Ion‐Activated Greatly Enhanced Conductivity of Thin Organic Semiconducting Films in Two‐Terminal Devices

Abstract

The energetics of metal/organic semiconductor (OSC) and polymer electrolyte/OSC interfaces play a key role in the operation of a variety of electronic and optoelectronic devices. Despite extensive research in the field, the way such energetics impact on device properties is often poorly understood and overlooked. They can cause unusual phenomena as reported herein in the case of metal/OSC/electrolyte systems for which an increase of up to three orders of magnitude in the conductivity of thin OSC films is observed. Using coplanar electrode devices and OSC films made of regioregular poly(3‐hexylthiophene) (P3HT) materials, it is shown that such a phenomenon results from synergistic effects between the metal/P3HT interface energetics, charge transport, and electrolyte conductivity. The experiments make evident the existence of a thickness‐dependent electrostatic potential at the P3HT surface, which leads to ion‐assisted hole accumulation at the upper edge of the P3HT film. Together with the potential of the investigated two‐electrode devices for sensing applications, this study provides new insights for the development of electrolyte‐gated transistors and can serve as a generic method for the extraction of parameters like the space‐charge width of metal/OSC junctions.

Study of Large-area Flexible Transistor Array Fabrication

“…The temperature was set to 60 °C and stirred for about 6 hours, and after the polymer P (VDF-HFP) was completely solved, the stirring was stopped to obtain the gel solution. Then the printed semiconductor layer and the substrate after evaporation of the Au electrode are placed behind the patterned screen printing plate and aligned, and then the ionic gel printing is covered to connect the semiconductor layer and the gate electrode to complete the printing, and finally, the device is placed in the vacuum oven at 70 °C for 120 min drying [14] .…”