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Photo‐Organocatalytic Enantioselective Radical Cascade Enabled by Single‐Electron Transfer Activation of Allenes
摘要： Allenes are commonly used in metal-mediated transformations, cycloaddition reactions, and radical processes. However, their activation by single-electron transfer (SET) is largely underexplored. Herein, we report a visible light-driven enantioselective organocatalytic process that uses the excited-state reactivity of chiral iminium ions to activate allenes by SET oxidation. The ensuing allene cation radicals participate in stereocontrolled cascade reactions to deliver bicyclic scaffolds with good enantioselectivity and exquisite diastereoselectivity. Density Functional Theory (DFT) calculations support a mechanism that combines the peculiar chemistry of allene radical cations with polar reactivity.
关键词： photochemistry,cascade process,allene,enantioselective organocatalysis,radical chemistry
更新于2025-09-19 17:13:59
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Accurately Stoichiometric Regulating Oxidation States in Hole Transporting Material to Enhance the Hole Mobility of Perovskite Solar Cells
摘要： In the traditional n-i-p type perovskite solar cells (PSCs), most hole transporting materials (HTMs) rely on an uncontrolled oxidative process by using Li salt and Co (III) complex to achieve sufficient hole mobilities. Herein, we demonstrate a stabilized oxidized-phenothiazine-based HTM (OPTZ) synthesized from its neutral form (NPTZ) through a photo-redox reaction. This controllable and stable oxidation state is mainly derived from the planar structure and π-conjugation of phenothiazine core in OPTZ. The energy gap between SOMO (singly-occupied-molecular-orbital) of OPTZ and HOMO (highest-occupied-molecular-orbital) of NPTZ can suitably promote the hole hopping in hole transporting layers. Using an optimized ratio of OPTZ as dopant in NPTZ, the hole transporting mobility is effectively enhanced owing to intra- and inter-molecular charge transfer process, resulting in an enhancement in the fill factor of the PSCs. This work can provide a new strategy to obtain stabilized oxidized-HTMs, which deliver significantly enhanced hole mobilities of HTMs in PSCs.
关键词： phenothiazine,hole transport material,hole mobility,perovskite solar cell,radical cation
更新于2025-09-19 17:13:59
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[IEEE 2019 Photonics North (PN) - Quebec City, QC, Canada (2019.5.21-2019.5.23)] 2019 Photonics North (PN) - Exoplanetary Atmosphere Spectroscopy using Silicon Waveguide Ring Resonators
摘要： Localization is an important issue in next generation wireless networks (NGWNs), such as 5G cellular networks, IEEE 802.11ax WiFi networks, and wireless ad hoc sensor network (WASNs). This paper proposes a 3-D localization algorithm for NGWNs by utilizing the concept of radical centers from analytic geometry, and takes WASNs as an example. Assume that an unknown node can measure its distances to four or more anchor nodes (reference nodes). By picking four distance measurements to four anchor nodes, a radical center is computed. Through analytic formulation, the radical center is shown to be able to be treated as an estimation of the unknown node location. Since every four distance measurements generates one radical center (in 3-D space), to further improve and fuse these estimations, effective ?ltering mechanisms are proposed to ?lter out the improper estimations. Afterward, the remaining radical centers are averaged, and the solution is the ?nal estimation of the unknown node location. The location errors of the proposed algorithm and the conventional minimum mean square error (MMSE) method were analytically compared. It was shown that the proposed algorithm outperforms the conventional MMSE method both in accuracy and ef?ciency. Extensive computer simulations were carried out and the results veri?ed the advantage of the proposed location algorithm over the MMSE approach.
关键词： IEEE 802.11ax,radical centers,WASNs,IEEE 802.11az,5G
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE PES Asia-Pacific Power and Energy Engineering Conference (APPEEC) - Macao, Macao (2019.12.1-2019.12.4)] 2019 IEEE PES Asia-Pacific Power and Energy Engineering Conference (APPEEC) - Position Dependent Impact of Plasmonic Nanocubes on the Optical Performance of Perovskite Solar Cells: A Simulation
摘要： Localization is an important issue in next generation wireless networks (NGWNs), such as 5G cellular networks, IEEE 802.11ax WiFi networks, and wireless ad hoc sensor network (WASNs). This paper proposes a 3-D localization algorithm for NGWNs by utilizing the concept of radical centers from analytic geometry, and takes WASNs as an example. Assume that an unknown node can measure its distances to four or more anchor nodes (reference nodes). By picking four distance measurements to four anchor nodes, a radical center is computed. Through analytic formulation, the radical center is shown to be able to be treated as an estimation of the unknown node location. Since every four distance measurements generates one radical center (in 3-D space), to further improve and fuse these estimations, effective filtering mechanisms are proposed to filter out the improper estimations. Afterward, the remaining radical centers are averaged, and the solution is the final estimation of the unknown node location. The location errors of the proposed algorithm and the conventional minimum mean square error (MMSE) method were analytically compared. It was shown that the proposed algorithm outperforms the conventional MMSE method both in accuracy and efficiency. Extensive computer simulations were carried out and the results verified the advantage of the proposed location algorithm over the MMSE approach.
