With advances in exfoliation and synthetic techniques, atomically thin films of semiconducting transition metal dichalcogenides have recently been isolated and characterized. Their two-dimensional structure, coupled with a direct band gap in the visible portion of the electromagnetic spectrum, suggests suitability for digital electronics and optoelectronics. Toward that end, several classes of high-performance devices have been reported along with significant progress in understanding their physical properties. Here, we present a review of the architecture, operating principles, and physics of electronic and optoelectronic devices based on ultrathin transition metal dichalcogenide semiconductors. By critically assessing and comparing the performance of these devices with competing technologies, the merits and shortcomings of this emerging class of electronic materials are identified, thereby providing a roadmap for future development.

Emerging Device Applications for Semiconducting Two-Dimensional Transition Metal Dichalcogenides

Electron and ambipolar transport in organic field-effect transistors.

Acenes have long been the subject of intense study because of the unique electronic properties associated with their pi-bond topology. Recent reports of impressive semiconductor properties of larger homologues have reinvigorated research in this field, leading to new methods for their synthesis, functionalization, and purification, as well as for fabricating organic electronic components. Studies performed on high-purity acene single crystals revealed their intrinsic electronic properties and provide useful benchmarks for thin film device research. New approaches to add functionality were developed to improve the processability of these materials in solution. These new functionalization strategies have recently allowed the synthesis of acenes larger than pentacene, which have hitherto been largely unavailable and poorly studied, as well as investigation of their associated structure/property relationships.

The larger acenes: versatile organic semiconductors.

Organic semiconducting oligomers for use in thin film transistors.

The present invention provides stretchable, and optionally printable, semiconductors and electronic circuits capable of providing good performance when stretched, compressed, flexed or otherwise deformed. Stretchable semiconductors and electronic circuits of the present invention preferred for some applications are flexible, in addition to being stretchable, and thus are capable of significant elongation, flexing, bending or other deformation along one or more axes. Further, stretchable semiconductors and electronic circuits of the present invention may be adapted to a wide range of device configurations to provide fully flexible electronic and optoelectronic devices.

http://science.sciencemag.org/content/sci/311/5758/208.full.pdf

Stretchable form of single crystal silicon for high performance electronics on rubber substrates

We have fabricated organic thin-film transistors and ring oscillators on paper and on flexible polyetherether ketone film using small-molecule hydrocarbon pentacene as the semiconductor and solution-processed polyvinylphenol as the gate dielectric. Transistors on paper have a carrier mobility of 0.2 cm2/V s and an on/off current ratio of 106, similar to devices on polyetherether ketone. A signal propagation delay of 22 μs per stage was measured for pentacene ring oscillators on polyetherether ketone film, and a signal delay of 12 ms was obtained for ring oscillators on paper.

Organic electronics on paper

We have fabricated organic thin film transistors, inverters, and ring oscillators on glass and on flexible polyethylene naphthalate, using the small-molecule hydrocarbon pentacene as the semiconductor and solution-processed polyvinylphenol as the gate dielectric. Depending on the choice of substrate, the transistors have a carrier mobility between 0.3 and 0.7 cm2/V s, an on/off current ratio between 105 and 106, and a subthreshold swing between 0.9 and 1.6 V/decade. To account for the positive switch-on voltage of the transistors, circuits were designed to operate with integrated level shifting. Depending on the type of substrate, ring oscillators have a signal propagation delay as low as 15 μs per stage.

Pentacene organic transistors and ring oscillators on glass and on flexible polymeric substrates

We report the first organic complementary circuits on flexible substrates. Organic thin-film transistors were fabricated using pentacene as the semiconductor for the p-channel devices and hexadecafluorocopperphthalocyanine (F/sub 16/CuPc) as the semiconductor for the n-channel devices. Both semiconductors were purchased from commercial sources and deposited by evaporation in vacuum. The pentacene layer was photolithographically patterned to simplify the circuit layout and reduce the circuit area. The transistors and circuits were manufactured on thin, transparent sheets of polyethylene naphthalate. Evaporated metals were used to define all contacts and interconnects, and a 50-nm-thick layer of solution-processed polyvinylphenol was used as the gate dielectric. Transistors and circuits operate at supply voltages as low as 8 V, and ring oscillators have a signal propagation delay as low as 8 /spl mu/s per stage. To our knowledge, these are the fastest organic complementary circuits reported to date.

Flexible organic complementary circuits

The invention relates to a solution for treating a rough surface, especially a paper, which is used as a supporting material for a semiconductor component. Said solution is characterized by at least one phenol-containing basic polymer and/or copolymer. The invention also relates to a method for treating said surface with a solution, and a semiconductor component that is provided with a substrate which has been treated with a solution according to the inventive method. The invention makes it possible to arrange semiconductor components on rough surfaces.

Solution and method for the treatment of a substrate, and semiconductor component

In order to reduce the operating voltage of transistors and circuits based on organic semiconductors we have recently developed organic thin film transistors with a 2.5 nm thick molecular self-assembled monolayer (SAM) gate dielectric (1). Thanks to a large gate dielectric capacitance of 9/spl times/10/sup -7/ F/cm , these TFTs can be operated with supply voltages of less than 2 V and have a record subthreshold swing of 100mV/dec. Here we present results on the first organic inverters and ring oscillators with molecular gate dielectrics, manufactured on glass and on flexible, transparent polymeric substrates. These organic circuits operate with supply voltages as low as 1.5 V and have signal propagation delays as low as a few hundred microseconds per stage.

Florian Eder

Papers

Organic electronics on paper

Pentacene organic transistors and ring oscillators on glass and on flexible polymeric substrates

Flexible organic complementary circuits

Solution and method for the treatment of a substrate, and semiconductor component

Low-voltage flexible organic circuits with molecular gate dielectrics