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Metal halide perovskites have emerged as a new class of low-cost solution processable semiconductor materials with applications in a variety of optoelectronic devices, from photovoltaics, to photodetectors, lasers, and light emitting diodes (LEDs). Efficient electrically driven LEDs with green light emission based on lead bromide perovskites, such as MAPbBr3 and CsPbBr3 have been achieved. While electrically driven perovskite LEDs have shown great promise with the device efficiency approaching to those of organic and quantum dot LEDs, a number of challenges, such as long-term stability and color tunability, remain to be addressed before the consideration of commercialization. For full-color display and solid-state lighting applications, highly efficient blue and red LEDs are required in addition to green ones, which however have yet achieved comparable device performance for perovskites-based devices. To implement red perovskite LEDs, two major strategies have been attempted to date, one relying on mixing halide, and the other involving the control of quantum well structures. Mixing halide has been shown to enable precise color tuning of photoluminescence and electroluminescence of perovskite LEDs. However, mixed halide perovskites show relatively low photoluminescence quantum efficiency. More critically, mixed-halide perovskites suffer from low spectral stability due to ion migration and phase separation under illumination and electric field. the change of electroluminescence color during the device operation has been observed in all LEDs based on mixed-halide perovskites. In this invention disclosure, we report bright and efficient red perovskites LEDs with great spectral stability by using quasi-2D halide perovskites/polymer (i.e. PEO, PVK, PIP, etc.) composite thin films as the light-emitting layer. By controlling the molar ratios of large organic salt (i.e. benzyl ammonium iodide, phenethylammonium iodide, butylammonium iodie, etc.) and inorganic salts (Csl and Pbl2), FSU researchers have been able to obtain luminescent quasi-2D perovskite thin films with tunable colors from red peaked at 615 nm to deep red peaked at 676 nm. The perovskites/polymer composite approach enables quasi-2D perovskite/PEO composite thin films to possess much higher photoluminescence quantum efficiencies and smoothness than their neat quasi-2D perovskite counterparts. Advantages include: 1. These quasi-2D halide perovskites/polymer composite thin films have high photoluminescence quantum efficiency and superior thin film morpology. 2. Electrically driven LEDs with tunable emissions based on quasi-2D halide perovskites/polymer composite thin films have been achieved with superior device performance. 3. These devices show exceptional EL spectra stability and device performance stability.
Key Words : Chemical Synthesis, LEDs, Perovskites
Low-cost, nontoxic, highly stable industrial organic pigments are utilized as surface passivation agents for perovskite solar cells (PSCs).
Next-generation thin-film perovskite solar cells have been shown to have major advantages over their silicon-based counterparts. They are low-cost, highly efficient, and are simple to synthesize from earth-abundant materials. However, to become truly competitive with current on-the-market solar cells, PSCs need to overcome the challenge of long-term stability while maintaining their ability to be mass-produced.
Dr. Biwu Ma of Florida State University has developed a method to apply a layer of organic pigments to PSCs as a passivation agent, increasing the useable lifespan of these solar cells. The pigments are well-known, low-cost, and have been shown to improve the efficiency PSCs; in one experiment, the efficiency of a solar cell was increased from 18.9% to 21.1% with the application of the pigment.
The pigments are applied via solution processing of soluble pigment derivatives followed by thermal annealing to convert them into insoluble coating. This enables effective passivation through strong interactions organic pigments and the metal halides of the solar cell. Together with the hydrophobicity of the coating, this enables highly efficient PSCs with remarkable stability.
Since the discovery of carbon nanotubes, materials with tubular structures have attracted scientific interest because of their intriguing physical and/or chemical properties. Besides carbon nanotubes, a number of synthetic tubular structures such as metal oxides, polymers, metal organic frameworks (MOFs) etc. have been developed over the last decades, which show promising applications in various areas, ranging from gas separation and storage, to catalysts, and drug delivery.
Organic-inorganic metal halide hybrids have received research attention for their exceptional optical and/or electronic properties with useful applications in a variety of optoelectronic devices, including photovoltaic cells, light emitting diodes, photodetectors, and lasers. The structural tunability of this class of materials can enable the formation of various types of crystal structures by using appropriate organic and inorganic components, ranging from three- (3D), to two- (2D), one- (1D), and zero-dimensional (0D) structures on the molecular level.