关键词： 5G,IEEE 802.11ax,radical centers,WASNs,IEEE 802.11az
更新于2025-09-16 10:30:52
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Demonstration of SDN-enabled Hybrid Polling Algorithm for Packet Contention Resolution in Optical Data Center Network
摘要： Localization is an important issue in next generation wireless networks (NGWNs), such as 5G cellular networks, IEEE 802.11ax WiFi networks, and wireless ad hoc sensor network (WASNs). This paper proposes a 3-D localization algorithm for NGWNs by utilizing the concept of radical centers from analytic geometry, and takes WASNs as an example. Assume that an unknown node can measure its distances to four or more anchor nodes (reference nodes). By picking four distance measurements to four anchor nodes, a radical center is computed. Through analytic formulation, the radical center is shown to be able to be treated as an estimation of the unknown node location. Since every four distance measurements generates one radical center (in 3-D space), to further improve and fuse these estimations, effective ?ltering mechanisms are proposed to ?lter out the improper estimations. Afterward, the remaining radical centers are averaged, and the solution is the ?nal estimation of the unknown node location. The location errors of the proposed algorithm and the conventional minimum mean square error (MMSE) method were analytically compared. It was shown that the proposed algorithm outperforms the conventional MMSE method both in accuracy and ef?ciency. Extensive computer simulations were carried out and the results veri?ed the advantage of the proposed location algorithm over the MMSE approach.
关键词： 5G,IEEE 802.11ax,radical centers,WASNs,IEEE 802.11az
更新于2025-09-16 10:30:52
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Solvent Engineering of a Dopant-Free Spiro-OMeTAD Hole-Transport Layer for cm-Scale Perovskite Solar Cells having High Efficiency and Thermal Stability
摘要： High efficiency and environmental stability are mandatory performance requirements for commercialization of perovskite solar cells (PSCs). Herein, efficient cm-scale PSCs with improved stability were achieved by incorporating an additive-free 2,2’,7,7’-tetrakis[N,N-di(p-methoxyphenyl)amino]-9,9’-spirobifluorene (spiro-OMeTAD) hole transporting material (HTM) through simply substituting the usual chlorobenzene solvent with pentachloroethane (PC). A stabilized power conversion efficiency of 16.1% under simulated AM 1.5G 1-sun illumination with an aperture of 1.00 cm2 was achieved for PSCs using an additive-free spiro-OMeTAD layer cast from PC. X-ray analysis suggested chlorine radicals from pentachloroethane transferred partially to spiro-OMeTAD and retain in the HTM film, resulting of conductivity improvement. Moreover, unencapsulated PSCs having cm-scale active area cast from PC retained >70% of their initial PCE after ageing at 80 °C for 500 h, in contrast with less than 20% retention for control devices. Morphological and X-ray analysis of the aged cells revealed that the perovskite and HTM layers remain almost unchanged in the cells with spiro-OMeTAD layer cast from PC whereas serious degradation occurred in the control cells. This study not only reveals the decomposition mechanism of PSCs in the presence of HTM-additives, but also opens up a broad range of organic semiconductors for radical doping.
关键词： stability,spiro-OMeTAD,perovskite solar cell,hole transporting materials,dopant-free,radical,pentachloroethane
更新于2025-09-16 10:30:52
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Guest Inclusion Modulates Concentration and Persistence of Photogenerated Radicals in Assembled Triphenylamine Macrocycles
摘要： Substituted triphenylamine (TPA) radical cations show great potential as oxidants and as spin containing units in polymer magnets. Their properties can be further tuned by supramolecular assembly. Here, we examine how the properties of photogenerated radical cations, intrinsic to TPA macrocycles, are altered upon their self-assembly into 1D columns. These macrocycles consist of two TPAs and two methylene ureas which drive the assembly into porous organic materials. Advantageously, upon activation the crystals can undergo guest exchange in a single-crystal-to-single-crystal transformation generating a series of isoskeletal host-guest complexes whose properties can be directly compared. Photoinduced electron transfer, initiated using 365 nm LED’s, affords radicals at room temperature as observed by EPR spectroscopy. The line shape of the EPR spectra and the quantity of radicals can be modulated by both polarity and heavy atom inclusion of the encapsulated guest. These photogenerated radicals are persistent, with half-lives between 1-7 days and display no degradation upon radical decay. Re-irradiation of the samples can restore the radical concentration back to a similar maximum concentration, a feature that is reproducible over several cycles. EPR simulations of a representative spectrum indicate two species, one containing two N hyperfine interactions and an additional broad signal with no resolvable hyperfine interaction. Intriguingly, TPA analogs without bromine substitution also exhibit similar quantities of photogenerated radicals, suggesting that supramolecular strategies can enable more flexibility in stable TPA radical structures. These studies will help guide the development of new photoactive materials.
