Probing bulk transport and interfacial disorders of amorphous organic semiconductors in a thin film transistor configuration

Organic semiconductors are finding widespread applications in modern optoelectronic devices. So far, organic light-emitting diodes (OLEDs), lighting and display applications have captured the most attention. In these devices, organic semiconductors are usually present in the form of amorphous films. Thus, there are numerous endeavors to develop new amorphous materials for OLED applications, and improving their intrinsic conductivities is of vital importance for the reduction of power consumption and device optimization.[1] We propose here to use organic thin film transistor (TFT) technique as a low-sample-demand tool for probing bulk transport properties of these amorphous organic semiconductors. To do this, the gate dielectric layer for the TFT structure needs to be non-polar. The non-polar surface can be realized through deposition of suitable non-polar polymers or organic insulators. On such a surface, we suggest that bulk-like behaviors can be realized for amorphous organic semiconductors. We highlight that only a thin film down to ~10 nm is sufficient for TFT measurements. Thus our approach will be of special relevance to the evaluation of transport properties of newly synthesized materials in which the yield is yet to be optimized. We also point out that the TFT can serve as a tool to study gate dielectric / organic interaction. Through temperature dependent measurements, interfacial energetic disorder can be evaluated. The outcome of this project should signify a key advance in the transport characterization of organic semiconductors and is of general interest to the research community of organic electronics.