1388results about How to "Improve external quantum efficiency" patented technology

The present invention generally relates to organic photosensitive optoelectronic devices. More specifically, it is directed to organic photovoltaic devices, e.g., organic solar cells. Further, it is directed to an optimized organic solar cell comprising multiple stacked subcells in series. High power conversion efficiency are achieved by fabrication of a photovoltaic cell comprising multiple stacked subcells with thickness optimization and employing an electron blocking layer.

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.

A light-emitting element having extremely high efficiency of approximately 25% is provided. The light-emitting element includes a light-emitting layer which contains a phosphorescent guest, an n-type host, and a p-type host, where the light-emitting layer is interposed between an n-type layer including the n-type host and a p-type layer including the p-type host, and where the n-type host and the p-type host are able to form an exciplex in the light-emitting layer. The light-emitting element exhibits an extremely high emission efficiency (power efficiency of 74.3 lm / W, external quantum efficiency of 24.5%, energy efficiency of 19.3%) at a low driving voltage (2.6 V) at which luminance of 1200 cd / m2 is attainable.

A light-emitting element having extremely high efficiency of approximately 25% is provided. The light-emitting element includes a light-emitting layer which contains a phosphorescent guest, an n-type host, and a p-type host, where the light-emitting layer is interposed between an n-type layer including the n-type host and a p-type layer including the p-type host, and where the n-type host and the p-type host are able to form an exciplex in the light-emitting layer. The light-emitting element exhibits an extremely high emission efficiency (power efficiency of 74.3 lm / W, external quantum efficiency of 24.5%, energy efficiency of 19.3%) at a low driving voltage (2.6 V) at which luminance of 1200 cd / m2 is attainable.

A method for designing semiconductor light emitting devices is disclosed wherein the side surfaces (surfaces not parallel to the epitaxial layers) are formed at preferred angles relative to vertical (normal to the plane of the light-emitting active layer) to improve light extraction efficiency and increase total light output efficiency. Device designs are chosen to improve efficiency without resorting to excessive active area-yield loss due to shaping. As such, these designs are suitable for low-cost, high-volume manufacturing of semiconductor light-emitting devices with improved characteristics.

The invention discloses a boron-containing efficient organic electroluminescent compound and application of the compound to an OLED device. The structural formula of the compound is as shown in the general formula (1). Boron atom as the core extends outward three six-membered rings composed of carbon-carbon single bonds, wherein the carbon-carbon single bonds also can be replaced with carbon-oxygen and carbon-nitrogen bonds; a benzene ring is sandwiched between each two six-membered rings; and each phenyl ring is respectively externally connected to hydrogen, aryl group, heteroaryl group, alkyl group, alkyloxy group, or arylamine group. The material has good fluorescence quantum efficiency and electroluminescent efficiency, is easy to form an amorphous film, and has good heat stability. Thus, the material can be used as a luminescent layer material in an organic electroluminescent device.

An organic electroluminescent device having a pair of electrodes and at least one organic layer including a light-emitting layer interposed between the pair of electrodes, in which the organic layer contains at least one compound represented by formula (I):wherein Z1 and Z2 each independently represent a nitrogen-containing heterocycle coordinated with the platinum through a nitrogen atom; Q1 and Q2 each independently represent a group bonded with the platinum through a carbon atom, an oxygen atom, a sulfur atom, a nitrogen atom or a phosphorous atom; Q1 and Q2 each represent a structure different from each other; L1 and L2 each independently represent a single bond or a linking group; and n represents 0 or 1.

The present invention generally relates to organic photosensitive optoelectronic devices. More specifically, it is directed to organic photovoltaic devices, e.g., organic solar cells. More specifically, it is directed to organic photosensitive optoelectronic devices that comprise a cyclometallated organometallic compound as a light absorbing material.

The back surface of a semiconductor crystal substrate 102 which has a thickness of about 150 μm and is made of undoped GaN bulk crystal consists of a polished plane 102a which is flattened through dry-etching and a grinded plane 102b which is formed in a taper shape and is flattened through dry-etching. On about 10 nm in thickness of GaN n-type clad layer (low carrier concentration layer) 104, about 2 nm in thickness of Al0.005In0.045Ga0.95N well layer 51 and about 18 nm in thickness of Al0.12Ga0.88N barrier layer 52 are deposited alternately as an active layer 105 which emits ultraviolet light and has MQW structure comprising 5 layers in total. Before forming a negative electrode (n-electrode c) on the polished plane of the semiconductor substrate a, the polished plane is dry-etched.

A light emitting diode (LED) structure includes a substrate with a surface and cylindrical photonic crystals, a first type doping semiconductor layer, a first electrode, a light emitting layer, a second type doping semiconductor layer and a second electrode. The first type doping semiconductor layer is formed on the substrate to cover the photonic crystals. The light emitting layer, the second type doping semiconductor layer and the second electrode are sequentially formed on a portion of the first type doping semiconductor layer. The first electrode is formed on the other portion of the first type doping semiconductor layer without being covered by the light emitting layer. Because the substrate with photonic crystals can improve the epitaxial quality of the first type doping semiconductor layer and increase the energy of the light forwardly emitting out of the LED, the light emitting efficiency of the LED is effectively enhanced.

