Unless otherwise indicated herein, the materials described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
Negative differential resistance (NDR) is a property of electrical circuit elements in which, over certain voltage ranges, current may be a decreasing function of voltage. NDR may be classified into broad categories of N- and S-shaped current-voltage characteristics. PN junction tunnel diodes and resonant tunneling diodes are among examples of devices that may exhibit N-shaped NDR. Thyristors are semiconducting devices that may exhibit S-type NDR. Thyristor devices may include a four layer diode of alternating n-type and p-type material and three terminals. Devices that exhibit NDR may be useful in memory and switching applications. Devices that exhibit S-type NDR may be particularly useful in applications such as inverters and motor control due to their utility to control AC current.
The use of organic semiconducting materials may be attractive because of the potential for fabrication of circuits on flexible substrates using low cost printing techniques. Organic thin-film transistors, solar cells, and light emitting diodes have improved in performance and achieved commercial success over the last decade.