Electroluminescent device and semiconductor nanoparticle

A method of producing a semiconductor nanoparticle, which comprises:

• combining a magnesium precursor and an additive with a chalcogen precursor in a reaction medium comprising an organic solvent and an organic ligand;
• heating the reaction medium to a reaction temperature;
• and
• reacting the magnesium precursor and the chalcogen precursor in the presence of the additive to form a magnesium chalcogenide,
• wherein the semiconductor nanoparticle comprises the magnesium chalcogenide,
• wherein the magnesium chalcogenide comprises
• magnesium;
• and
• selenium, sulfur, or a combination thereof,
• wherein the additive comprises a potassium-containing hydride compound, an aluminum-containing hydride compound, a sodium-containing hydride compound, or a combination thereof, and
• wherein the semiconductor nanoparticle further comprises an alkali metal, boron, or a combination thereof.