Photolithographic Rugged Electrode for High-Density Low-Contact-Resistance Coplanar Organic Transistors

The realization of high-performance photolithographic coplanar organic thin film transistors (OTFTs) is fundamental to boost cosmically commercial applications of organic electronics. However, photolithographic coplanar OTFTs generally suffer from poor charge injection and therefore poor filed-effect performance. Here, a simple and effective strategy is developed to fabricate photolithographic rugged electrodes, and successfully achieve high-density low-contact-resistance photolithographic coplanar OTFTs. Based on this versatile electrode, the wafer-scale photolithographic rugged electrode can be easily achieved, and the device density of the coplanar OTFTs is as high as 28000 cm^-2 . The device shows excellent electrical properties with mobility up to 2.01 cm²  V^-1  s^-1 and R_c as low as 7.8 kΩ cm, which is superior to all the reported Ag-electrode coplanar OTFTs. This work shows a reliable strategy to reduce the contact resistance of photolithographic coplanar OTFTs and elucidates the effect of injection resistance (R_inj ) and access resistance (R_acc ) on coplanar OTFTs.