A nitride-based light-emitting diode is provided, including a substrate having a light extraction layer grown on the substrate, and a nitride semiconductor epitaxy layer grown on the light extraction layer. The external quantum efficiency is improved by changing the traveling path of the emitted light and by matching the refraction index between the light extraction layer and the substrate. Also, a high power nitride-based light-emitting diode having a sacrificial layer is disclosed. A sacrificial layer is used for growing a light-emitting structure, and a binding layer made of two or more metals or alloys is used to bind the grown light-emitting structure and a substrate with high thermoconductivity. The sacrificial layer is later entirely etched away with a chemical solution used in a chemical etching process, and the nitrogen epitaxy structure is placed on the substrate with high thermoconductivity so that the diode can operate at high electrical current to improve external quantum efficiency.

The present invention relates to a III-nitride semiconductor light-emitting device having high external quantum efficiency, provides a III-nitride compound semiconductor light-emitting device including an active layer generating light by recombination of electrons and holes and containing gallium and nitrogen, an n-type Al(x)ln(y)Ga(1-x-y)N layer epitaxially grown before the active layer is grown, and an n-type electrode electrically contacting with the n-type Al(x)ln(y)Ga(1-x-y)N layer, in which the n-type Al(x)ln(y)Ga(1-x-y)N layer has a surface which is exposed by etching and includes a region for scribing and breaking the device and a region for contact with the n-type electrode, and the surface of the region for scribing and breaking the device is roughened, thereby it is possible to increase external quantum efficiency of the light-emitting device.

A light emitting diode device emitting at a wavelength of 390-415 nm has a bulk gallium and nitrogen containing substrate with an active region. The device has a current density of greater than about 175 Amps / cm2 and an external quantum efficiency with a roll off of less than about 5% absolute efficiency.

Projections / depressions of a two-dimensional periodic structure are formed in a p-GaN layer (4) such that the period of the projections / depressions is 1 to 20 times the wavelength of light radiated from an active layer (3) in a semiconductor. As a result, a diffractive effect achieved by the projections / depressions of the two-dimensional periodic structure change the direction in which the light radiated from the active layer (3) travels. If the projections / depressions are not provided, light at a radiation angle which satisfies conditions for total reflection at the interface between a semiconductor device and an air cannot be extracted to the outside of the semiconductor device so that the light emission efficiency of the device is low. By contrast, the projections / depressions as formed with a period according to the present invention diffract the light at an angle which does not cause total reflection so that the efficiency with which the light is extracted to the outside of the semiconductor device is improved exponentially. This improves the light emission efficiency of the device.

An LED chip (2) emitting blue light is mounted on an insulating substrate (1) at both ends of which electrode films (11, 12) are formed, and a pair of electrodes of the LED chip (2) is electrically connected to the pair of electrode films (11, 12) respectively by connection means (3). On the LED chip (2), there are provided a first resin layer (4) made of resin containing a red color conversion member (4a) for converting blue light into red light and provided so as to coat substantially half of the LED chip (2) and to be in close contact with the LED chip (2), and a second resin layer (5) made of resin containing a green color conversion member (5a) for converting blue light into green light and provided so as to coat similarly the other substantially half of the LED chip (2). As a result, it is possible to attach the resin containing light color conversion members directly to the LED chip in such manner that the red and green light color conversion members are not mixed with each other and obtain a white semiconductor light emitting device having high external quantum efficiency.

Disclosed is an organic electroluminescent element which is characterized in that constituent layers including at least a phosphorescent light-emitting layer are provided between a pair of electrodes, and at least one of the constituent layers contains a compound represented by general formula (1). (In the formula, A1, A2 and A3 each represents a substituent; n1 and n2 each represents an integer of 0-3; X1 and X2 each represents an oxygen atom, a sulfur atom, an alkylene group, an imino group, a carbonyl group, a sulfoxide group or a sulfonyl group, or alternatively X2 represents a bonding hand; and Z1, Z2, Z3 and Z4 each represents an optionally substituted aromatic heterocyclic ring or an aromatic hydrocarbon ring, provided that all of the Z1, Z2, Z3 and Z4 are not aromatic hydrocarbon rings at the same time.)

The present invention discloses a semiconductor light emitting device including an active layer for generating light by recombination of electron and hole between a first semiconductor layer having first conductivity and a second semiconductor layer having second conductivity different from the first conductivity, the second semiconductor layer being disposed on the active layer. The semiconductor light emitting device comprises first array including a trench having a first inclination angle, and second array including a trench having a second inclination angle different from the first inclination angle.