Alternating Current Thin Film and Powder Electroluminescence

Alternating current (AC) electroluminescent light emitting materials and devices play a small but continuing role in today's solid state lighting and display markets. The semiconductor‐based solid state conversion of electrical energy to visible light has become dominated by both inorganic and organic p‐n junction light emitting diode (LED) devices, however there are other mechanisms of effecting luminescence from electron‐hole pair recombination in devices that do not necessarily have both p‐type and n‐type regions. In contrast to organic light emitting diode (OLED) devices, powder electroluminescence (EL) and thin film electroluminescence (TFEL) materials are relatively air and moisture insensitive due to their use of inorganic crystalline materials. The use of free‐standing and self‐supporting ceramic sheets for EL substrates has been employed to develop a number of new EL phosphors. The device structure is effectively composed of numerous spherical, small‐area TFEL devices embedded within a polymer film.