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NOVELED Company Profile
Novel Lighting Solutions for Sustainable Earth |
Motivation
The total annual energy consumption in the United States for lighting is approximately 800 Terawatt-hours and costs $80 billion to the public. The energy consumed for lighting throughout the world entails to greenhouse gas emission equivalent to 70% of the emissions from all the cars in the world. We propose an affordable, durable and environmentally benign lighting solution based on our novel green light emitting diodes, which can perform at higher energy conversion efficiency to drastically reduce the energy consumption and sustain the lowering of greenhouse gas emissions. Competing Technologies
The current lighting technologies include light bulbs and fluorescent tubes that are limited to an efficiency of 5% and 25%, and to a lifetime of 1,000hr and 10,000hr, respectively. However, light emitting diodes (LEDs) can offer an efficiency of more than 50% with 100,000hr lifetime. The performance of current green LEDs is quite low to be used with the other readily available LEDs such as the efficient blue LEDs, which enabled the blue-ray technology, to generate white LEDs based on color mixing. Because the human eye is most sensitive to green (λ~555 nm) and green light strongly affects the human perception to the quality of white light, lack of efficient green LEDs prevents the large scale replacement of all current lighting solutions with efficient LED products. Our novel ZnO-(In)GaN green LEDs, which can perform at high efficiency, can enable energy-efficient lighting solutions for everyday life. Innovative Approach : NOVELED
LEDs based on In(x)Ga(1-x)N active layer are the most promising candidates for fulfilling the green gap. Conventionally, a GaN layer is grown on top of an InGaN multi-quantum-well (MQW) active layer to complete the LED. This GaN layer is grown at significantly higher temperature Ts than the InGaN MQW active layer in order to obtain high structural quality. This leads, however, to indium leaking out of the active layers, which reduces the LED efficiency and spectral quality. ZnO, being a wide bandgap material that has the same crystal structure as GaN, makes a good candidate for integration in InGaN devices. Through use of pulsed laser deposition for ZnO growth, the ultimate growth step could be performed at significantly lower Ts than is typically required for GaN growth. In our NOVELED technology, ZnO layer was substituted for GaN layer in an (In)GaN-based visible LEDs. The top layer was thus ZnO rather than GaN that prevents thermal-induced indium diffusion enabling ZnO-InGaN-based LEDs with superior performance, especially in green regime. Potential Markets and Market Share
The current market of LED is on the order of 5 billion in 2008, with many applications ranging from signage to cell phones/TVs due to its 10 times longer life time than any lighting source.
With the accelerated research effort, we expect to improve efficiency above fluorescent light sources, that will lead a larger market share.
When we look into the market share of the white LEDs particularly, that are composed of green LEDs, it is expected to increase every year, and promises to many other applications. Our novel technological approach to visible LEDs promises high efficiency-LEDs with superior spectral quality: NOVELEDs.
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