Abstract: A polymer electroluminescent device (1) comprises an electroluminescent layer (7) of a poly(1,4-phenylenevinylene) having aryl-1,4-phenylene units, where the aryl group is a phenyl, naphthyl or biphenylyl group. Using such a poly(1,4-phenylenevinylene) has the effect that the light emitted by the polymer electroluminescent device has no or at least a reduced tendency to change color when driven the device is and/or kept at an elevated ambient temperature of, for example, 70° C. The poly(1,4-phenylenevinylene)s having aryl-1,4-phenylene units are prepared using aryl-bishalomethylbenzenes as an intermediate compound.