Characteristics Of Organic Devices Research Articles

Role of Injection Barrier in Capacitance-Voltage Measurements of Organic Devices

Capacitance-voltage (C-V) measurements represent a very useful technique, however, its usage in organic devices has been a subject of debate because of the role played by the ambient-induced unintentional doping. In this letter, we show that, contrary to the current understanding, prolonged ambient exposure does not significantly increase the unintentional doping density of organic semiconductors (OSCs). Our C-V measurements and detailed numerical simulations clearly indicate that the observed dispersion in C-V characteristics can be attributed to the variation in the carrier injection barrier at the OSC/electrode interface. An analytical relation between the injection barrier and the response time is derived to describe the C-V characteristics of organic devices.

Metal–organic interfaces at the nanoscale

In this work, we present an investigation of the Ag–PPP (polyparaphenylene)interface using ballistic electron emission microscopy. Our work is the first successfulapplication of the BEEM technique to metal–organic interfaces. We observe nanometrescale injection inhomogeneities. They have an electronic origin, since we findcorresponding Schottky barrier variations. We also determine the transmissionfunction of the Ag–PPP interface and find that it agrees qualitatively with thetheoretical calculations for a metal–phenyl ring interface. We conclude that chargetransport across inhomogeneous barriers needs to be considered to understandelectronic transport across metal–organic interfaces and organic device characteristics.

Thin film transistors based on organic conjugated semiconductors

The use of organic semiconductors as active layers in thin films has raised, in recent years, much interest, both for the fundamental understanding of the charge transport processes in organic materials, and for the potential applications of these devices in the new field of flexible electronics. The actual state of the art indicates that the characteristics of organic devices have become compatible with those of amorphous silicon based ones. What have been the major steps achieved in this research, and how far could progress still lead?