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In this paper, a sidelobe recognition method using boresight error and quadrant signal difference for a monopulse array is proposed. A conventional sidelobe recognition method compares the difference between the sum and delta channels. This method works well for the azimuth and elevation planes. However, the method is prone to many errors in the diagonal region of the two-dimensional plane. To overcome this problem, a method to calculate the deviation of the boresight error difference with different frequency combinations and a threshold to identify the sidelobe is proposed, and the method is validated to significantly reduce the error region. If a four-quadrant signal can be extracted separately, the signal deviation can be calculated and compared with the threshold, and the error region can be further reduced. The effects of each margin and bandwidth on the recognition performance are analyzed, and a slot array antenna is simulated to assess the method’s effectiveness.

Abstract The light‐emitting dipole orientation (EDO) of a phosphorescent emitter is a key to improving the external quantum efficiency (EQE) of organic light‐emitting diodes (OLEDs) without structural modification of the device. Here, four homoleptic Ir complexes as a phosphorescent emitter are systematically designed based on the molecular structure of tris(2‐phenylpyridine)iridium(III) (Ir(ppy)3) to control the EDO. Trimethylsilane, methyl, 2‐methylpropyl, and cyclopentylmethyl group substituted to pyridine ring of the ligand contribute to the improvement of the EDO from 76.5% for Ir(ppy)3 to 87.5%. A linear relationship between the EDO and the aspect ratio (geometric anisotropy factor) is founded, implying the importance of the effective area for the nonbonding force between host and dopant molecules. Also, it is investigated that the EDO enhancement mainly originates from the vertical alignment of the C3 axis of molecule in the substrate axis rather than the change in the direction of the transition dipole alignment in the molecular axis. The optical simulation reveals that the outcoupling efficiency of phosphorescent OLEDs adopting new dopants reaches 38.4%. The green OLEDs exhibiting 28.3% of EQE, 103.2 cd A–1 of current efficiency, and 98.2 lm W–1 of power efficiency are demonstrated, which is understood to have little electrical loss.

Though Ir-based dopants with ancillary ligands are attractive for realizing efficient organic light-emitting diodes, a strategy for designing these materials remains elusive. Here, the authors report a design strategy for heteroleptic triplet OLED emitters featuring functionalized ancillary ligands.

Carbon dots (C-dots) are a promising class of carbonaceous nanomaterials for bioimaging, catalysis, and optoelectronics. However, their applications are disrupted by recent reports that bright molecular fluorophores are co-produced in the synthesis of C-dots, in particular ones prepared through a bottomup approach (carbon nanodots (CNDs)), commonly derived from citric acid precursors. The presence of highly emissive molecular fluorophore species obscures the true performance of CNDs and severely challenges the development of CNDs. Here we observe that the issue of molecular fluorophore impurity is still problematic for CNDs which are derived from a different type of precursor, polycylic aromatic hydrocarbons (PAHs). In this study, low-oxygen-content CNDs and small molecular fluorophores are co-produced through hydrothermal condensation of nitropyrene. Extensive and systematic characterization following column chromatographic separation and solvent-induced extraction reveals that molecular fluorophores and CNDs are clearly dissimilar in structure and optical properties. This work highlights that rigorous separation and purification steps need to be taken not only for hydrophilic CNDs but also for low-oxygen-content CNDs. [ABSTRACT FROM AUTHOR]

This study proposes a modeling process of equivalent terrains to reduce the computational load and time of a full-wave electromagnetic (EM) simulation. To verify the suitability of the proposed process, an original terrain model with a size of 3 m × 3 m is equivalently quantized based on the minimum range resolution of a radar, and the radar image of the quantized model is compared with that of the original model. The results confirm that the simulation time can be reduced from 407 hours to 162 hours without a significant distortion of the radar images, and an average estimation error of the quantized model (20.4 mm) is similar to that of the original model (20.3 mm). [ABSTRACT FROM AUTHOR]