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.

Tunneling-injection in vertical quasi-2D heterojunctions enabled efficient and adjustable optoelectronic conversion.

The advent of 2D materials integration has enabled novel heterojunctions where carrier transport proceeds thrsough different ultrathin layers. We here demonstrate the potential of such heterojunctions on a graphene/dielectric/semiconductor vertical stack that combines several enabling features for optoelectronic devices. Efficient and stable light emission was achieved through carrier tunneling from the graphene injector into prominent states of a luminescent material. Graphene's unique properties enable fine control of the band alignment in the heterojunction. This advantage was used to produce vertical tunneling-injection light-emitting transistors (VtiLET) where gating allows adjustment of the light emission intensity independent of applied bias. This device was shown to simultaneously act as a light detecting transistor with a linear and gate tunable sensitivity. The presented development of an electronically controllable multifunctional light emitter, light detector and transistor open up a new route for future optoelectronics.

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.

Electrically and optically readable light emitting memories.

Electrochemical metallization memories based on redox-induced resistance switching have been considered as the next-generation electronic storage devices. However, the electronic signals suffer from the interconnect delay and the limited reading speed, which are the major obstacles for memory performance. To solve this problem, here we demonstrate the first attempt of light-emitting memory (LEM) that uses SiO2 as the resistive switching material in tandem with graphene-insulator-semiconductor (GIS) light-emitting diode (LED). By utilizing the excellent properties of graphene, such as high conductivity, high robustness and high transparency, our proposed LEM enables data communication via electronic and optical signals simultaneously. Both the bistable light-emission state and the resistance switching properties can be attributed to the conducting filament mechanism. Moreover, on the analysis of current-voltage characteristics, we further confirm that the electroluminescence signal originates from the carrier tunneling, which is quite different from the standard p-n junction model. We stress here that the newly developed LEM device possesses a simple structure with mature fabrication processes, which integrates advantages of all composed materials and can be extended to many other material systems. It should be able to attract academic interest as well as stimulate industrial application.

All carbon-based photodetectors: an eminent integration of graphite quantum dots and two dimensional graphene.

Photodetectors with ultrahigh sensitivity based on the composite made with all carbon-based materials consisting of graphite quantum dots (QDs), and two dimensional graphene crystal have been demonstrated. Under light illumination, remarkably, a photocurrent responsivity up to 4 × 10(7) AW(-1) can be obtained. The underlying mechanism is attributed to the spatial separation of photogenerated electrons and holes due to the charge transfer caused by the appropriate band alignment across the interface between graphite QDs and graphene. Besides, the large absorptivity of graphite QDs and the excellent conductivity of the graphene sheet also play significant roles. Our result therefore demonstrates an outstanding illustration for the integration of the distinct properties of nanostructured carbon materials with different dimensionalities to achieve highly efficient devices. Together with the associated mechanism, it paves a valuable step for the further development of all carbon-based, cheap, and non-toxic optoelectronics devices with excellent performance.