4397 results about "Quantum efficiency" patented technology

Provided are red phosphorescent compounds represented by Formula 1:

Organic electroluminescent devices using the red phosphorescent compounds are further provided. The organic electroluminescent devices exhibit good red color purity, high quantum efficiency, high power efficiency, high luminance, and long lifetime.

The present invention describes a method and apparatus for measuring the voltage and current characteristics of the OLED pixel as it ages and correlating the measured data to the decrease in quantum efficiency and changes in OLED impedance over the life of the OLED, so that corrections can be made to the image drive system to prevent image sticking and color point drift. The method and apparatus of the present invention do not require any additional circuitry or changes in the display design. The circuitry of the present invention is implemented in the display driver integrated circuit (IC) chips. The basis of the invention is the luminance-current-voltage (LIV) curves which characterize the OLED materials over their life time. A series of these curves are stored in memory representing a OLED material at various ages. The apparatus of the present invention is used to measure driver voltages and currents for a pixel having an OLED, which measurements are then used to extract the voltage current curve for the OLED at any point in time. The extracted curve is compared to the aging curves stored in memory to determine the aging curve that best describes the measured present voltage current characteristic of the pixel. That aging curve is used to drive the pixel.

Matrixes doped with semiconductor nanocrystals are provided. In certain embodiments, the semiconductor nanocrystals have a size and composition such that they absorb or emit light at particular wavelengths. The nanocrystals can comprise ligands that allow for mixing with various matrix materials, including polymers, such that a minimal portion of light is scattered by the matrixes. The matrixes of the present invention can also be utilized in refractive index matching applications. In other embodiments, semiconductor nanocrystals are embedded within matrixes to form a nanocrystal density gradient, thereby creating an effective refractive index gradient. The matrixes of the present invention can also be used as filters and antireflective coatings on optical devices and as down-converting layers. Processes for producing matrixes comprising semiconductor nanocrystals are also provided. Nanostructures having high quantum efficiency, small size, and/or a narrow size distribution are also described, as are methods of producing indium phosphide nanostructures and core-shell nanostructures with Group II-VI shells.

A semiconductor sensor, solar cell or emitter, or a precursor therefor, has a substrate and one or more textured semiconductor layers deposited onto the substrate. The textured layers enhance light extraction or absorption. Texturing in the region of multiple quantum wells greatly enhances internal quantum efficiency if the semiconductor is polar and the quantum wells are grown along the polar direction. Electroluminescence of LEDs of the invention is dichromatic, and results in variable color LEDs, including white LEDs, without the use of phosphor.

A high external quantum efficiency is stably secured in a semiconductor light emitting device. At least one recess and/or protruding portion is created on the surface portion of a substrate for scattering or diffracting light generated in a light emitting region. The recess and/or protruding portion has a shape that prevents crystal defects from occurring in semiconductor layers.

Matrixes doped with semiconductor nanocrystals are provided. In certain embodiments, the semiconductor nanocrystals have a size and composition such that they absorb or emit light at particular wavelengths. The nanocrystals can comprise ligands that allow for mixing with various matrix materials, including polymers, such that a minimal portion of light is scattered by the matrixes. The matrixes are optionally formed from the ligands. The matrixes of the present invention can also be utilized in refractive index matching applications. In other embodiments, semiconductor nanocrystals are embedded within matrixes to form a nanocrystal density gradient, thereby creating an effective refractive index gradient. The matrixes of the present invention can also be used as filters and antireflective coatings on optical devices and as down-converting layers. Processes for producing matrixes comprising semiconductor nanocrystals are also provided. Nanostructures having high quantum efficiency, small size, and/or a narrow size distribution are also described, as are methods of producing indium phosphide nanostructures and core-shell nanostructures with Group II-VI shells.

