Since their introduction, dye-sensitized solar cells (DSCs) have achieved huge success at a laboratory level. Recently, research is concentrated to visualize large DSC modules at the commercial platform. In that aspect, we have tested structurally simple porphyrin-based dye SK6 and anthracene-based dye CW10 for DSCs application under simulated 1 sun (AM 1.5G) and indoor light sources. These two dyes can be easily synthesized and yet are efficient with cell performances of ca. 5.42% and ca. 5.75% (without coadsorbent/additive) for SK6 and CW10, respectively, under AM 1.5G illumination. The power conversion efficiency (PCE) of SK6 reported in this work is the highest ever reported; this is achieved by optimizing the adsorption of SK6 on TiO photoanode using the most suitable solvent and immersion period. Cosensitization of SK6 with CW10 on TiO surface has boosted cell performance further and achieved PCE of ca. 6.31% under AM 1.5G illumination. Charge-transfer properties of individual and cosensitized devices at TiO/dye/electrolyte interface were examined via electrochemical impedance spectroscopy. To understand the cell performances under ambient light conditions, we soaked individual and cosensitized devices under T5 and light-emitting diode light sources in the range of 300-6000 lx. The PCE of ca. 22.91% under T5 light (6000 lx) with J = 0.883 mA cm, V = 0.646 V, and FF = 0.749 was noted for the cosensitized device, which equals a power output of 426 μW cm. These results reveal that DSCs made of structurally simple dyes performed efficiently under both 1 sun (AM 1.5G) and indoor light conditions, which is undoubtedly a significant achievement when it comes to a choice of commercial application.

A series of zinc porphyrin dyes YD22-YD28 were synthesized and used for dye-sensitized solar cells. Dyes YD26-YD28 consist of zinc porphyrin (ZnP) as core unit, arylamine (Am) as electron-donating group, and p-ethynylbenzoic acid (EBA) as an electron-withdrawing/-anchoring group. The dyes YD22-YD25 contain additional phenylethynylene group (PE) bridged between Am and ZnP units. The influence of the PE unit on molecular properties as well as photovoltaic performances were investigated via photophysical and electrochemical studies and density functional calculations. With the insertion of PE unit, the dyes YD22-YD25 possess better light-harvesting properties in terms of significantly red-shifted Q-band absorption. The conversion efficiencies for dyes YD22-YD25 are better than those of dyes YD26-YD28 owing to larger J(SC) output. Natural transition orbitals and Mulliken charge analysis were used to analyze the electron injection efficiency for porphyrin dyes upon time-dependent DFT calculations. The results indicated that insertion of additional PE unit is beneficial to higher J(SC) by means of improved light-harvesting property due to broadened and red-shifted absorption.

Conventional epoxy resins can meet the requirement for engineering applications in which high glass transition and thermal stability are essential, but they show no degradability or recyclability. Vitrimers, with covalent adaptable networks, provide reprocessability and degradability. However, the thermally activated bond-exchange reactions prevent the composites from being thermal-mechanically stable at high temperatures. Therefore, developing epoxy/carbon fiber composites with thermal stability and degradability is attractive for industrial applications and environmental sustainability. In this work, we report the degradability of two thermal-mechanically stable epoxy networks derived from self-curing of two eugenol-based epoxy resins: bis­(2-methoxy-4-(oxiran-2-ylmethyl)­phenyl) succinate (II) and tris­(2-methoxy-4-(oxiran-2-ylmethyl)­phenyl)­benzene-1,3,5-tricarboxylate (III). Degradation can be proceeded through aminolysis of aliphatic esters in the networks at a mild condition. The exact structures of degraded products were precisely analyzed by 1H NMR spectra. An epoxy/carbon fiber composite based on III/carbon fiber was prepared. After degrading the epoxy network, the carbon fiber was recycled. Scanning electron microscopy (SEM) pictures show that the recycled carbon fiber is intact and looks the same as the virgin one. Furthermore, we modified the degraded product of epoxy networks for reapplication. One of the degraded products, oligo­(1-oxy-3-(3-methoxy-4-phenylene)­propan-2-ol) (IIc), was further reacted with methacrylic anhydride to obtain oligo­(1-oxy-3-(3-methoxy-4-phenylene)­propan-2-methacrylate) (IId). IId was further thermally cross-linked to a thermoset (IIe) with a T g value of 170 °C. The successful degradation and reapplication of thermal-mechanically stable epoxy networks and the recycling of carbon fibers are well demonstrated.

