Disclosed herein is an organic thin film transistor comprising a substrate,
a gate electrode, a gate insulating layer, an organic semiconductor layer, source-drain
electrodes and a protective layer wherein a buffer layer is interposed between
the organic semiconductor layer and the protective layer. Such a transistor minimizes
the deterioration in the performance of the transistor due to ambient air containing
oxygen and moisture, and the degeneration in the performance of the transistor
caused during mounting a display device.