Potassium Iodide, 10 Percent (w/v) Aqueous Solution is refered to by the chemical formula KI and is an inorganic compound. Used as a component in film photography before the discovery of silver iodide, it is also used in the electrolyte of dye sensitized solar cells. KI is also used as an emergency blockade of radio-iodine, a common form of radiation poisoning.