This paper reviews thin-film materials and technologies for flexible electronics and considers future applications in healthcare, the automotive industry, human-machine interfaces, mobile devices, and other environments.

The quest for low power becomes highly compelling in newly emerging application areas related to wearable devices in the Internet of Things. Here, we report on a Schottky-barrier indium-gallium-zinc-oxide thin-film transistor operating in the deep subthreshold regime (i.e., near the OFF state) at low supply voltages (<1 volt) and ultralow power (<1 nanowatt). By using a Schottky-barrier at the source and drain contacts, the current-voltage characteristics of the transistor were virtually channel-length independent with an infinite output resistance. It exhibited high intrinsic gain (>400) that was both bias and geometry independent. The transistor reported here is useful for sensor interface circuits in wearable devices where high current sensitivity and ultralow power are vital for battery-less operation.

This paper provides a review of optical devices based on a wide band-gap transparent conducting oxide (TCO) while discussing related physical mechanisms and potential applications. Intentionally using a light-induced metastability mechanism of oxygen defects in TCOs, it is allowed to detect even visible lights, eluding to a persistent photoconductivity (PPC) as an optical memory action. So, this PPC phenomenon is naturally useful for TCO-based optical memory applications, e.g., optical synaptic transistors, as well as photo-sensors along with an electrical controllability of a recovery speed with gate pulse or bias. Besides the role of TCO channel layer in thin-film transistor structure, a defective gate insulator can be another approach for a memory operation with assistance for gate bias and illuminations. In this respect, TCOs can be promising materials for a low-cost transparent optoelectronic application.

This paper reviews the current status of the ubiquitous oxide semiconductor technology for flexible and transparent interactive displays.ABSTRACT | Amorphous oxide semiconductor thin film transistors and sensors constitute fundamental building blocks for a new generation of applications ranging from interactive displays and imaging to future electronic systems that are unconstrained by form factor. This makes the quest for high mobility materials processed at low temperatures even more compelling, to enable the layering of circuits and systems on plastic and possibly even paper substrates. Transparency is also an attractive feature that enables seamless embedding of electronics for the immersive ambient. This paper reviews the current status of the ubiquitous oxide semiconductor technology for flexible and transparent interactive displays, along with demonstrated examples of continuous thin film and nanowire systems for the transistor and sensor. Issues related to photosensing and active matrix operation are discussed along with solutions addressing the problem of threshold voltage instability and its compensation for fast recovery, particularly after light stress. Physics-based compact models for expedient design and simulation of analog and digital circuits are reviewed along with examples of key system building blocks. Finally we attempt to conceptualize a thin film transistor (TFT)-based fully heterogeneously integrated and autonomous system that can be realized using a combination of oxide and other technological routes. KEYWORDS | Active matrix organic light emitting diode (AMOLED); amorphous oxide semiconductors (AOS); interactive displays; nanowire transistors; oxygen defects; thin film transistors (TFTs) Manuscript