LED stands for Light Emitting Diode, first developed in 1962, an LED generates light in a quantum well by the movement of electrons through a semiconductor material. Even though LEDs have long been in use in the electronics industry as indicator lights, only in the last decade have they been utilized for general illumination purposes due to a breakthrough by Professor Nakashima in Japan first to help commercialize blue emitting laser diodes based on a quantum well using Gallium-Nitride.
Solid-State lighting (SSL) is most commonly seen in the form of Light Emitting Diodes (LEDs), when applied efficiently can revolutionize the efficiency, appearance, and quality of lighting as we know it.
The term "solid state" refers commonly to light emitted by solid-state electroluminescence, as opposed to incandescent bulbs (which use thermal radiation) or fluorescent tubes that create high intensity UV in a mercury vapor atmosphere. Compared to incandescent lighting, SSL creates visible light more efficiently with reduced heat generation. ActiveLED SSL is environmentally safe as it does not contain mercury.
ActiveLED uses the most efficient "white" LEDs that convert blue light from a solid-state device to white light spectrum using photoluminescence, the same principle used in conventional fluorescent tubes or Compact Fluorescent (CFL) bulbs.
LED lighting can be more efficient, durable, versatile and longer lasting than incandescent Metal Halide (MH), High Pressure Sodium (HPS) and fluorescents lighting. LEDs also emit light in a specific direction, whereas an incandescent or fluorescent bulb emits light and heat in all directions. ActiveLED lighting uses both light and energy more efficiently and ActiveLED outperforms its' LED peers by 30-50% as not all LEDs are created equal.
For example, an incandescent or compact fluorescent (CFL) bulb inside of a recessed can will waste about half of the light that it produces, while a recessed down light with LEDs only produces light where it’s needed, in the room below.
Incandescent bulbs create light by passing electricity through a metal filament until it becomes so hot that it glows to create light. Incandescent bulbs therefore release more than 90% of their energy as heat.
In a compact fluorescent lamp (CFL), an electric current is driven through a tube containing mercury vapor and other noble gases. Gas-discharge exitation produces ultraviolet light that gets transformed into visible light by the fluorescent coating on the inside of the tube. A CFL therefore releases about 80% of its energy as heat.
There are two ways of producing high intensity white-light using LEDs. One is to use individual LEDs that emit three primary colors (red, green, and blue) and then mix all the colors to form white light. The other is to use a phosphor material to convert monochromatic light from a blue or UV LED to broad-spectrum white light, much in the same way a fluorescent light bulb works.
White LEDs can achieve almost any color temperature of white within the visible spectrum and the most desirable color temperatures are 2700K, 3000K, 3500K and 5000K. If you want more background information see article How to Choose the Right Color Temperature for Office or Classroom.