Impact of Polymer Residue Level on the In-Plane Thermal Conductivity of Suspended Large-Area Graphene Sheets

Graphene Readout Silicon-Based Microtube Photodetectors for Encrypted Visible Light Communication

The implementation of an advanced light receiver is imperative for the widespread application of visible light communication. However, the integration of multifunctional and high-performance visible light receivers is still limited by device structure and system complexity. Herein, a graphene-readout silicon-based microtube photodetector is proposed as the receiver for omnidirectional Mbps-level visible light communication. The integration of graphene-semiconductor material systems simultaneously ensures the effective absorption of incident light and rapid readout of photogenerated carriers, and the device exhibits an ultrafast response speed of 75 ns and high responsivity of 6803 A W-1. In addition, the microtube photodetector realizes the omnidirectional light-trapping and enhanced polarization photodetection. As the receiving end of the visible light communication system, the microtube photodetector achieves a data rate of up to 778 Mbps, a field of view of 140°, and the encrypted visible light communication of polarized light, providing a new possibility for the future development of the internet of things and information security.

Emerging Flexible Thermally Conductive Films: Mechanism, Fabrication, Application

Effective thermal management is quite urgent for electronics owing to their ever-growing integration degree, operation frequency and power density, and the main strategy of thermal management is to remove excess energy from electronics to outside by thermal conductive materials. Compared to the conventional thermal management materials, flexible thermally conductive films with high in-plane thermal conductivity, as emerging candidates, have aroused greater interest in the last decade, which show great potential in thermal management applications of next-generation devices. However, a comprehensive review of flexible thermally conductive films is rarely reported. Thus, we review recent advances of both intrinsic polymer films and polymer-based composite films with ultrahigh in-plane thermal conductivity, with deep understandings of heat transfer mechanism, processing methods to enhance thermal conductivity, optimization strategies to reduce interface thermal resistance and their potential applications. Lastly, challenges and opportunities for the future development of flexible thermally conductive films are also discussed.

Defects Produced during Wet Transfer Affect the Electrical Properties of Graphene

Graphene has been widely used due to its excellent electrical, mechanical and chemical properties. Defects produced during its transfer process will seriously affect the performance of graphene devices. In this paper, single-layer graphene was transferred onto glass and silicon dioxide (SiO2) substrates by wet transfer technology, and the square resistances thereof were tested. Due to the different binding forces of the transferred graphene surfaces, there may have been pollutants present. PMMA residues, graphene laminations and other defects that occurred in the wet transfer process were analyzed by X-ray photoelectron spectroscopy and Raman spectroscopy. These defects influenced the square resistance of the produced graphene films, and of these defects, PMMA residue was the most influential; square resistance increased with increasing PMMA residue.