The conducting homogeneity of ITO electrode and water-soluble conducting polyaniline films

The morphology and conductivity of indium/tin oxide (ITO) film have a large impact on the performance of light emitting diode (LED) devices using ITO as an anode. Atomic Force Microscope and current image tunneling spectroscopy (CITS) were used to probe the surface morphology and scanning tunneling spectroscopy (STS) of ITO surface. The morphology of all ITO films studied revealed a spherical aggregation with various grain sizes of 20 - 50 nm, depends on clean methods. It was also found that the conductivity of ITO films is related to film thickness. In general, thicker film shows higher conductivity. Nevertheless, the conductivity within a single grain is very homogeneous. On the other hand, the topographies of poly(N-(4-sulfophenyl)aniline (PSA) films revealed a rod-shaped aggregation with a diameter of 50 nm. The corresponding CITS images revealed conducting islands with irregular shape and size. The conductivity within a single polymer rod is not homogeneous.