A light-emitting device includes a first electrode, an emission layer, an electron transport layer, a metal-nucleation inducing layer, and a second electrode. The metal-nucleation inducing layer is in direct contact with the second electrode, and includes a metal-nucleation inducing material having at least one metal-nucleation inducing group. The second electrode includes a metal-containing film that is hybridized with the metal-nucleation inducing material. The metal-nucleation inducing group is a electron-deficient nitrogen-containing C.sub.1-C.sub.60 cyclic group that is unsubstituted or substituted with at least one R.sub.1 or a group represented by one of Formulae 1A to 1E, and does not comprise a group represented by *C(O)(OH) and a cyano group. The emission efficiency and/or lifespan of the light-emitting device may be improved because of the metal-nucleation inducing layer.

A narrow band red phosphor may have a general composition MS.sub.xSe.sub.yA.sub.z:Eu, wherein M is at least one of Mg, Ca, Sr and Ba, A is at least one of C, N, B, P and a monovalent combining group NCN (cyanamide), and may in some embodiments further include one or more of O, F, Cl, Br and I. In embodiments 0.8<x+y<1.25 and 0<z0.05, and in some embodiments x, y and z are determined strictly by charge balancing. A white light emitting device may comprise: a blue and/or UV excitation source; a narrow band red phosphor of the present invention; and phosphors with peak emission at shorter wavelengths, such as yellow, green, yellow/green and/or blue.

Compound semiconductors, expressed by the following formula: Bi.sub.1-xM.sub.xCu.sub.wO.sub.a-yQ1.sub.yTe.sub.b-zQ2.sub.z. Here, M is at least one element selected from the group consisting of Ba, Sr, Ca, Mg, Cs, K, Na, Cd, Hg, Sn, Pb, Eu, Sm, Mn, Ga, In, Tl, As and Sb; Q1 and Q2 are at least one element selected from the group consisting of S, Se, As and Sb; x, y, z, w, a, and b are 0x<1, 0<w1, 0.2<a<4, 0y<4, 0.2<b<4 and 0z<4. These compound semiconductors may be used for various applications such as solar cells or thermoelectric conversion elements, where they may replace compound semiconductors in common use, or be used along with compound semiconductors in common use.

A quantum dot includes a seed and a core enclosing the seed. The core is grown from the seed to improve size uniformity of the core. The seed includes a first compound without Cd. The first compound may be GaP. The core may include a second compound including elements from group XIII and group XV. The second compound may be InP. The quantum dot may also include a first shell of a third compound enclosing the core. The third compound may be ZnSe or ZnS. The quantum dot may also include a second shell of a fourth compound enclosing the first shell. The fourth compound may be ZnS when the third compound is ZnSe. Embodiments also relate to a quantum dot including first to third elements selected from XIII group elements and XV group elements and fourth to sixth elements selected from XII group elements and XVI group elements.

A quantum dot includes a seed and a core enclosing the seed. The core is grown from the seed to improve size uniformity of the core. The seed includes a first compound without Cd. The first compound may be GaP. The core may include a second compound including elements from group XIII and group XV. The second compound may be InP. The quantum dot may also include a first shell of a third compound enclosing the core. The third compound may be ZnSe or ZnS. The quantum dot may also include a second shell of a fourth compound enclosing the first shell. The fourth compound may be ZnS when the third compound is ZnSe. Embodiments also relate to a quantum dot including first to third elements selected from XIII group elements and XV group elements and fourth to sixth elements selected from XII group elements and XVI group elements.

A cadmium free quantum dot including a core including a first semiconductor nanocrystal, and a semiconductor nanocrystal shell disposed on the core, a composition of the semiconductor nanocrystal shell being different from a composition of the first semiconductor nanocrystal, a production method thereof, and a device including the same are disclosed. The semiconductor nanocrystal shell includes a zinc chalcogenide, the zinc chalcogenide includes selenium, tellurium, sulfur, or a combination thereof, and the quantum dot further alkaline an alkaline earth metal.

A light-emitting element includes: a first electrode; a second electrode; and a quantum-dot layer; provided between the first electrode and the second electrode. The quantum-dot layer contains a plurality of quantum dots including at least cores, and an inorganic filler material filling spaces between the plurality of quantum dots. At least a portion of a composition of the quantum-dot layer around at least one core has a concentration gradient in a direction from toward a center of the core to toward around the core.