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Synthesis and the effect of alkyl chain length on photochromic properties of diarylethene derivatives
摘要： A new class of photochromic diarylethenes bearing pyrrole and thiophene units with different length of alkyl chains at 2-position of thiophene rings have been synthesized. Their characteristics, including photochromism and fatigue resistance were investigated systematically, and each diarylethene derivative showed good photochromic properties whether in solution or in PMMA films. The alkyl group moiety was connected directly to the central cyclopentene ring as a heteroaryl unit and availably participated in photoisomerization reaction. And some properties, for example, the conversion ratio in the photostationary state(PSS) and the absorption coefficient of the ring-closed isomers in acetonitrile were significantly affected by the alkyl chain length. The results revealed that substituents of alkyl chain played an important role in the photoisomerization process of diarylethenes.
关键词： alkyl chain length,photochromism,pyrrole and thiophene units.,diarylethene
更新于2025-09-23 15:23:52
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Analysis of Network Structures in Thiol-Ene UV Curing System Using Reworkable Resins
摘要： An analysis of the network structures in thiol-ene UV curing resins was carried out using reworkable resins composed of di(meth)acrylate monomers having tertiary ester linkages. The effect of the functionality of the thiols, the functional ratio of the thiol and ene functions, their conversions and curing atmosphere on the chain lengths was discussed. A mixture of (meth)acrylates, thiol compounds, a photoradical initiator, and a photoacid generator was cured by irradiation at 365 nm. The cured samples were degraded by heating after irradiation at 254 nm. Size exclusion chromatography (SEC) and 1H NMR analyses of the degraded samples were carried out after the methylation. The crosslinking conditions strongly affected the network structures. The degraded samples have molecular weights between 250 and 2700. The molecular weights of the degraded resins increased with the functionality of the thiol compounds. The chain length dependence suggests that thiol compounds with a high functionality have a low reactivity due to steric hindrance. The chain lengths of the degraded networks were nearly proportional to the concentration of the (meth)acrylate monomers. The addition of reactive diluents enhanced the reactivity and increased the chain length.
关键词： thiol-ene reaction,UV curing,crosslinking,chain length,degradation,reworkability
更新于2025-09-23 15:22:29
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Effect of the alkyl chain length on the optoelectronic properties of organic dyes: theoretical approach
摘要： In recent years, investigating organic compounds for Dye Sensitized Solar Cells (DSSCs) applications has received particular attention for its interesting optoelectronics properties. In this article, we have conducted a theoretical study on a series of D–π–A molecules, which have carbazole as a donor (D) and cyanoacrylic acid as acceptor (A) linked by a conjugated bridge. Theoretical calculations were conducted using Density Functional Theory (DFT) and Time-Dependent-DFT to evaluate the substitution effect of linear chains and to elucidate the effects of alkyl chain length (R: H, CH3 to C6H13). We have studied the geometrical structures, the electronic and optical properties, the conduction band shift, as well as the charge transfer parameters: IP, EA, PEE, HEP, λ, LHE, Voc, ΔGinject and ΔGreg of the studied dyes. According to the results obtained, the substitution of hydrogen H (Dye 1) by the methyl group CH3 (Dye 2) has, on the one hand, a significant effect on the values of the energies HOMO and LUMO, and on the other hand, the absorption peak is redshifted and the contribution of the electronic transition (H → L) has been improved (664.17 nm and 70%, respectively). However, the substitution of CH3 (Dye 2) by the other alkyl groups CnH2n+1 (n = 2 to 6) (Dye 3 to Dye 7) has low effects. The best results are obtained by substitution with methyl CH3, and the increase in chain length, which will require additional computing time, has a low effect on the properties of the dyes studied.
关键词： DFT,Optoelectronic properties,Alkyl chain length,Dyes
更新于2025-09-23 15:21:01
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Correlated alkyl chain length to defect passivation efficacy in perovskite solar cells
摘要： We for the first time correlated the alkyl chain length of amine molecules to the defect passivation efficacy, either on surface or at grain boundaries of perovskite films. Blade-coated perovskite solar cells with long-chain amines passivation achieved an efficiency of 21.5%, accompanied by a small voltage loss of 0.35 V.
关键词： efficiency,defect passivation,blade-coating,alkyl chain length,perovskite solar cells
更新于2025-09-23 15:19:57
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Effects of alkylamine chain length on perovskite nanocrystals after washing and perovskite light-emitting diodes
摘要： Organic-inorganic hybrid lead halide perovskite nanocrystals (PeNCs) have great attention as a light source for perovskite light-emitting diodes (PeLEDs) owing to the superior optical properties. However, PeNCs typically use octylamine (OAm) as capping ligands which have insulating properties. Exploring a desirable short-alkylamine instead of OAm is required for the improvement of PeLEDs. Here, as a one of the strategies to solve this issue, the effects of alkylamine chain length for optical properties of PeNCs and PeLED characteristics are investigated. Pentylamine is an optimal short-alkylamine and precipitate luminescent PeNCs with high PLQY values of 90%. Importantly, pentylamine maintains a relatively high PLQY of 48% after spin-coating, due to the durability pentylamine has to ethyl acetate as a washing solvent. PeNCs capped with pentylamine also demonstrate an external quantum efficiency of over 1% with luminance of over 2000 cd/cm2, indicating that pentylamine has the potential to overcome the insulator properties of PeNC thin film.
关键词： optical properties,light-emitting diodes,perovskite nanocrystals,washing process,alkylamine chain length
更新于2025-09-11 14:15:04