- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Influence of the intramolecular donor-acceptor distance on the performance of double-cable polymers
摘要： A series of double-cable polymers PFT-C4-PDI, PFT-C6-PDI and PFT-C8-PDI, composed of the poly(fluorene-alt-thiophene) (PFT) backbone, the perylene diimide (PDI) pendants and the length-various (four-, six- and eight-carbon) covalent alkoxy linkers, were presented. The backbone polymer chain created the hole-transporting channel and the inner-chain aggregation of PDI units created the electron-transporting channel, but the aggregation became weaker along with the longer linker, as proven by the UV-Vis absorption and fluorescence quenching. The polymers were non-conducting, but functioned as efficient compatibilizers. The doping of the polymers induced the formation of the bi-continuous networks inside P3HT:PCBM blends, facilitated photo-generated exciton dissociation and charge transporting. PFT-C4-PDI more efficiently increased the absorption coefficient and the charge-carrier mobility of the P3HT:PCBM film. The power conversation efficiency (PCE) of the P3HT:PCBM bulk-heterojunction solar cells with 3 wt% PFT-C4-PDI, PFT-C6-PDI and PFT-C8-PDI doping were improved by 16.9%, 9.2% and 8.0%, respectively, relative to the non-doped reference device.
关键词： Structure-property relationships,Energy transfer,Double-cable polymer,Polymer solar cells,Bi-continuous networks
更新于2025-09-23 15:23:52
-
Asymmetric Diarylethenes with Oxidized 2-Alkylbenzothiophen-3-yl Units: Chemistry, Fluorescence, and Photoswitching
摘要： Reversibly photoswitchable diarylethenes (DAEs) with fluorescent closed forms are applied in biology- and material science-related super-resolution microscopy. Yet, their full photoswitchable capacities remain unrevealed and unexplored. Due to limitations in synthesis, only 1,2-[bis-(2-ethyl-1-benzothiophene-1,1-dioxide-3-yl)]perfluorocyclopentenes with two identical or very similar aryl groups attached to C-6 and C-6′ have been prepared so far. DAEs with increased Stokes shifts related to asymmetric structures and the presence of 'push–pull' substituents are introduced in the present study, and their switching power is studied. The new 'simplified' asymmetric DAEs possess higher cycloreversion quantum yields, but lower emission efficiencies than their known analogs with extended π-conjugation paths. Fatigue resistance in organic (acetonitrile and methanol) and aqueous solvents is studied, and the performance in reversible saturable optical fluorescence transition (RESOLFT) microscopy is evaluated. The push–pull structures show an outstanding increase in fatigue resistance, compared with a reference (H/H) diarylethene. Fatigue resistances on the order of thousands of cycles have been observed in acetonitrile solutions without exclusion of air oxygen. The structure–property relationships and facile preparation procedures enable rational design of DAEs applicable as photoswitchable fluorescent probes. A new setup and methodology for measuring switching performance of fluorescent DAEs are introduced.
关键词： photoluminescence,photonics,photochemistry,structure–property relationships
更新于2025-09-23 15:23:52
-
Materials containing benzocyclobutene units with low dielectric constant and good thermostability prepared from star-shaped molecules
摘要： With the development of ultralarge-scale integrated circuits, polymers with low dielectric constant and high thermal stability have aroused great interest. We prepared two novel bridged siloxane-based benzocyclobutene (BCB) star-shaped monomers, tetrakis[dimethyl siloxy-4-(10,10-dimethyl-10-ethyl silicon)-benzocyclobutene] (TDSDES-BCB) and tetrakis(hexamethyl siloxane vinyl-benzocyclobutene) (THSV-BCB), and the corresponding resins were obtained by curing. The structures of TDSDES-BCB and THSV-BCB were confirmed by 1H-NMR, 13C-NMR, and 29Si-NMR spectra and time-of-flight mass spectrometry analysis. The curing behavior of these monomers was investigated by Fourier transform infrared spectroscopy and differential scanning calorimetry. The dielectric constant of cured TDSDES-BCB is only 2.43 at 10 MHz (that of THSV-BCB is 2.46). In addition, these resins display high thermal stability: the 5 wt % weight loss temperature of cured TDSDES-BCB is about 467 °C (454 °C for THSV-BCB resin). The excellent low dielectric property is attributable to the free volume created by the star-shaped structure and crosslinked network structure of BCB after curing.