This technology comprises organic metal halide hybrids having a 1D tubular structure, and facile solution processing methods for preparing the metal halide hybrids. For example, the metal halide crystals provided herein may include an array of 1D nanotube structures. In some embodiments, the methods provided herein including simple bottom up solution self-assembly processes.
Light-emitting diodes (LEDs) and organic light-emitting diodes (OLEDs) are used widely in solid state lighting, electronic displays, bio-imaging, and photovoltaic applications. A cheaper, more efficient LED device can impact multiple markets. Some of the primary applications include television displays, mobile device displays, medical applications, solid state lighting, and energy applications.
This LED technology comprises two components—an LED device and the process of manufacturing that device. The LED device comprises earth-abundant materials. The manufacturing process takes place at room temperature using simple starting materials and common organic solvents in a single container. The color of the LEDs can be tuned.
In addition, this technology focuses on using phosphors to get the desired color and intensity of light. Organic/inorganic perovskite materials are abundant, non-toxic, and inexpensive. Thus, by using these materials to create phosphors, the cost of the LED device is reduced significantly. This is especially true as our technology approaches 100% conversion of the base LED energy to the phosphor.
Light-emitting diodes (LEDs) and organic light-emitting diodes (OLEDs) are used widely in solid state lighting, electronic displays, bio-imaging, and photovoltaic (PV) applications. A cheaper, more efficient LED device can impact multiple markets. Some of the primary applications include television displays, mobile device displays, medical applications, solid state lighting, and energy applications.
This LED technology comprises two components—an LED device and the process of manufacturing that device. The LED device comprises earth-abundant materials. The manufacturing process takes place at room temperature using simple starting materials and common organic solvents in a single container. The color of the LEDs can be tuned.
Typically, thin film optoelectronic devices, such as LEDs and PVs, are configured with a layered structure. This includes a photoactive (either light emitting or light harvesting) layer sandwiched between charge transport layers that contact with electrodes. These charge transport layers play a crucial role in efficiency of the entire device.
This technology uses perovskite materials to create cost effective, efficient charge transport layers.
Various types of light emitting materials have been developed, including organic and polymeric emitters, transition metal complexes, rare-earth doped phosphors, nanocrystals, and organic-inorganic hybrid perovskites.
Organic-inorganic metal halide hybrids are a class of crystalline materials that may have unique structures and/or permit the tenability of one or more properties. Metal halide polyhedra can form three- (3D), two- (2D), one- (1D), and zero-dimensional (0D) structures surrounded by organic moieties. The decreased dimensionality of the inorganic structures can lead to the emergence of unique properties. For example, unlike narrow emissions with a small Stokes shift that has been observed in typical 3D metal halide hybrids, broadband photoluminescence with a large Stokes shifts has been realized in corrugated-2D, 1D, and 0D metal halide hybrids, likely due to exciton self-trapping or excited state structural deformation.
This invention comprises a bulk quantum material. In some embodiments, the bulk quantum material includes two or more photo- and/or electro-active species; and a wide band gap organic network comprising a plurality of organic cations; wherein each of the two or more photo- and/or electro-active species are (i) disposed in the wide band gap organic network, and (ii) isolated from each other. In some embodiments, the two or more photo- and/or electro-active species comprise two or more metal halide species.
Dr. Ma has recently developed highly efficient X-ray scintillators with state-of-the-art performance based on organic metal halide hybrids, which could be prepared using a facile solution growth method at room temperature to form inch-sized single crystals. These organic-inorganic hybrid materials with a zero-dimensional
(0D) structure at the molecular level exhibit tunable emissions in the visible spectrum region with high photoluminescence quantum efficiencies (PLQEs) of up to 100%. X-ray imaging tests have showed that scintillators based on powders could provide an excellent visualization tool for X-ray radiography, and
flexible scintillators could be fabricated by blending powders with polymer matrix, such as polydimethylsiloxane (PDMS).
These X-ray scintillators have numerous advantages over currently-used materials: