The compelling demand for higher performance and lower power consumption in electronic systems is the main driving force of the electronics industry's quest for devices and/or architectures based on new materials. Here, we provide a review of electronic devices based on two-dimensional materials, outlining their potential as a technological option beyond scaled complementary metal-oxide-semiconductor switches. We focus on the performance limits and advantages of these materials and associated technologies, when exploited for both digital and analog applications, focusing on the main figures of merit needed to meet industry requirements. We also discuss the use of two-dimensional materials as an enabling factor for flexible electronics and provide our perspectives on future developments.

Electronics based on two-dimensional materials

Field-effect transistors based on solution-processible organic semiconductors have experienced impressive improvements in both performance and reliability in recent years, and printing-based manufacturing processes for integrated transistor circuits are being developed to realize low-cost, large-area electronic products on flexible substrates. This article reviews the materials, charge-transport, and device physics of solution-processed organic field-effect transistors, focusing in particular on the physics of the active semiconductor/dielectric interface. Issues such as the relationship between microstructure and charge transport, the critical role of the gate dielectric, the influence of polaronic relaxation and disorder effects on charge transport, charge-injection mechanisms, and the current understanding of mechanisms for charge trapping are reviewed. Many interesting questions on how the molecular and electronic structures and the presence of defects at organic/organic heterointerfaces influence the device performance and stability remain to be explored.

Device Physics of Solution‐Processed Organic Field‐Effect Transistors

At present, flexible displays are an important focus of research1,2,3 Further development of large, flexible displays requires a cost-effective manufacturing process for the active-matrix backplane, which contains one transistor per pixel One way to further reduce costs is to integrate (part of) the display drive circuitry, such as row shift registers, directly on the display substrate Here, we demonstrate flexible active-matrix monochrome electrophoretic displays based on solution-processed organic transistors on 25-μm-thick polyimide substrates The displays can be bent to a radius of 1 cm without significant loss in performance Using the same process flow we prepared row shift registers With 1,888 transistors, these are the largest organic integrated circuits reported to date More importantly, the operating frequency of 5 kHz is sufficiently high to allow integration with the display operating at video speed This work therefore represents a major step towards 'system-on-plastic'

Flexible active-matrix displays and shift registers based on solution-processed organic transistors.

Two-dimensional (2D) materials, such as molybdenum disulfide (MoS2), have been shown to exhibit excellent electrical and optical properties. The semiconducting nature of MoS2 allows it to overcome the shortcomings of zero-bandgap graphene, while still sharing many of graphene’s advantages for electronic and optoelectronic applications. Discrete electronic and optoelectronic components, such as field-effect transistors, sensors, and photodetectors made from few-layer MoS2 show promising performance as potential substitute of Si in conventional electronics and of organic and amorphous Si semiconductors in ubiquitous systems and display applications. An important next step is the fabrication of fully integrated multistage circuits and logic building blocks on MoS2 to demonstrate its capability for complex digital logic and high-frequency ac applications. This paper demonstrates an inverter, a NAND gate, a static random access memory, and a five-stage ring oscillator based on a direct-coupled transistor logic...

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Integrated Circuits Based on Bilayer MoS2 Transistors

Over the past 20 years, organic transistors have developed from a laboratory curiosity to a commercially viable technology. This critical review provides a short summary of several important aspects of organic transistors, including materials, microstructure, carrier transport, manufacturing, electrical properties, and performance limitations (200 references).

Organic thin-film transistors.

Using soluble polymers for the active layer and insulating layer, we report on a concept for the fabrication of fast integrated circuits based on p-type organic transistors only. Ring oscillators with frequencies above 100 kHz and propagation stage delays below 0.7 μs are presented. They show a very stable performance over time even without encapsulation, when stored and measured under ambient conditions. Regioregular poly(3-alkylthiophen) is used as the active semiconducting layer, a polymer blend as the insulator, a flexible polyester film as the substrate and metal electrodes. To enable vertical interconnects, the insulating layer is patterned.

Fast polymer integrated circuits

Printed organic circuits have the potential to revolutionize the spread of electronic applications. This will be enabled by inexpensive and fast fabrication with printing techniques using soluble organic materials. Two main challenges have to be mastered on the way towards printed electronics. First, the development of stable transistors and an adapted chip design for organic materials, and second, the development of a reliable fabrication process. We present our results on high performance polymer transistors, mainly based on poly-3alkylthiophene (P3AT) as semiconducting material. Fast circuits up to 200 kHz and stable circuits with operation lifetimes of more than 1000 h under ambient conditions without any encapsulation are shown. We also report on a fully printed, all organic ring oscillator.

From polymer transistors toward printed electronics

Air-stable all-polymer field-effect transistors with organic electrodes

Detailed investigations on shelf life and operation lifetime of polymer field-effect transistors (PFETs) and circuits are reported. All examined devices consisted entirely of polymer materials except the electrodes. Regioregular poly(3-alkylthiophene) was used as a semiconductor. Unencapsulated devices were produced, stored, and measured under ambient conditions. The performance of PFETs was maintained for more than 12 months after production. Even under extreme conditions of 85 °C and 85% relative humidity, a stable shelf life of more than 1400 h was measured. Transistors exceeded a continuous operation time of 1000 h. Operation lifetimes showed that the degradation did not follow the Arrhenius lifetime-temperature relationship. Similar results were found for ring oscillators.

Stability of polythiophene-based transistors and circuits

The invention relates to an antenna configuration, comprising at least one electrically insulating carrier substrate and at least one electrically conductive layer applied on at least one side of the carrier substrate, the electrically conductive layer having a first area region and a second area region, and the first area region of the electrically conductive layer having the form of at least one antenna structure. The at least one antenna structure is present in a manner electrically insulated from the second area region of the electrically conductive layer, and the second area region of the electrically conductive layer is subdivided, at least in regions directly adjacent to the at least one antenna structure, into island regions that are at least electrically insulated from one another. The at least one antenna configuration is suitable for use for contactlessly coupled transponders, in particular for RFID Tags or Smart Tags.

Jürgen Ficker

Papers

Fast polymer integrated circuits

From polymer transistors toward printed electronics

Air-stable all-polymer field-effect transistors with organic electrodes

Stability of polythiophene-based transistors and circuits

Antenna configuration and use thereof