An electro-optical device includes: (1) a first electrode layer; (2) a second electrode layer; and (3) a middle layer disposed between the first electrode layer and the second electrode layer. The middle layer includes a material having the formula: [AaBbXxX′x′X″x″], where A is selected from potassium, rubidium, and cesium; B is selected from germanium, tin, and lead; X, X′, and X″ are independently selected from fluorine, chlorine, bromine, and iodine; a is in the range of 1 to 9; b is in the range of 1 to 5; a sum of x, x′, and x″ is in the range of 1 to 9; and the material is at least one of n-doped and p-doped.