A high efficiency and high brightness multi-active layer tunneling regenerated white color semiconductor light emitting diode having a p type electrode 1, a monolithic red light cell 14, a tunnel junction 9, a monolithic green light 15 and blue light cell 16 (or a monolithic cyan light cell 19), wherein each of said cells are electrically connected by tunnel junctions 9, and the red cell physically connected with blue and green cell (or cyan cell) by wafer bonding layer 8. The lights from each cell synthesize white color light. The white light emitting diode only has one time optical-electrical conversion, so the quantum efficiency is high. Moreover, the white LED totally made from semiconductor materials, the lifetime of the white LED lamp is not limited by the relatively short lifetime of fluorescent material.

The invention provides a quantum dot luminescent device. The quantum dot luminescent device comprises an anode, a hole transport layer, a quantum dot luminescent layer, an electronic transfer layer and a cathode which are arranged sequentially and adjacently. The quantum dot luminescent device further comprises an electronic barrier layer. The electronic barrier layer is arranged in the electronic transfer layer or between the quantum dot luminescent layer and the electronic transfer layer. Due to the arrangement of the electronic barrier layer, balance injection of charge carriers is ensured, automatic charge transfer between the electronic transfer layer and the quantum dot luminescent layer is isolated, electric neutrality of a quantum dot is ensured, then the quantum dot luminescent device can keep deserved luminous efficiency, the external quantum efficiency of the quantum dot luminescent device is improved, and meanwhile the service life of the quantum dot luminescent device is largely prolonged.

A pixel cell array architecture having a multiple pixel cells with shared pixel cell components. The individual pixel cell architecture increases the fill factor and the quantum efficiency for the pixel cell. The common pixel cell components may be shared by a number of pixels in the array, and may include several components that are associated with the readout of a signal from the pixel cell. Other examples of the pixel array architecture having improved fill factor for pixels in the array include an angled transfer gate and an efficiently located, shared capacitor.

Described herein are techniques for authenticating and identifying objects using markings formed with correlated random patterns. In one embodiment, an object to be authenticated includes a substrate and a marking adjacent to the substrate. The marking includes a luminescent material distributed in accordance with a correlated random pattern, and the luminescent material exhibits photoluminescence having a quantum efficiency of at least 10 percent.

To provide a back-illuminated solid-state imaging device able to suppress a crystal defect caused by a metal contamination in a process and to suppress a dark current to improve quantum efficiency, a camera including the same and a method of producing the same, having the steps of forming a structure including a substrate, a first conductive type epitaxial layer and a first conductive type impurity layer, the first conductive type epitaxial layer being formed on the substrate to have a first impurity concentration, and the first conductive type impurity layer being formed in a boundary region to have a second impurity concentration higher than the first impurity concentration of the epitaxial layer; forming a second conductive type region storing a charge generated by a photoelectric conversion in the epitaxial layer; forming an interconnection layer on the epitaxial layer; and removing the substrate.

The present invention relates to a fabrication method of nitride-based semiconductors and a nitride-based semiconductor fabricated thereby. In the fabrication method of the invention, a self-organizing metal layer is formed on a sapphire substrate. The sapphire substrate having the self-organizing metal layer is heated so that self-organizing metal coalesces into nanoscale clusters to irregularly expose an upper surface of the sapphire substrate. Exposed portions of the sapphire substrate is plasma etched using the self-organized metal clusters as a mask to form a nanoscale uneven structure on the sapphire substrate. A resultant structure is wet etched to remove the self-organized metal clusters. The nanoscale uneven structure formed on the sapphire substrate decreases the stress and resultant dislocation between the sapphire substrate and a nitride-based semiconductor layer as well as increases the quantum efficiency between the same.

This invention relates to a photovoltaic device including an electrode such as a front electrode/contact. In certain example embodiments, the front electrode of the photovoltaic device includes a multi-layered transparent conductive coating which is sputter-deposited on a textured surface of a patterned glass substrate. In certain example embodiments, a maximum transmission area of the substantially transparent conductive front electrode is located under a peak area of a quantum efficiency (QE) and/or QEx (photon flux of solar radiation) curve of the photovoltaic device and a light source spectrum used to power the photovoltaic device. In certain example embodiments, the front electrode includes a transparent conductive layer of or including one or more of (i) titanium zinc oxide doped with aluminum and/or niobium, and/or (ii) titanium niobium oxide.

