Novel flexible inkjet-printed Metal-Insulator-Semiconductor organic diode employing silver electrodes

The fabrication of diodes by inkjet printing has been hampered by difficulties in printing low work function metals required to establish Schottky barriers with organic semiconductors. This limitation has been a major roadblock in the use of inkjet printing technology for the development of organic rectifying diodes. This paper presents the fabrication and characterization of a novel inkjet-printed metal- organic insulator- organic semiconductor diode on flexible plastic substrates. The structure consists of a polymeric insulator/semiconductor interface sandwiched between two silver electrodes. It is proposed that the rectification properties are due to a voltage controlled leakage current across the insulator/semiconductor interface. The current across the insulator is caused by the formation of a semiconductor brush-like morphology into the underneath porous insulator layer. The carrier injection into the insulator follows a thermionic emission model. Temperature dependent measurements reveal an interfacial barrier height between 0.97 eV and 0.36 eV depending on the morphology and type of insulator layer used. Metal- organic insulator- organic semiconductor based diodes show rectification ratios up to 150 at |10V| and a current density up to approximately 1 μAcm−2. The simple fabrication process of the diodes also makes it advantageous for scaling up to roll-to-roll production.