- 标题
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Solvatochromism Study of DCM Encapsulated in ZIF-90 and the Potential Application of DCM/ZIF-90 as the Fluorescence Down-Conversion Layer for an LED Chip
摘要： In this study, we have employed the laser dye, 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (DCM), to probe the microenvironment in ZIF-90 cavities. The steady-state and time-resolved studies suggested that the ZIF-90 provides a highly restricted but solvent-accessible environment for the encapsulated molecules. Because ZIF-90 can effectively prevent the aggregation quenching of the DCM in solid state, we have employed the DCM/ZIF-90 composite material as the fluorescence down-conversion layer for the blue light-emitting diode chips. The device provides stable white light illumination with the CIE 1931 chromaticity coordinate at (0.404, 0.355). When we mixed the DCM/ZIF-90 with Ag+ ion, the Ag+ ion was reduced and formed Ag nanoparticles on the DCM/ZIF-90 surface. Our study shows that the decoration of Ag nanoparticles on the ZIF-90 surface could ultimately change the spectroscopic properties of the DCM encapsulated in ZIF-90, and this unique phenomenon can be used to tune the optical properties of the dye molecules encapsulated in the ZIF-90.
关键词： ZIF-90,fluorescence down-conversion,Ag nanoparticles,DCM,LED
更新于2025-09-23 15:19:57
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Design and Analysis of Variation in Chlorophyll and Depth for Open Ocean Underwater Optical Communication
摘要： The underwate communication is of great interest of research for many researchers because of increased dealings of human beings with world exists underwater. Underwater Commu- cation Technology (UCT) is becoming an important part of communication technologies. These include communication between divers, ships, and network system for autonomous underwater vehicles. However, optical communication with underwater exchange of infor- mation is challenged with many issues. In this paper, the attenuation for optical transmis- sion is obervsed for optical waves that are absorbing inside water, in result, suspending par- ticles and planktons produces optical scattering indirectly. In connection, underwater needs to rectify high attenuation regions for analysing ocean composition affects in Deep Ocean. This produces chlorophyll profiles that identify the attenuation in underwater communica- tion.with high attenuation. In past studies, the constant attenuation is observed irrespective of depth of occean. Furthemore, the paper address, optical attenuation for underwater com- munication via depth dependent. The system is tested for 400–700 nm and 0–250 m depth for chlorophyll concentration profile (S1–S9). The system is demonstrated via GUI devel- oped in Matlab that shows the optical attenuation at different depths underwater and along with that regions with deep chlorophyll maximum (DCM) are also shown.
关键词： Deep ocean depth,Optical attenuation,Deep chlorophyll maximum (DCM),Under water optical communication systems
更新于2025-09-23 15:19:57
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[IEEE IECON 2018 - 44th Annual Conference of the IEEE Industrial Electronics Society - D.C., DC, USA (2018.10.21-2018.10.23)] IECON 2018 - 44th Annual Conference of the IEEE Industrial Electronics Society - An Exact Time Domain Analysis of DCM Boost Mode LLC Resonant Converter for PV applications
摘要： The search for a cost feasible, optimal design of LLC converter for wide input voltage range conditions is inhibited by errors in steady state values of peak gain, tank current, tank voltage, active power etc., due to various approximations in the analysis. This leads to erroneous selection of circuit parameters. The present work provides an exact, approximation free time domain mathematical model of LLC converter operating in transformer secondary current discontinuous mode (DCM) below resonance in boost mode. The proposed approach defines voltage gain as a function of relative switching frequency (ω) and td, which represents the rectifier diode to switch conduction ratio for DCM operation. Existing works have defined voltage gain as an explicit function of quality factor (Q) and ω. The current approach leads to accurate derivation of converter voltage gain, tank RMS current, tank capacitor voltage, zero voltage switching (ZVS) angle etc. Analytical expressions are validated with simulation studies using PSIM for various inductor ratio values. A final design is verified on an experimental prototype of 320W output LLC converter designed for an input range of 20-40V for solar PV applications.
关键词： LLC,peak gain,DCM,time domain
更新于2025-09-19 17:15:36
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[IEEE 2019 IEEE 62nd International Midwest Symposium on Circuits and Systems (MWSCAS) - Dallas, TX, USA (2019.8.4-2019.8.7)] 2019 IEEE 62nd International Midwest Symposium on Circuits and Systems (MWSCAS) - Multi-Channel LED Driver with Accurate Current Matching for Portable Applications
摘要： In this paper, we present a multi-string LED driver based on a current-limiting hysteretic boost converter, which is capable of driving ten LEDs in five parallel strings. An accurate current matching circuit with low voltage headroom requirement is implemented to match currents in all LED strings. Dynamic compensation of the LED forward voltage mismatch between the strings is achieved with the introduction of a minimum voltage selector block. A PFM dimming circuit is designed to operate with a 200 kHz clock and has 11 programmable dimming ratios, ranging from 2:1 to 2048:1. This LED driver is implemented in 0.6-μm CMOS process and operates from a Li-ion battery with a voltage range 3 – 4.2 V. It is suitable for backlight LED displays in mobile devices.
关键词： dimming,hysteretic controller,DCM,current matching,LED driver,forward voltage mismatch
更新于2025-09-12 10:27:22
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Vapour‐Phase Epitaxial Growth of Dual‐Colour‐Emitting DCM‐Perylene Micro‐Heterostructure Optical Waveguides
摘要： Organic micro-heterostructures (MHS) with dual optical emissions are essential to produce miniaturized optical waveguides for wavelength division multiplexing technologies. The bimolecular MHS produced by solution-based bottom-up self-assembly technique often leads to poor surface smoothness, edge imperfection, defects, and unwanted thin films deposits. Conversely, sequential sublimation technique at ambient pressure facilitates effective integration of a-perylene micro-square with dicyano-4H-pyran methylene-2-methyl-6-(p-dimethylaminostyryl) (DCM) microrods in an epitaxial manner to produce MHS. The obtained DCM/perylene MHS act as optical waveguides to produce red (lmax (cid:2) 670 nm) or/and yellow (lmax (cid:2) 607 nm) dual optical outputs via an energy transfer mechanism depending upon the heterostructures geometry and optical excitation positions. The presented dual-color emitting MHS optical waveguides are essential for the integrated nano-photonic and optoelectronic device structures.
关键词： Micro-heterostructures,DCM,Perylene,Optical waveguides,Vapour-Phase Epitaxy
更新于2025-09-11 14:15:04