Field effect transistor including .pi.conjugate polymer and liquid crystal display including the field effect transistor

A liquid crystal display apparatus comprising:

• a driving part formed of a field effect transistor having:
• a source electrode;
• a drain electrode;
• a semiconductor layer serving as a current path between said source and drain electrodes and formed of a .pi.-conjugated polymer which is obtained from a precursor which is soluble in a solvent;
• an acid giving film disposed in contact with said semiconductor layer and producing an acid in a reaction in which said .pi.-conjugated polymer is obtained from said precursor which is soluble in the solvent;
• an insulating film disposed on said semiconductor layer;
• and
• a gate electrode disposed on said insulating film opposite from said semiconductor layer for controlling the electrical conductivity of said semiconductor layer in response to a voltage applied to said gate electrode;
• and
• a liquid crystal display part connected in series to one of said source electrode and drain electrode and controlled by applying a voltage to said gate electrode.

A field effect transistor comprising:

• a source electrode;
• a drain electrode;
• a semiconductor layer serving as a current path between said source and drain electrodes and formed of a .pi.-conjugated polymer which is obtained from a precursor which is soluble in a solvent, the .pi.-conjugated polymer having the general formula ##STR18## where R.sub.1 and R.sub.2 are one of --H, alkyl group, and alkoxyl group and n is an integer of at least 10;
• an insulating film disposed on said semiconductor layer, the insulating film producing an acid in a reaction in which the .pi.-conjugated polymer is obtained from said precursor;
• and
• a gate electrode disposed on said insulating film opposite from said semiconductor layer for controlling the electrical conductivity of said semiconductor layer in response to a voltage applied to said gate electrode.