A liquid crystalline medium comprises a plurality of polymerizable monomers and a plurality of liquid crystal molecules. The liquid crystal molecules are selected from at least one of compounds 1, 2, 3, 4, 5, and 6. “G1”, “G3” and “G5” are independently alkyl having 1 to 8 carbons or alkyenyl having 2 to 8 carbons. “G2” and “G6” are independently alkyl having 1 to 8 carbons or alkoxy having 1 to 7 carbons. “G4” is alkyl of 1 to 8 carbons, alkyenyl of 2 to 8 carbons or alkoxy of 1 to 7 carbons. “Z1” is single bond, ethyl or methoxy. “Z2” is single bond, ethyl, methoxy, or caroboxyl. “Z3” is single bond, ethyl, difluoromethoxy, difluoropropoxy or ethyl carboxyl. “Z4” is single bond, ethyl, difluoromethoxy, or difluoropropoxy. are independently 1,4-cyclohexylene or 1,4-phenylene. One of “E1” and “E2” is fluorine, and the other is chlorine.