cesium selenide is a solid chemical compound that consists of the element cesium and the nonmetal, ionized form of selenium. It is a semiconductor and has a broad spectrum of photophysical properties.
In its elemental state, cesium is a soft silvery metal with a melting point of 28.5°C and a boiling point of 480°C. It is a member of the alkali metals and is highly reactive. It is also sensitive to moisture, oxidizing rapidly upon exposure to air and releasing toxic, brownish-yellow, superoxide gas.
The most common cesium compound is cesium chloride, a white crystalline solid that dissolves in water and acts as a strong oxidizing agent. It is able to form a wide variety of other chemicals and compounds, such as cesium nitrate, CsN, which can act as a dye and is used in pyrotechnics (fireworks). Cesium bromide, also a soluble compound, is primarily found in beamsplitters, where it is employed for its ability to separate ultraviolet from visible light.
Cesium nitrate can be modified to create the salt, cesium selenide, which is a semimetallic element with a melting point of 418°C and boiling point of 740°C. The stability of cesium selenide is attributed to its structure, with the selenium atoms bonded with oxygen ions to form a tetrahedral coordination cage. It can be stabilized by incorporating it into glass, which is a dense and inert material. The incorporation of cesium into glasses increases their thermal and chemical stabilities. This is illustrated by the fact that the PL intensity of a CsMnCl3 NCs embedded CM specimen can be almost completely recovered after ten heat-cooling cycles, while a corresponding pure CM specimen shows a significant decrease in PL intensity.