Organic Field-Effect Transistor Fabricated on Internal Shrinking Substrate

In the development of flexible organic field-effect transistors (OFET), downsizing and reduction of the operating voltage are essential for achieving a high current density with a low operating power. Although the bias voltage of the OFETs can be reduced by a high-k dielectric, achieving a threshold voltage close to zero remains a challenge. Moreover, the scaling down of OFETs demands the use of photolithography, and may lead to compatibility issues in organic semiconductors. Herein, a new strategy based on the ductile properties of organic semiconductors is developed to control the threshold voltage at close to zero while concurrently downsizing the OFETs. The OFETs are fabricated on prestressed polystyrene shrink film substrates at room temperature, then thermal energy (160 °C) is used to release the strain. The OFETs conformally attached to the wrinkled structure are shown to locally amplify the electric field. After shrinking, the horizontal device area is reduced by 75%, and the threshold voltage is decreased from −1.44 to −0.18 V, with a subthreshold swing of 74 mV dec⁻¹ and intrinsic gain of 4.151 × 10⁴. These results reveal that the shrink film can be generally used as a substrate for downsizing OFETs and improving their performance.