关键词： photoinduced electron transfer,supramolecular assembly,radical cations,triphenylamine,EPR spectroscopy
更新于2025-09-12 10:27:22
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Antioxidant Activity of Graphene Quantum Dots Prepared in Different Electrolyte Environments
摘要： Antioxidants can reduce or inhibit damage such as oxidative decay caused by elevated levels of free radicals. Therefore, pursuing antioxidants with excellent properties has attracted more and more attention. Graphene quantum dots (GQDs) are considered a promising material because of their good free radical scavenging activity, low toxicity, and excellent water solubility. However, their scavenging e?ciency, antioxidant mechanism, and e?ective control methods need to be improved. Herein, in order to further reveal the antioxidant mechanism of GQDs, the role of electrolytes in improving the antioxidant activity of GQDs is explored. In addition, 1,1-diphenyl-2-picrazine (DPPH·), hydroxyl (·OH), and superoxide (·O2) free radicals are used to evaluate the antioxidant activity of the as-prepared GQDs. Combined with transmission electron microscopy, Fourier-transform infrared spectroscopy, Raman spectroscopy, and cyclic volt–ampere characteristic curves, the e?ects of an electrolytic environment on the surface functional groups, charge transfer capability, and defect states of GQDs are obtained. The antioxidant mechanism of GQDs and how to improve their antioxidant activity are further elucidated.
关键词： antioxidant,free radical scavenging,electrochemical method,GQDs
更新于2025-09-12 10:27:22
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Surface Carbon Shell-Functionalized ZrO2 as Nanofiller in Polymer Gel Electrolyte-Based Dye-Sensitized Solar Cells
摘要： We prepare dye-sensitized solar cells (DSSCs) fabricated with a poly (ethylene glycol) based polymer gel electrolytes (PGEs) incorporating surface carbon shell-functionalized ZrO2 nanoparticles (ZrO2-C) as nano?llers (NFs). ZrO2 are polymerized via atom transfer radical polymerization (ATRP) using poly (ethylene glycol) methyl ether methacrylate (POEM) as a sca?old to prepare the ZrO2-C through carbonization. The power conversion e?ciency of DSSC with 12 wt% ZrO2-C/PGEs is 5.6%, exceeding that with PGEs (4.4%). The enhanced e?ciency is attributed to Lewis acid-base interactions of ZrO2-C and poly (ethylene glycol), catalytic e?ect of the carbon shells of ZrO2-C, which results in reduced crystallinity, enhanced ion conductivity of electrolytes, decreased counterelectrode/electrolyte interfacial resistance, and improved charge transfer rate. These results demonstrate that ZrO2-C introduction to PGEs e?ectively improves the performance of DSSCs.
关键词： polymer gel electrolyte (PGE),zirconium dioxide (ZrO2),dye-sensitized solar cell (DSSC),nano?ller (NF),carbon,atom transfer radical polymerization (ATRP)
更新于2025-09-12 10:27:22
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Effective utilization of NIR wavelengths for photo-controlled polymerization - penetration through thick barriers and parallel solar syntheses
摘要： This contribution details an efficient and controlled photopolymerization regulated by far-red (λ = 680 nm) and NIR (λ = 780 and 850 nm) light in the presence of aluminum phthalocyanine and aluminum naphthalocyanine. Initiating radicals are generated by photosensitization of peroxides affording an effective strategy that provides controlled polymerizations of a variety of monomers with excellent living characteristics. Critically, long wavelength irradiation provides penetration through thick barriers, affording unprecedented rates of controlled polymerization that can open new and exciting applications. Furthermore, a more optimized approach to performing solar syntheses is presented. By combining the narrow Q-bands of these PCs with others possessing complementary absorptions, layered, independent polymerizations and organic transformations may be performed in parallel under a single broadband emission source such as sunlight.
关键词： Reversible-deactivation radical polymerization,Photochemistry,Photopolymerization,Solar synthesis,NIR
更新于2025-09-12 10:27:22