Article comprising an organic thin film transistor

An article comprising a thin film transistor comprising

• a) a layer of organic material;
• b) spaced apart first and second contact means in contact with said layer of organic material;
• c) third contact means that are spaced from each of said first and second contact means and that are adapted for controlling, by means of a voltage applied to the third contact means, a current between the first and the second contact means;
• CHARACTERIZED IN THAT
• d) the layer of organic material comprises a layer of first organic material of a first conductivity type and a layer of a second organic material of a second conductivity type that is in contact with said layer of the first organic material at least in a region between said first and second contact means and forms a p-n junction therewith, the layer of the first organic material being in contact with each of the first and second contact means and being not in contact with the third contact means, wherein said first and second organic materials respectively have a first and a second energy gap between a highest occupied orbital and a lowest unoccupied orbital, and wherein said first and second organic materials are selected such that said first energy gap differs from said second energy gap.