A source and/or method of generating quantum-correlated and/or entangled photon pairs using parametric fluorescence in a fiber Sagnac loop. The photon pairs are generated in the 1550 nm fiber-optic communication band and detected by a detection system including InGaAs/InP avalanche photodiodes operating in a gated Geiger mode. A generation rate>10³ pairs/s is observed, a rate limited only by available detection electronics. The nonclassical nature of the photon correlations in the pairs is demonstrated. This source, given its spectral properties and robustness, is well suited for use in fiber-optic quantum communication and cryptography networks. The detection system also provides high rate of photon counting with negligible after pulsing and associated high quantum efficiency and also low dark count rate.

The invention discloses a carbon nano-dot, and a preparation method and an application thereof, and solves a problem that the application of present nano-dots is restricted because of high preparation cost and easy fluorescent quenching appearance of an aggregate state. According to the invention, the carbon nano-dot having a high fluorescence quantum efficiency is prepared through adopting a polycarboxyl or polyhydroxy contained organic compound, or an amino acid as a raw material, and urea as a surface passivation modification agent, and through a microwave process, and a carbon nano-dot fluorescent ink is prepared through using the carbon nano-dot. The preparation method disclosed in the invention has the advantages of simplicity, low cost and convenient large-scale production; the fluorescent quenching of the prepared carbon nano-dot on the surface of a biological product does not appear, and the highest fluorescence quantum efficiency is 42%; and the prepared carbon nano-dot fluorescent ink is nontoxic, does not generate a precipitate after long-time dispose, and can be applied to the biological imaging field, the biological product identification field, the information storage field, the information encryption field, the false proof field, the illumination display field, the photovoltaic device field and the like.

An imager pixel array capable of separating and detecting the spectral components of an incident light without the use of a color filter array. The imager pixel array employs a grating layer which allows one or more spectral components of incident light to be transmitted therethrough, but diffracts other spectral components of the incident light. Both the transmitted and diffracted spectral components can be sensed by photosensors in the imager pixel array and used in subsequent data processing, thereby improving the quantum efficiency of the imager device. The grating layer can be formed of first and second materials each having a refractive index which are substantially the same at a predetermined wavelength.

A nitride semiconductor light-emitting element suppresses leakage currents and non-radiative recombination centers by providing, as an underlying layer of the active layer, a pit formation layer that reliably generates pits, while maintaining a good film quality, so that the internal quantum efficiency is improved, and the light-emitting characteristics are also improved. A nitride semiconductor lamination portion including at least an active layer for forming a light-emitting portion is present on a substrate, and a pit formation layer is formed as a superlattice layer of nitride semiconductor on the side of the substrate of the active layer. The pit formation layer generates pits in the end portions of threading dislocations that are generated in the nitride semiconductor layer on the side of the substrate.

The present invention provides a fluorescent substance excellent both in quantum efficiency and in temperature characteristics, and also provides a light-emitting device utilizing the fluorescent substance. This fluorescent substance contains an inorganic compound comprising a metal element M, a trivalent element M¹ other than the metal element M, a tetravalent element M² other than the metal element M, and either or both of O and N. In the inorganic compound, the metal element M is partly replaced with a luminescence center element R. The crystal structure of the fluorescent substance is basically the same as Sr₃Al₃Si₁₃O₂N₂₁, but the chemical bond lengths of M¹-N and M²-N are within the range of ±15% based on those of Al—N and Si—N calculated from the lattice constants and atomic coordinates of Sr₃Al₃Si₁₃O₂N₂₁, respectively. The fluorescent substance emits luminescence having a peak in the range of 490 to 580 nm when excited with light of 250 to 500 nm.

Photovoltaic devices or solar cells are provided having one or more photoactive layers where at least one of the photoactive layers comprises a sublayer made of photoactive nanoparticles that differ in size, composition or both.