 W/(m·K) and is an electrical insulator. Its wurtzite phase (w-AlN) has a band gap of ~6 eV at room temperature and has a potential application in optoelectronics operating at deep ultraviolet...
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