ABSTRACT
In recent years, the demand for near-infrared phosphor-converted light-emitting diodes (NIR pc-LEDs) has increased rapidly, leading to more and more attention being paid to the research of broad-band near-infrared phosphors. In this work, Cr3+-doped Ca2LuScGa2Ge2O12 (CLSGG:Cr3+) phosphors with broad-band NIR emission were prepared through traditional high-temperature solid-state reactions. The crystal structures of the phosphors were analyzed by X-ray diffraction (XRD) and Rietveld refinement. The photoluminescence excitation (PLE) spectra of the synthesized CLSGG:Cr3+ phosphors exhibit a strong absorption band in the 400-500 nm region, which matches well with a blue-light-emitting chip. The photoluminescence (PL) spectra of the phosphors show broad-band emission ranging from 650 to 1100 nm with a full width at half-maximum (fwhm) of about 150 nm. At 423 K, the integrated emission intensity of CLSGG:0.02Cr3+ is about 59% of that at room temperature. A NIR pc-LED device was fabricated by combining a mixture of as-synthesized CLSGG:0.02Cr3+ phosphor and silicone with a 460 nm blue-light-emitting chip. Under a driving current of 100 mA, the output power of the device can achieve 1.213 mW, indicating that the as-prepared phosphors are promising for NIR pc-LED applications.
ABSTRACT
Searching for novel photocatalysts is one of the most important topic in photocatalytic fields. In the present work, we propose a feasible approach to improve the photocatalytic activities of 2D bilayers through surface decoration, i.e. hydrogenation, halogenation, and hydroxylation. Our investigations demonstrate that after surface modification, the optical adsorption expands into the visible region, while a built-in electric field is induced due to the interlayer coupling, which can promote the charge separation for photogenerated electron-hole pairs. Our results show that the indirect-direct band gap transition of SiC, SnC, BN and GaN can be realised through adatom decoration. Furthermore, the surface-modified 2D bilayers have suitable VBM and CBM alignments with the oxidation and reduction potentials for water splitting, suggesting powerful potentials in energy and environmental applications.
ABSTRACT
Among the many novel photocatalytic systems developed in very recent years, plasmonic photocatalytic composites possess great potential for use in applications and are one of the most intensively investigated photocatalytic systems owing to their high solar energy utilization efficiency. In these composites, the plasmonic nanoparticles (PNPs) efficiently absorb solar light through localized surface plasmon resonance and convert it into energetic electrons and holes in the nearby semiconductor. This energy transfer from PNPs to semiconductors plays a decisive role in the overall photocatalytic performance. Thus, the underlying physical mechanism is of great scientific and technological importance and is one of the hottest topics in the area of plasmonic photocatalysts. In this review, we examine the very recent advances in understanding the energy transfer process in plasmonic photocatalytic composites, describing both the theoretical basis of this process and experimental demonstrations. The factors that affect the energy transfer efficiencies and how to improve the efficiencies to yield better photocatalytic performance are also discussed. Furthermore, comparisons are made between the various energy transfer processes, emphasizing their limitations/benefits for efficient operation of plasmonic photocatalysts.
ABSTRACT
We have implanted boron (B) ions (dosage: 5×1014 cm-2) into diamond and then hydrogenated the sample by implantating hydrogen ions at room temperature. A p-type diamond material with a low resistivity of 7.37 mΩ cm has been obtained in our experiment, which suggests that the hydrogenation of B-doped diamond results in a low-resistivity p-type material. Interestingly, inverse annealing, in which carrier concentration decreased with increasing annealing temperature, was observed at annealing temperatures above 600 °C. In addition, the formation mechanism of a low-resistivity material has been studied by density functional theory calculation using a plane wave method.
