Search

As one of the most appealing two-dimensional materials, graphene (Gr) has attracted tremendous research interest in optoelectronic device applications for its plenty of exceptional electrical and optical properties. The emergence of Gr/semiconductor hybrid heterostructures provides a promising platform for assembling high-performance optoelectronic devices that can overcome intrinsic limitations of Gr. However, although significant achievements have been made, many challenges still exist. Here, we comprehensively review the progress in the development of various optoelectronic devices based on Gr/semiconductor hybrid heterostructures, including /group II-VI nanostructures, /group III-V semiconductors, /group IV semiconductors, /metal oxides and /other semiconductors, in terms of the device design, device performance and physics, processing techniques for performance optimization, etc . In the final section, conclusions of the existing techniques are presented and future challenges in optoelectronic applications of Gr/semiconductor hybrid heterostructures are addressed. [ABSTRACT FROM AUTHOR]

Following a significant number of graphene studies, other two-dimensional (2D) layered materials have attracted more and more interest for their unique structures and distinct physical properties, which has opened a window for realizing novel electronic or optoelectronic devices. Here, we present a comprehensive review on the applications of 2D-layered semiconductors as photodetectors, including photoconductors, phototransistors, and photodiodes, reported in the past five years. The device designs, mechanisms, and performances of the photodetectors are introduced and discussed systematically. Emerging techniques to improve device performances by enhancing light-matter interactions are addressed as well. Finally, we deliver a summary and outlook to provide a guideline of the future development of this rapidly growing field. [ABSTRACT FROM AUTHOR]

Flexible and light weight perovskite solar cells have attracted much attention recently for their broad potential applications especially in wearable electronics. However, highly flexible devices cannot be realized with the conventional transparent electrodes based on conductive oxides since they are rigid and brittle. Here, we demonstrate the fabrication of ultrathin and flexible perovskite solar cells with graphene transparent electrodes for the first time. The flexible devices with the structure of polyethylene terephthalate/graphene/poly(3-hexylthiophene)/CH 3 NH 3 PbI 3 /PC 71 BM/Ag are prepared on 20 µm-thick polyethylene terephthalate substrates by low-temperature solution process, which show the power conversion efficiency of 11.5% and high bending durability. Moreover, the devices demonstrate the power output per weight (specific weight) of about 5 W/g, which is much higher than those of conventional inorganic solar cells. This work paves a way for preparing flexible perovskite solar cells as well as other optoelectronic devices by using graphene transparent electrodes. [ABSTRACT FROM AUTHOR]

Metal nanoparticles (NPs) induced surface plasmon resonance (SPR) is of great interest for efficient controlling over light׳s propagation and absorption in optoelectronic devices applications. In this work, we proposed a simple strategy to improve the photocurrent of planar silicon (Si) p–n junction solar cells by attaching plasmonic Au nanoparticles (AuNPs) onto transparent graphene film to enhance incident light harvesting. Finite Element Method based simulations reveal that the strong light scattering by AuNPs is responsible for the optical absorption enhancement within Si, leading to the increase in photocurrent. In addition, decoration of AuNPs on graphene also contributes to a high fill factor ( FF ) by reducing series resistance in the circuit. These contributory factors, together with the effective surface passivation of Si yield a power conversion efficiency (PCE) as high as 10.15%, with excellent reproducibility. This study will open up new opportunities for the optimization of Si based optoelectronic devices. [ABSTRACT FROM AUTHOR]

The volume fraction of functionalized graphene nanoplatelets (GNPs) influencing on the thermal conductivities of GNPs/polyphenylene sulfide (GNPs/PPS) composites are investigated. Results reveal that a great improvement of the thermal conductivities with the addition of functionalized GNPs, and the thermal conductivity of the GNPs/PPS composite is 4.414 W/mK with 29.3 vol% functionalized GNPs, 19 times higher than that of the pure PPS matrix. The significantly high improvement of the thermal conductivities is ascribed to good thermal transmission through GNPs networks in the PPS matrix, following a thermal percolation behavior. Meantime, the GNPs have strong ability to generate continuous thermally conductive chains, and the formation of thermally conductive networks becomes much easier. POLYM. COMPOS., 35:1087-1092, 2014. © 2013 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Schottky junctions made from a titanium dioxide nanotube (TiO2NT) array in contact with a monolayer graphene (MLG) film are fabricated and utilized for UV light detection. The TiO2NT array is synthesized by the anodization and the MLG through a simple chemical vapor deposition process. Photoconductive analysis shows that the fabricated Schottky junction photodetector (PD) is sensitive to UV light illumination with good stability and reproducibility. The corresponding responsivity ( R), photoconductive gain ( G), and detectivity ( D*) are calculated to be 15 A W−1, 51, and 1.5 × 1012 cm Hz1/2 W−1, respectively. It is observed that the fabricated PD exhibits spectral sensitivity and a simple power-law dependence on light intensity. Moreover, the height of the Schottky junction diode is derived to be 0.59 V by using a low temperature I-V measurement. Finally, the working mechanism of the TiO2NT array/MLG film Schottky junction PD is elucidated. [ABSTRACT FROM AUTHOR]

