Perfluorinated polyimides (and co-polyimide) compositions, particularly films are disclosed, comprising at least 50 mole percent of a polymeric repeat unit derived from contacting 3,3',4,4'-biphenyltetracarboxylic dianhydride (BDPA) and 2,2'-bis(trifluoromethyl) benzidine (TFMB) monomers. The perfluorinated polyimide (and co-polyimide) films of the invention have an in-plane coefficient of thermal expansion (CTE) between -5 and +20 ppm/.degree. C. and a average light transmittance percent of from about 65.0 to about 99.0 (on a 75-micron thick film basis). The films of the present invention were converted to a polyimide using a chemical conversion method instead of typically employed thermal conversion step thus yielding these desirable properties. The films of the present invention can be an excellent substrate in an optical display device and can be used to replace rigid glass substrates. Finally, the polyimide films of the invention can also be used to manufacture flexible display devices (e.g., cellular phones, personal digital assistants, portable video games, laptops, and the like).