Phase Separation of Polyfluorene‐Based Blend Films and Its Influence on Device Operations

Vertical phase separations have been found in blend films (TFB:F8BT) of polymer light-emitting diodes, giving rise to better device performances. A TFB wetting layer is present over most of the bottom interface with the substrate, as evidenced by the fluorescent microscopy images after top layers are etched away by oxygen plasma (see figure).