LEDs are shedding light, so to speak on lighting enthusiasts who felt a little in the dark. Over the last ten years, the lighting industry offered long life, efficiency, and durability features. Research engineers from Princeton illuminated another LED lighting technology path.
The refinement of crystalline light substances, called perovskites, are more efficient and have the potential to be a lower-cost alternative to LED lighting materials currently used. A technique developed by the researchers allows the nanoscale particles to self-assemble. The perovskite-based LEDs are more durable, stable, and efficient than their predecessors.
Nature Photonics reported just this month that the advance has the potential of speeding up perovskite commercial application technologies for computer screens, television, lasers, and lighting. Perovskite performance in solar cells increased in recent years.
The properties give promise for LED lighting. The inability to create perovskite film that is bright and uniform limits the potential. The new technique that allows self-assemblage in the creation of ultra-fine grained films is a fabrication advance that makes perovskite LED lighting a viable alternative to current technology.
Voltage applied across LEDs causes them to emit light. Electrical current forces electrons from negative to positive diodes when the lights are on. The energy released is in the form of light. Strictly controlled current causes the best LED operation. The nanoparticle-based film allows for strictly controlled current.
Researchers are in the process of exploring perovskite as a potentially lower-cost option to materials used in the manufacture of LEDs such as gallium nitride. Positive environmental impact, reduction of energy use, and acceptance of the bulbs are lower-cost benefits.
Lev Perovski, a Russian mineralogist, discovered perovskite in the mid-1800s. Compounds that share the structure of Perovski's discovery are compounds that belong to a class. The crystalline compounds have a distinct combination of diamond and cuboid shapes. Perovskites exhibit intriguing properties.
Depending on the structure, they are either super- or semi-conductive. That property makes them promising for electrical device use. Replacing silicon in solar panels is a potential that is under exploration. Perovskite offers the same efficiency offered by silicon-based LEDs and is less costly to manufacture.
A solution of organic ammonium halide and a metal halide dissolves perovskite precursors to fabricate layers of hybrid organic-inorganic perovskite. The process is simple and relatively cheap with the potential of offering an inexpensive alternative to silicon and other based materials. The semiconductor films, that resulted, emitted vivid color lights.
However, they were unstable and inefficient because the molecular structure of the film crystals was too large. Using an addition ammonium halide in the perovskite solution dramatically constrained the crystal formation in the films. The crystallites that resulted were much smaller than that previsously generated by other methods.
The halide perovskite film was smoother and thinner. Better external quantum efficiency was possible. The efficiency translates to more photons per electrons emitted by LEDs entering a device. The films were more stable than films produced by other methods.
Research brings commercialization of perovskite-based LED lighting closer. The processing scheme is likely to have broad applications to other device platforms and active materials.