Narrowband thermal emission at high temperatures is required for various thermal energy systems. However, the large lossy energy of refractory metals induces a broad bandwidth emission. Here, we demonstrated a two-dimensional (2D) superlattice microcavity array on refractory metals to control the emission bandwidth. A hybrid resonance mode was obtained by coupling the standing-wave modes and propagating surface-wave modes. The bandwidth emission was controlled by varying the superlattice microcavity array resulting from the change in electric field (E-field) concentration. The quality factor (Q-factor) improved by more than 3 times compared to that of a single-lattice array. A narrower band emission originating from the hybrid mode was observed and analyzed experimentally. This novel surface-relief microstructure method can be used to control the emission bandwidth of thermal emitters used in thermophotovoltaic (TPV) systems and other high-temperature thermal energy systems.
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http://dx.doi.org/10.1364/OE.455722 | DOI Listing |
Chemistry
January 2025
University of Delaware, Chemistry and Biochemistry, UNITED STATES OF AMERICA.
We describe synthesis of BN-doped nanographene containing five phenylene units, boron and nitrogen atoms with both alternating ortho-disposition as well as direct B-N connection. Resulting BN doped nanographene exhibits blue fluorescence at 441 nm with extraordinary narrow fluorescence peak with full width at half maximum (FWHM) = 10-11 nm. Crystallography reveals supramolecular organization of this compound in the crystal phase.
View Article and Find Full Text PDFTerahertz (THz) generation via photomixing on photoconductive antenna using twin delayed chirped pulses provides a long THz pulse with a narrow bandwidth. To generate a long pulse with a broad bandwidth, we propose a new, to the best of our knowledge, method that combines two long optical pulses with opposite chirps. The pulses exhibit temporal distributions of their instantaneous frequencies with opposite slopes.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
January 2025
Key Lab of Organic Optoelectronics and Molecular Engineering of Ministry of Education, Department of Chemistry, Tsinghua University, Beijing, 100084, P. R. China.
Expanded heterohelicenes composed of alternating linearly and angularly fused multi-resonance (MR) skeletons have gained wide interest owing to their promising narrowband emissions. Herein, a pair of sym- and asym-expanded heterohelicene isomers was obtained by merging boron/oxygen (B/O)-embedded MR triangulene and indolo[3,2,1-jk]carbazole units via one-pot synthesis. Owing to their fully resonating extended helical skeleton, the target heterohelicenes exhibit a significantly narrowed spectra bandwidth while emission red-shifting, thus affording deep-blue narrowband emission with a peak at approximately 460 nm, full-width-at-half-maximum (FWHM) of only 18 nm, and near-unity photoluminescence quantum yields.
View Article and Find Full Text PDFSci Rep
January 2025
Nanyang Technological University, Singapore, 639798, Singapore.
Although electric vehicles supplied through distributed generators (DGs) have been universally researched to reduce CO emissions, the accurate current sharing regarding islanded multi-bus DC charging stations considering three charging modes of electric vehicles, i.e., constant current mode, constant power mode and constant voltage mode, is rarely realized.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
January 2025
Center for Bioinspired Science and Technology, Hangzhou International Innovation Institute, Beihang University, Hangzhou, 311115.
Achieving multi-spectrum compatible stealth in radar-terahertz-infrared bands with robust performance has great prospects for both military and civilian applications. However, the progress of materials encounters substantial challenges due to the significant variability in frequency coupling properties across different electromagnetic wave bands. Here, this work presents the design of a multi-scale structure and fabricates a lightweight aerogel (silver nanowire@carbon, AgNW@C) consisting of a regular coaxial nano-cable, with silver nanowire as the core and amorphous-graphitized hybrid carbon as the outer-layer.
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