All solution-processed organic field-effect transistors with low contact resistance via interface engineering for high-performance flexible circuits

Solution-processed organic field-effect transistors (OFETs) are of great interest in both academia and industry because of the potential to reduce the production cost. However, the performance of these devices can be adversely affected by the interfacial incompatibility between solution- deposited electrodes and organic semiconductors in comparison with conventional methods. To address this critical challenge, we developed all-solution processed OFETs with low contact resistance by utilizing a multifunctional buffer layer inserted on different commercial p-type semiconductors. The buffer layer poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) is designed to effectively reduce the large Schottky barriers at the Ag/semiconductor interfaces. PEDOT:PSS also offers the function of proper affinity with Ag, resulting in the formation of hybrid PEDOT:PSS/Ag electrode patterns. High-performance poly[2,5-bis(alkyl) pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione-alt-5,5′-di(thiophen-2-yl)-2,2′-(E)-2-(2-(thiophen-2-yl)vinyl) thiophene] (PDVT-10) OFET including low contact resistance of 789 Ω cm, high average mobility of 10.5 cm² V⁻¹ s⁻¹, exceptional operational and bending stability, and a substantial enhancement in performance were realized compared to conventional methods. A pseudo-complementary inverter based on the fully solution- based and buffer layer approach was further developed, showing a voltage gain >260. Our approach can potentially overcome the device performance limitation and advance the development of low-cost, large-scale, flexible all-solution-processed OFETs.