Organic thin-film transistors (OTFTs) offer unprecedented opportunities for implementation in a broad range of technological applications spanning from large-volume microelectronics and optical displays to chemical and biological sensors. In this Progress Report, we review the application of organic transistors in the fields of flexible optical displays and microelectronics. The advantages associated with the use of OTFT technology are discussed with primary emphasis on the latest developments in the area of active-matrix electrophoretic and organic light-emitting diode displays based on OTFT backplanes and on the application of organic transistors in microelectronics including digital and analog circuits.

Organic transistors in optical displays and microelectronic applications

An all-printed rectifier that can provide at least 10 V dc from a 13.56-MHz radio frequency identification (RFID) reader and an all-printed ring oscillator that can generate at least 100 Hz of clock signal to read a 96-bit RFID tag in a second under the dc power provided by the rectifier should first be printable on plastic foils for the realization of roll-to-roll (R2R) printed ultralow cost RFID tags. Here, we describe a practical way to provide all-printed and R2R-printable antenna, rectifiers, and ring oscillators on plastic foils and demonstrate 13.56-MHz-operated 1-bit RF tags. The all-printed and R2R-printable 13.56-MHz 1-bit tags can generate 102.8 Hz of clock signal as the tag approaches the 13.56-MHz RFID reader.

All-Printed and Roll-to-Roll-Printable 13.56-MHz-Operated 1-bit RF Tag on Plastic Foils

We have found that poly(benzobisimidazobenzophenanthroline) (BBL) nanobelts can be prepared by a simple high-yield, solution-phase process, which enables dispersions of the nanobelts in a large number of solvents including environmentally benign solvents such as methanol and water. Characterization of the nanobelts by transmission electron and atomic force microscopies, electron diffraction, and X-ray diffraction showed that the BBL polymer chains are oriented parallel to the long axis of each nanobelt. This unique packing motif is unlike the reported packing of polymer chains in other nanostructures, such as poly(3-hexylthiophene) nanowires, where the polymer backbone packs face-to-face along the nanowire direction. This unusual molecular packing in BBL nanobelts is explained by the rather strong intermolecular interactions, which are a result of the rigid and planar polymer chains. We investigated electron transport in single nanobelts and nanobelt networks via field-effect transistors and observed mobi...

Self-Assembly, Molecular Packing, and Electron Transport in n-Type Polymer Semiconductor Nanobelts

This article reviews recently published work concerning improved understanding of, and advancements in, organic and polymer semiconductor vapor-phase chemical sensing Thin-film transistor sensors ranging in size from hundreds of microns down to a few nanometers are discussed, with comparisons made of sensing responses recorded at these different channel-length scales The vapor-sensing behavior of nanoscale organic transistors is different from that of large-scale devices, because electrical transport in a nanoscale organic thin-film transistor depends on its morphological structure and interface properties (for example injection barrier) which could be modulated by delivery of analyte Materials used in nanoscale devices, for example nanoparticles, nanotubes, and nanowires, are also briefly summarized in an attempt to introduce other relevant nano-transducers

Nanoscale organic and polymeric field-effect transistors as chemical sensors

We have built a nonvolatile memory field-effect transistor (FET)-based on organic compounds. The gate-insulating polymer features ferroelectric-like characteristics when spun from solution into an amorphous phase. Thus, the memory transistor is built using techniques developed for organic transistors without requiring high temperature annealing steps. The memory exhibits channel resistance modulations and retention times close in performance to inorganic ferroelectric FETs (FEFETs), yet at a fraction of the cost.

Memory performance and retention of an all-organic ferroelectric-like memory transistor

A digital circuit using polymer thin-film transistors on polyester substrate is presented. The circuit consists of 171 transistors and converts a parallel word of four bits into a serial bit sequence by use of gates and flip-flops with level shifters. The integrated clock generator runs at oscillation frequencies of approximately 200 Hz with supply voltages of -25 V/+12 V. The polymer poly(3,3''-dihexyl-2,2':5',2''-terthiophene) (PDHTT) is used as semiconducting material. Measurement results for the circuit demonstrate that PDHTT can be used for digital polymer circuits.

E. Eckert

Papers

A polymer transistor circuit using PDHTT