LED - Page 14

Researchers at Duke University have developed a method to create otherwise unattainable (or extremely hard to create) hybrid thin-film materials. The new technique could open the door to new generations of solar cells, light-emitting diodes and photodetectors.

The most common perovskite used in solar energy today, methylammonium lead iodide (MAPbI3), can convert light to energy as well as today's best commercially available solar panels. This can even be done using a fraction of the material - a piece 100 times thinner than a typical silicon-based solar cell. Methylammonium lead iodide is one of the few perovskites that can be created using standard industry production techniques, though it still has issues with scalability and durability. To truly unlock the potential of perovskites, however, new manufacturing methods are needed because the mixture of organic and inorganic molecules in a complex crystalline structure can be difficult to make. Organic elements are particularly delicate, but are critical to the hybrid material's ability to absorb and emit light effectively.

Fuji Pigment recently reported that it is researching and developing a new type of perovskite quantum dots. Fuji stated that the half width of their emission spectra is substantially narrower than that of InP; this property could very beneficial to the application of the dots in display materials, LED, bio-imaging and more.

emission spectra of perovskite quantum dots under 420 nm of irradiation light

The chemical composition of perovskite quantum dots are either CsPbX3 or CH3NH3PbX3 (X= Cl, Br, I). Their quantum efficiency is 50'80 % and their half width is 15'39 nm. Their base solvent is either hexane or toluene. However, finding alternative solvents is a challenge that is now being addressed.

EPFL researchers have designed a new type of inorganic nanocomposite that makes perovskite quantum dots (nanometer-sized semiconducting materials with unique optical properties) exceptionally stable against exposure to air, sunlight, heat, and water.

Quantum dots made from perovskites have already been shown to hold potential for solar panels, LEDs and laser technologies. However, perovskite quantum dots have major issues with stability when exposed to air, heat, light, and water. The EPFL team has now succeeded in building perovskite quantum dot films with a technique that helps them overcome these weaknesses.

Researchers at Los Alamos National Laboratory and their partners are creating innovative 2D layered hybrid perovskites that they say can allow greater freedom in designing and fabricating efficient optoelectronic devices. Industrial and consumer applications could include low cost solar cells, LEDs, laser diodes, detectors, and other nano-optoelectronic devices.

They explain that these materials are layered compounds, or a stack of 2D layers of perovskites with nanometer thickness (like a stack of sheets), and the 2D perovskite layers are separated by thin organic layers. "This work could overturn conventional wisdom on the limitations of device designs based on layered perovskites", the team says.

A team of researchers from the University of Macau (UM), Nanjing Tech University, and Nanyang Technological University, Singapore, has announced a significant breakthrough, laying a theoretical foundation for high-efficiency and low-cost perovskite light emitting diode (LED). The research is said to be able to significantly improve the luminous efficiency of perovskite LED and have the potential to advance low-cost, high-efficiency LED displays and LED light sources.

The team discovered that the slow bimolecular recombination that drives 3D lead-halide perovskites' excellent photovoltaic performance is conversely a fundamental limitation for electroluminescence. The team found that the slow bimolecular recombination limitation can be overcome so that high-efficiency electroluminescence can be achieved.

Researchers at Princeton University have developed a technique in which nanoscale perovskite particles self-assemble to produce more efficient, stable and durable perovskite-based LEDs. This advance could speed the use of perovskite technologies in commercial applications such as lighting, lasers and television and computer screens.

The team explains that this technique allows nanoparticles of perovskite to self-assemble to create ultra-fine grained films, an advance in fabrication that could make perovskite LEDs a viable possibility.

EPFL scientists have developed a new perovskite material whose magnetic order can be rapidly changed without disrupting it due to heating. This novel material may potentially be used to build next-generation hard drives.

The EPFL team synthesized a ferromagnetic photovoltaic material. This material is a modified version of perovskite, that exhibits unique properties that make it particularly interesting as a material to build next-generation digital storage systems. The researchers explain that they have basically created the first magnetic photoconductor; This new crystal structure combines the advantages of both ferromagnets, whose magnetic moments are aligned in a well-defined order, and photoconductors, where light illumination generates high density free conduction electrons.

Perovskites that are direct-bandgap semiconductors could be real alternatives to current materials used in LEDs - for applications such as displays and lighting. Perovskite could lead the way towards easy-to-produce, affordable and efficient LED devices. Read out new article Perovskite for LEDs to find out more!

A team of researchers from the King Abdullah University of Science and Technology (KAUST) of the Kingdom of Saudi Arabia has reported a perovskite-based phosphor-based white light converter with a modulation bandwidth around 40 times higher than common LED phosphors. This result could put an end to today's VLC bottleneck when using white LEDs.

By mixing solution-processed CsPbBr3 perovskite nanocrystals (NCs) with a conventional red phosphor, they obtained what they describe as a perovskite-based phosphor white light converter with a modulation bandwidth of 491MHz, which could support high data rate up to 2 Gbit/s, much faster than Wi-Fi. In addition to exhibiting a shorter excited lifetime, the red phosphor and perovskite composite material yields a white light with a high colour rendering index of 89 and a correlated colour temperature of 3236 K, which makes the white LED suitable for comfort lighting applications.

Researchers at Nanyang Technological University in Singapore have fabricated high-performance green light-emitting diodes based on colloidal organometal perovskite nanoparticles. The devices have a maximum luminous efficiency of 11.49 cd/A, a power efficiency of 7.84 lm/W and an external quantum efficiency of 3.8%. This value is said to be about 3.5 times higher than that of the best colloidal perovskite quantum-dot-based LEDs previously made.

The team developed a simple way to make a series of colloidal (CH3NH3)PbX3 nanoparticles with an amorphous structure that can be tuned to emit light in the ultraviolet to near-infrared range. They studied the photoluminescence properties of the nanoparticles and found that the PLQE of the perovskite NP film is much higher than that of the bulk film. They then made the highly efficient green LED.