Disclosed herein is a composite film comprising an organic polymer film; the organic polymer film having an elastic modulus of less than or equal to about 10.sup.5 gigapascals when measured at room temperature; and a bundle of carbon fibers disposed in the organic polymer film; each bundle comprising a column and an end face; each bundle also having a longitudinal axis that is substantially parallel to the column and passes through the center of the column; the end face being fibrillated so as to have a surface area measured perpendicular to the longitudinal axis that is about 110 to about 250% greater than the surface area of a cross-section of the carbon fiber measured at the column.