The main focus of development in the field of organic electronics is on light-emitting diodes, solar cells, and various types of field-effect transistors(FET). However, for sophisticated electronic circuits, not only transistors but also high-performance diodes are required, serving as key elements in rectifiers and voltage stabilizers for various circuit applications. Such devices are essential for high-frequency signal processing (e.g. RFID systems) or power conversion. Several diode parameters, such as maximum driving-current, switch-on voltage, transition frequency, on/off-ratio and non-ideality, are relevant, depending on the specific application.
Most of these parameters are closely related to the mobility of the semiconductor materials in use. Due to the anisotropy of charge carrier transport in most high-mobility organic semiconductors, the mobility is far higher in lateral devices, such as FETs, than in vertical devices, such as diodes. Therefore, it is necessary to find material systems that offer high vertical mobilities.
We present diodes targeted for rectification applications that are optimized for high current density, on/off-ratio, and switching speed. We employ a pin-diode design based on highly crystalline rubrene layers. Due to their crystallinity, these layers offer a high vertical mobility. We thoroughly studied the effect of variation in n- and p-doping on the layer properties and the resulting diodes. These devices show a very low turn-on voltage, stability of up to several 100 A cm−2 at constant power and on/off ratios of 1e6. These properties possibly allow for device operations beyond 1GHz which makes them ideal devices for signal rectification, needed for e.g. wireless communication.