white light

LEDs have become the standard source of energy-efficient lighting. They make use of semiconductors to turn electricity into light. Depending upon the materials used to make them, LEDs produce different colors. In the early 1990s, the first blue LEDs were discovered, ultimately earning the Nobel Prize in physics, and enabling LEDs to produce white light, which is essential for general lighting applications.

Blue LEDs have shortcomings. Some have issues with stability, scalability, cost, efficiency, complexity in manufacturing, or have environmental concerns because of the use of toxic components.

Researchers at Rutgers University in collaboration with scientists at several other institutions have found a way to make blue LEDs more efficient and sustainable. These LEDs use a new type of hybrid material that is a combination of copper iodide with organic molecules. The impressive performance of these LEDs was achieved through an innovative technique called dual interfacial hydrogen-bond passivation. This new manufacturing technique boosts the performance of LEDs by a factor of four.

The material has several advantages. It has a very high photoluminescence quantum yield, which means that it converts nearly all the photoenergy it receives into blue light. The LEDs last longer than many others and they work well in larger-scale applications, maintaining high efficiency. The materials are eco-friendly and cost-effective.

According to the researchers, this new approach could be a versatile strategy for generating high-performance LEDs that can pave the way for better, brighter, and longer-lasting LEDs.

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Scientists Develop Deep-Blue LEDs Expected to Greatly Enhance General Lighting

Photo, posted February 1, 2021, courtesy of Ivan Radic via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

A recent study at North Carolina State University has shown that it can be feasible to use see-through solar panels in greenhouses to generate electricity. The idea is to use semi-transparent solar panels on greenhouses that allow some of the light to get in for the plants to grow while making the greenhouses energy neutral or even allowing them to generate more power than they use.

The question is how the semi-transparent solar panels might affect greenhouse crops. To investigate this issue, researchers grew crops of red leaf lettuce from seed to full maturity under a standard set of growing conditions – temperature, water, fertilizer, and CO2 concentration – but varied the light they get.

A control group was exposed to the full spectrum of white light while three experimental groups were exposed to light through different types of filters that absorbed the particular wavelengths of light that would be absorbed by different types of semitransparent solar cells.

The researchers paid close attention to characteristics of the lettuce that are important to growers, grocers, and consumers: general appearance, leaf number, leaf size, and weight. The results were that the lettuce produced using all three kinds of filtered light was essentially identical to that produced in the control group. Further research is underway looking at how harvesting various wavelengths of light affects biological processes for lettuces, tomatoes, and other crops.

Getting growers to use solar-powered greenhouses would be very difficult if doing so would result in a loss of productivity. But given these experimental results, it appears as though the decision will boil down to a simple economic argument about whether the investment in new greenhouse technology would be offset by energy production and its resultant savings.

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Study Finds Plants Would Grow Well in Solar Cell Greenhouses

Photo, posted April 8, 2008, courtesy of Brian Boucheron via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Better blue LEDs

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Solar Cell Greenhouses | Earth Wise

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