Graphene wrapped nitrogen-doped active carbon fibers (ACF@GR) of a core-shell structure were successfully prepared by a simple dip-coating method using natural silk as template. Compared to pure silk active carbon, the as-prepared ACF@GR composites exhibit high specific surface area in a range of 1628–2035 m 2 g −1 , as well as superior energy storage capability, an extremely high single-electrode capacitance of 552.8 F g −1 was achieved at a current density of 0.1 A g −1 in 6 M KOH aqueous electrolyte. The assembled aqueous symmetric supercapacitors are capable of deliver both high energy density and high power density, for instance, 17.1 Wh kg −1 at a power density of 50.0 W kg −1 , and 12.2 Wh kg −1 at 4.7 kW kg −1 with a retention rate of 71.3% for ACF@GR1-based supercapacitor. [ABSTRACT FROM AUTHOR]

• MnO 2 /GO nano-hybrids were fabricated under mild conditions. • More than 91% norfloxacin was degraded within 20 min. • The mineralization rates of norfloxacin could reach to 76%. • Possible degradation pathways were proposed. In this work, 1D MnO 2 nano-needles were prepared and grown on the graphene oxide (GO) nano-sheets successfully. The morphology and structure of materials were explored. The MnO 2 nano-needles with a length of 200–400 nm were distributed uniformly on the GO nano-sheets. As a result of GO substrate, the MnO 2 /GO nano-hybrids (MnO 2 /GO) have the much larger surface area and more surface oxygen-containing functional groups than MnO 2 nano-needles, which are beneficial for enrichment and degradation of the norfloxacin (NOR). Results showed that more than 80% NOR was degraded within 20 min at the dose of 10 mM PMS and 0.8 g/L catalysts. Moreover, the optimal pH in MnO 2 /PMS and MnO 2 /GO/PMS system were both acidic condition. Furthermore, the mechanism of PMS activation by MnO 2 /GO was investigated through radical identification using quenching experiments and EPR techniques. According to this, the HSO 5 − of PMS reacted with Mn (IV)/Mn(III) to form a redox loop, and GO played an important role in the degradation process. Finally, the transformation intermediates of NOR were identified and four probable degradation pathways were speculated. This work would provide a potential contribution towards NOR removal in the environmental remediation. [ABSTRACT FROM AUTHOR]

Sandwich-like nitrogen-enriched porous carbon/graphene composites were prepared by carbonization of polyacrylonitrile (PAN) nanofiber paper with bulk-doped and/or surface-coated graphene oxide (GO), and followed by activation with KOH at high temperatures. The composites exhibit high specific surface areas in a range of 1957.2–2631.8 m 2 g −1 , as well as superior energy storage capability as electrodes for supercapacitors. A very high specific capacitance of 381.6 F g −1 at a current density of 0.1 A g −1 was achieved in 6 M KOH aqueous electrolyte for N-ACGrF@Gr1 that contains two types of graphene. According to the investigation results, the surface-coated graphene plays a more positive effect on improved supercapacitance than the bulk-doped graphene in the composites. Additionally, the assembled aqueous symmetric supercapacitors deliver a high energy density of 13.2 W h kg −1 at a power density of 25.0 W kg −1 , and 8.3 W h kg −1 at 4.7 kW kg −1 with a retention rate of 62.9%. [ABSTRACT FROM AUTHOR]

• A Si-SiC low temperature bonding process based on graphene composite slurry interlayer is developed. • Ar Plasma is used to treat the surface of Si and SiC to improve the bonding strength. • Bonding mechanism is explained. Recently, silicon carbide (SiC) has replaced silicon (Si) as a potential material for next-generation power devices. In this study, a Si-SiC low-temperature bonding method based on graphene composite slurry as an interlayer was developed. Ar plasma was used to treat the surfaces of Si and SiC to improve surface hydrophilicity for higher strength bonding. With the increase of discharge power, the root-mean -square (RMS) surface roughness of Si and SiC has obviously increased and the bonding quality was also greatly improved. For 70 W discharge power, the RMS surface roughness values of Si and SiC were 3.22 nm and 1.67 nm respectively, and the bonding strength reached approximately 10 MPa. Through SEM interface analysis, it can be found that a seamless bonding interface was obtained using this bonding process. [ABSTRACT FROM AUTHOR]