Charge Trapping at the Dielectric of Organic Transistors Visualized in Real Time and Space

Scanning Kelvin probe microscopy demonstrates that water-induced charge trapping at the SiO2 dielectric – visualized in real time and space – is responsible for the commonly observed gate-bias-induced threshold-voltage shift in organic field-effect transistors. When a bias is applied to the electrodes, charges are injected onto the SiO2 (see background of the figure). When the contacts are grounded, the charges are released again (foreground picture).