A semiconductor light emitting element is provided. The semiconductor light emitting element has a semiconductor stack, an n-side conductor layer, a p-side conductor layer, a dielectric multilayered film, an n-side reflective layer and a p-side reflective layer, disposed in that order. The n-side and p-side reflective layers contain Ag as a major component and contain particles of at least one selected from an oxide, a nitride, and a carbide.

A method of producing semiconductor nanoparticles is provided. The method includes heating primary semiconductor nanoparticles and a salt of an element M.sup.1 in a solvent at a temperature set in a range of 100 C. to 300 C. The primary semiconductor nanoparticles contain the element M.sup.1, an element M.sup.2, optionally an element M.sup.3, and an element Z, and have an average particle size of 50 nm or less. The element M.sup.1 is at least one element selected from the group consisting of Ag, Cu, and Au. The element M.sup.2 is at least one element selected from the group consisting of Al, Ga, In, and Tl. The element M.sup.3 is at least one element selected from the group consisting of Zn and Cd. The element Z is at least one element selected from the group consisting of S, Se, and Te.

A method for manufacturing a quantum dot and a quantum dot are provided. The method includes adding a core semiconductor precursor solution into a seed composition solution. The seed composition solution includes a seed composition, and the seed composition is a dendrimer-metal nanoparticle composite. The core semiconductor precursor solution includes a first semiconductor ion and a second semiconductor ion. The method also includes carrying out a first synthesis reaction to form a core semiconductor material wrapping the seed composition. The core semiconductor material is formed by combining the first semiconductor ion with the second semiconductor ion.

Provided is a ternary or quaternary semiconductor nanoparticle that enables the band-edge emission and a less toxic composition. A semiconductor nanoparticle is provided that contains Ag, In, and S and has an average particle size of 50 nm or less, wherein the ratio of the number of atoms of Ag to the total number of atoms of Ag and In is 0.320 or more and 0.385 or less, the ratio of the number of atoms of S to the total number of atoms of Ag and In is 1.20 or more and 1.45 or less. The semiconductor nanoparticle is adapted to emit photoluminescence having a photoluminescence lifetime of 200 ns or less upon being irradiated with light having a wavelength in a range of 350 nm to 500 nm.

A semiconductor light emitting element is provided. The semiconductor light emitting element has a semiconductor stack, an n-side conductor layer, a p-side conductor layer, a dielectric multilayered film, an n-side reflective layer and a p-side reflective layer, disposed in that order. The n-side and p-side reflective layers contain Ag as a major component and contain particles of at least one selected from an oxide, a nitride, and a carbide.

A semiconductor nanoparticle includes a core and a shell covering a surface of the core. The shell has a larger bandgap energy than the core and is in heterojunction with the core. The semiconductor nanoparticle emits light when irradiated with light. The core is made of a semiconductor that contains M.sup.1, M.sup.2, and Z. M.sup.1 is at least one element selected from the group consisting of Ag, Cu, and Au. M.sup.2 is at least one element selected from the group consisting of Al, Ga, In and Tl. Z is at least one element selected from the group consisting of S, Se, and Te. The shell is made of a semiconductor that consists essentially of a Group 13 element and a Group 16 element.

A semiconductor nanoparticle includes a core and a shell covering a surface of the core. The shell has a larger bandgap energy than the core and is in heterojunction with the core. The semiconductor nanoparticle emits light when irradiated with light. The core is made of a semiconductor that contains M.sup.1, M.sup.2, and Z. M.sup.1 is at least one element selected from the group consisting of Ag, Cu, and Au. M.sup.2 is at least one element selected from the group consisting of Al, Ga, In and Tl. Z is at least one element selected from the group consisting of S, Se, and Te. The shell is made of a semiconductor that consists essentially of a Group 13 element and a Group 16 element.

Provided is a ternary or quaternary semiconductor nanoparticle that enables the band-edge emission and a less toxic composition. A semiconductor nanoparticle is provided that contains Ag, In, and S and has an average particle size of 50 nm or less, wherein the ratio of the number of atoms of Ag to the total number of atoms of Ag and In is 0.320 or more and 0.385 or less, the ratio of the number of atoms of S to the total number of atoms of Ag and In is 1.20 or more and 1.45 or less. The semiconductor nanoparticle is adapted to emit photoluminescence having a photoluminescence lifetime of 200 ns or less upon being irradiated with light having a wavelength in a range of 350 nm to 500 nm.

A device and associated method are provided for a light emitting diode device (LED) with suppressed quantum dot (QD) photobrightening. The QD surfaces, with a maximum cross-sectional dimension of 10 nanometers, are treated with a solution including a multi-valent cation salt. In response to heating the solution, multi-valent cations become attached to the surface of the QD nanocrystals, forming treated QDs that are deposited overlying a top surface of an LED. The LED device emits a non-varying intensity of first wavelength light in the visible spectrum from the treated QDs, when subjected to a continuous exposure of a second wavelength of LED light having an intensity of greater than 50 watts per square centimeter. For example, blue, green, or red color light may be emitted when exposed to LED light in the ultraviolet (UV) spectrum, or a green or red color light when exposed to a blue color LED light.

A tunable photocathode for use in vacuum electronic devices includes a nanostructured photoemission layer including quantum confined nanostructures, such as quantum dots. The quantum confined nanostructures can be tuned (e.g., prepared to have various characteristics or parameters) in order to independently optimize various characteristics of the electron beam emitted by the photocathode. For example, by changing the material composition, size and geometry of the quantum confined nanostructures, the energy levels of the quantum confined nanostructures in the photoemission layer can be tuned to provide a photocathode having a high quantum efficiency, low emittance, fast response time to incident light pulses, long operational lifetime, and increased environmental stability compared with conventional photocathodes and cathodes in vacuum electronic devices.