Hexagonal-boron nitride (h-BN) or "white graphene" has many outstanding properties including high thermal conductivity, high mechanical strength, chemical inertness, and high electrical resistance, which open up a wide range of applications such as thermal interface material, protective coatings, and dielectric in nanoelectronics that easily exceed the current advertised benefits pertaining to the graphene-based applications. The development of h-BN films using chemical vapor deposition (CVD) has thus far led into nucleation of triangular or asymmetric diamond shapes on different metallic surfaces. Additionally, the average size of the triangular domains has remained relatively small (∼ 0.5 μm(2)) leading to a large number of grain boundaries and defects. While the morphology of Cu surfaces for CVD-grown graphene may have impacts on the nucleation density, domain sizes, thickness, and uniformity, the effects of the decreased roughness of Cu surface to develop h-BN films are unknown. Here, we report the growth and characterization of novel large area h-BN hexagons using highly electropolished Cu substrate under atmospheric pressure CVD conditions. We found that the nucleation density of h-BN is significantly reduced while domain sizes increase. In this study, the largest hexagonal-shape h-BN domain observed is 35 μm(2), which is an order of magnitude larger than a typical triangular domain. As the domains coalesce to form a continuous film, the larger grain size offers a more pristine and smoother film with lesser grain boundaries induced defects.

Electrochromic (EC) device reversibly changes color and optical state by applying electric potential. EC materials shows color change due to redox process and electron transfer across various states under influence of electric field. EC devices are categorized based on various classes of EC materials inorganic metal oxide and polyoxometalates (POMs), metal complexes, hybrid materials, metal plasmonics–metal/alloy and organic molecules/conjugated polymers. EC materials and its viability for device application are presented herein considering various performance parameter indices. The performance of EC devices is monitored by its switching time between transparent‐bleached state to colored state and vice versa, cycling stability, coloration efficiency, applied voltage, electro‐optical properties, electrochemical stability and breakdown potentials of EC materials and electrolytes. Recent advances in the area of EC devices and materials, its operation mechanism in various categories of EC materials along with existing challenges and recommendations to improve performances and reliability are summarized.

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Large-area patterning of epitaxial graphene for Schottky junction photodetectors has been demonstrated with a simple laser irradiation method. In this method, semimetal-semiconductor Schottky junctions are created in a controllable pattern between epitaxial graphene (EG) and laser-modified epitaxial graphene (LEG). The zero-biased EG-LEG-EG photodetector exhibits a nanosecond and wavelength-independent photoresponse in a broad-band spectrum from ultraviolet (200 nm) through visible to infrared light (1064 nm), distinctively different from conventional photon detectors. An efficient external photoresponsivity (or efficiency) of ∼0.1 A·W(-1) is achieved with a biased interdigitated EG-LEG-EG photodetector. The fabrication method presented here opens a viable route to carbon optoelectronics for a fast and highly efficient photoconductive detector.