关键词： thermosets,structure–property relationships,resins,dielectric properties,thermal properties
更新于2025-09-23 15:22:29
-
Acceptora??donora??acceptor type molecules for high performance organic photovoltaics a?? chemistry and mechanism
摘要： The study of organic photovoltaics (OPVs) has made great progress in the past decade, mainly attributed to the invention of new active layer materials. Among various types of active layer materials, molecules with A–D–A (acceptor–donor–acceptor) architecture have demonstrated much great success in recent years. Thus, in this review, we will focus on A–D–A molecules used in OPVs from the viewpoint of chemists. Notably, the chemical structure–property relationships of A–D–A molecules will be highlighted and the underlying reasons for their outstanding performance will be discussed. The device stability correlated to A–D–A molecules will also be commented on. Finally, an outlook and challenges for future OPV molecule design and device fabrication to achieve higher performance will be presented.
关键词： chemical structure–property relationships,device stability,organic photovoltaics,acceptor–donor–acceptor,molecule design
更新于2025-09-23 15:21:01
-
Benzodithiophenedione-based polymers: recent advances in organic photovoltaics
摘要： Over the past 20 years, significant progress has been made in organic photovoltaics (OPVs) due to its advantages of being cost-effective, being lightweight, and having flexible manufacturability. The optical-active layer of OPVs consists of a p-type polymer as the donor and an n-type small molecule as the acceptor. An efficient design strategy of a polymer donor is based on an alternating electron-donating unit (D) and an electron-accepting unit (A). Among numerous electron-accepting units, an emerging annelated thiophene of benzodithiophenedione (BDD) has exhibited a distinguished photovoltaic performance because of its planar molecular structure, low-lying highest occupied molecular orbit (HOMO) level and good self-assembly property. In this review article, we summarize the most recent developments in BDD-based photovoltaic materials. Special attention is paid to the chemical structure-property relationships, such as the absorption, bandgap, energy levels, mobilities, and photovoltaic performances. The empirical regularities and perspectives on the future development of BDD-based photovoltaic materials are included.
关键词： chemical structure-property relationships,benzodithiophenedione,photovoltaic performance,polymer donors,organic photovoltaics
更新于2025-09-16 10:30:52
-
Improving LED efficiency with the new polymorph β‐Ca1‐xSrxAlSiN3:Eu2+
摘要： Innovative materials for phosphor converted white light-emitting diodes (pc-LEDs) are much sought after due to the huge potential of the LED technology to reduce energy consumption worldwide. One of the main levers for further improvements are the conversion phosphors. The system Ca1?xSrxAlSiN3:Eu2+ currently provides one of the most important red emitting phosphors for pc-LEDs. We report the discovery of the new polymorph β-Ca1?xSrxAlSiN3:Eu2+ which allows significant improvements to LED efficacies. It crystallizes in the orthorhombic space group Pbcn with lattice parameters a = 982.43(10) pm, b = 575.2(1) pm, and c = 516.12(5) pm. Compared to α-Ca1-xSrxAlSiN3:Eu2+, its emission shows significantly reduced spectral full-width at half maximum (FWHM). With that, we demonstrated 3% efficacy increase for white light-emitting pc-LEDs. The new polymorph can easily be industrialised, because the synthesis works on the same equipment as α-Ca1?xSrxAlSiN3:Eu2+.
关键词： luminescence,polymorphism,structure-property relationships,nitridoaluminosilicate
更新于2025-09-11 14:15:04
-
Thermally resistant photocrosslinked damping poly(phenylene oxide)-fluorosilicone rubber films with broad and high effective damping temperatures
摘要： The development of an energy-ef?cient strategy to prepare thermally resistant damping materials with high damping capacities (tan δ values) and broad effective damping temperature ranges (ΔTs) at high temperatures (>150 (cid:1)C) is still an interesting challenge. In this study, a graft copolymer (PSi-g-APPO) was synthesized through the reaction between hydrogen-terminated ?uorosilicone and allyl poly(phenylene oxide) (APPO), and a unique kind of photocrosslinkable ?lm (coded as GFA) consisting of FSR, APPO and PSi-g-APPO was prepared. The resultant GFA has high thermal resistance, wide ΔT, and high tan δ. When the weight ratio of APPO to FSR to PSi-g-APPO was 81:9:10, the obtained ?lm exhibited a broad ΔT of 64 (cid:1)C and a high tan δ (≤1.01) from 157 to 221 (cid:1)C; this was the best comprehensive performance among the GFA systems. The mechanism behind the excellent integrated performance of GFA was studied and was proven to be due to the unique structure of the heterogeneous GFA system.
关键词： thermal properties,crosslinking,structure–property relationships,blends,?lms
更新于2025-09-04 15:30:14