Photoelectronic memory based on nitride multiple quantum wells and the hybrid of graphene nanoflakes and a-IGZO film.

Optical memories are vitally important for the future development of high speed and low cost information technologies. Current optical memory devices still suffer from difficulties such as scaling-down of size, short-life expectancy, and non-volatility without the control of a gate electrode. To resolve these obstacles, a robust photoelectronic memory device is designed and demonstrated based on the integration of amorphous InGaZnO (a-IGZO), GNSs, and nitride multiple-quantum-wells light-emitting diode (MQWs LED). Utilizing the inherent nature of the band alignment between a-IGZO and graphene nanosheets (GNSs), electrons can transfer from a-IGZO to GNSs causing a persistent photoconductivity (PPC). With the long-lasting lifetime of PPC, the signal can be written optically and the encoded signal can be read both electrically and optically. The read and write processes reveal little current degradation for more than 10,000 sec, even repeated for more than hundred times. The device can convert invisible information to visible signal, and the encoded information can be simply erased under a reversed bias without a gate electrode. In addition, the memory device possesses a simple vertically stacked structure for 3D integration, and it is compatible with established technologies.

Hybrid Optical/Electric Memristor for Light-Based Logic and Communication.

Light-based information processing has the potential to increase speed, security, and scalability of electronic devices if issues in the device complexity could be resolved. We here demonstrate an integrated nanoelectronic device that can combine, store, and manipulate optical and electronic information. Employing a mechanically flexible and multilayered structure, a device is realized that shows memristive behavior. Illumination is shown to control the device operation in several unique ways. First, the device produces photocurrent that allows us to read out the device state in a self-powered manner. More importantly, a varying light intensity modulates the switching transition in a proportional manner that is akin to a neuron with variable plasticity and which can be taught and queried using either light or electrical inputs. This behavior enables a multilevel light-controlled logic and teaching schemes that can be applied to light-based communication devices and provides a route toward ubiquitous and low-cost sensors for future internet of things applications.

Ultrahigh Sensitive and Flexible Magnetoelectronics with Magnetic Nanocomposites: Toward an Additional Perception of Artificial Intelligence.

In recent years, flexible magnetoelectronics has attracted a great attention for its intriguing functionalities and potential applications, such as healthcare, memory, soft robots, navigation, and touchless human-machine interaction systems. Here, we provide the first attempt to demonstrate a new type of magneto-piezoresistance device, which possesses an ultrahigh sensitivity with several orders of resistance change under an external magnetic field (100 mT). In our device, Fe-Ni alloy powders are embedded in the silver nanowire-coated micropyramid polydimethylsiloxane films. Our devices can not only serve as an on/off switch but also act as a sensor that can detect different magnetic fields because of its ultrahigh sensitivity, which is very useful for the application in analog signal communication. Moreover, our devices contain several key features, including large-area and easy fabrication processes, fast response time, low working voltage, low power consumption, excellent flexibility, and admirable compatibility onto a freeform surface, which are the critical criteria for the future development of touchless human-machine interaction systems. On the basis of all of these unique characteristics, we have demonstrated a nontouch piano keyboard, instantaneous magnetic field visualization, and autonomous power system, making our new devices be integrable with magnetic field and enable to be implemented into our daily life applications with unfamiliar human senses. Our approach therefore paves a useful route for the development of wearable electronics and intelligent systems.

Diverse Functionalities of Vertically Stacked Graphene/Single layer n-MoS2/SiO2/p-GaN Heterostructures.

Integrating different dimentional materials on vertically stacked p-n hetero-junctions have facinated a considerable scrunity and can open up excellent feasibility with various functionalities in opto-electronic devices. Here, we demonstrate that vertically stacked p-GaN/SiO2/n-MoS2/Graphene heterostructures enable to exhibit prominent dual opto-electronic characteristics, including efficient photo-detection and light emission, which represents the emergence of a new class of devices. The photoresponsivity was found to achieve as high as ~10.4 AW-1 and the detectivity and external quantum efficiency were estimated to be 1.1 × 1010 Jones and ~30%, respectively. These values are superier than most reported hererojunction devices. In addition, this device exhibits as a self-powered photodetector, showing a high responsivity and fast response speed. Moreover, the device demonstrates the light emission with low turn-on voltage (~1.0 V) which can be realized by electron injection from graphene electrode and holes from GaN film into monolayer MoS2 layer. These results indicate that with a suitable choice of band alignment, the vertical stacking of materials with different dimentionalities could be significant potential for integration of highly efficient heterostructures and open up feasible pathways towards integrated nanoscale multi-functional optoelectronic devices for a variety of applications.

An Arbitrary Color Light Emitter.

The integration of a light-emitting transistor based on graphene/insulator/semiconductor with downconversion emitters enables the manipulation of emitted light covering the whole chromaticity space, including white-light emission. This novel arbitrary-color light emitter offers a promising approach for new applications in optoelectronic devices ranging from displays to solid-state lighting.

Highly Stretchable and Sensitive Photodetectors Based on Hybrid Graphene and Graphene Quantum Dots.

Stretchable devices possess great potential in a wide range of applications, such as biomedical and wearable gadgets and smart skin, which can be integrated with the human body. Because of their excellent flexibility, two-dimensional (2D) materials are expected to play an important role in the fabrication of stretchable devices. However, only a limited number of reports have been devoted to investigating stretchable devices based on 2D materials, and the stretchabilities were restricted in a very small strain. Moreover, there is no report related to the stretchable photodetectors derived from 2D materials. Herein, we demonstrate a highly stretchable and sensitive photodetector based on hybrid graphene and graphene quantum dots (GQDs). A unique rippled structure of poly(dimethylsiloxane) is used to support the graphene layer, which can be stretched under an external strain far beyond published reports. The ripple of the device can overcome the native stretchability limit of graphene and enhance the carrier generation in GQDs due to multiple reflections of photons between the ripples. Our strategy presented here can be extended to many other material systems, including other 2D materials. It therefore paves a key step for the development of stretchable electronics and optical devices.