We prepared two phenylacetate end-capping oligoesters from recycled bisphenol A (RBPA), which is obtained from a phase-transfer agent-assisted basic degradation of waste polycarbonate (WPC). The two oligoesters were successfully applied as epoxy-curing agents. The curing of oligoesters with epoxy is based on the chemistry of a 4-dimethylaminopyridine (DMAP)-catalyzed model reaction of phenyl benzoate and glycidyl phenyl ether. Mechanical and thermal properties of oligoesters/epoxy-cured thermosets were investigated and discussed. Glass transition temperatures (T g), the coefficient of thermal expansions (CTE), thermal decomposition temperatures (T d5%), and tensile strengths of four thermosets are, respectively, in the ranges of 140 to 180 °C, 37 to 72 ppm/°C, 396 to 431 °C, and 49 to 73 MPa. We also prepared carbon fiber composites (CFRPs) by using oligoester/epoxy resin, which could be effectively degraded to phenoxy resin using a catalyst-free aminolysis technique, and undamaged carbon fibers could be recycled without sacrificing mechanical strength or chemical composition. Processes such as recycling of WPC into bisphenol A-based oligoesters as epoxy-curing agents and degrading the epoxy thermosets and CFRPs into useful chemicals have been achieved.

In this work, we have synthesized a novel porphyrin dye named SK7, which contains two N,N-diarylamino moieties at two β-positions as electron-donating units and one carboxy phenylethynyl moiety at the meso-position as an electron-withdrawing, anchoring group. This novel dye was tested for the application in dye-sensitized solar cells. The light-harvesting behavior of SK7 and YD2 was investigated using UV–vis absorption and density functional calculation. The electron transport properties at the TiO2/dye/electrolyte interface for SK7- and YD2-based devices were evaluated by electrochemical impedance spectroscopy. X-ray crystallographic characterization was conducted to understand the influence of two N,N-diarylamino units at two β-positions. The power conversion efficiencies of ca. 6.54% under 1 sun illumination (AM 1.5G) and ca. 19.72% under a T5 light source were noted for the SK7 dye. The performance of SK7 is comparable to that of dye YD2, which contains only one N,N-diarylamino moiety at the meso-position (ca. 7.78 and 20.00% under 1 sun and T5 light, respectively).

The retention time of resistor type memory devices could be tuned by the linkage groups between porphyrin moiety and DSDA on the PIs. Moreover, the metal zinc also plays an important role in further tuning the memory behavior.

We report a robust, 100% atom-efficiency strategy for preparing waste polycarbonate (WPC)-derived epoxy resin. To demonstrate the preparation process, we perform a pyridine-catalyzed model reaction between diphenyl carbonate (DPC) and diglycidyl ether of bisphenol A (DGEBA) in a molar ratio of 1:2. After epoxy-equivalent titration and two-dimensional nuclear magnetic resonance (2D-NMR) analysis, we confirm that the product is bis­(1-(4-(2-(4-(oxiran-2-ylmethoxy)­phenyl)­propan-2-yl)­phenoxy)-3-phenoxypropan-2-yl) carbonate (DPC-EP2). Based on the model reaction, three WPC-based epoxy resins (WPC-EPX, X = 2, 3, and 4) were prepared by the reaction of WPC with DGEBA in a molar ratio of 1:2, 1:3, and 1:4 in the presence of pyridine. The WPC-EPX epoxy resins were cured with WPC, phenol novolac (PN), diamino diphenylmethane (DDM), and dicyandiamide (DICY). The mechanical and thermal properties of the thermosets were discussed. We also prepared epoxy/carbon fiber composites and investigated the degradation of epoxy thermosets and the recycling of the carbon fiber. When the WPC-EP2 epoxy resin was cured with WPC, it can be successfully degraded to a phenoxy resin and 1,3-dihyexylurea through a catalyst-free aminolysis process. Undamaged carbon fibers have been recycled, according to the scanning electron microscopy–energy-dispersive X-ray spectroscopy (SEM–EDS) and tensile stress–strain data. The transformation of WPC to WPC-EPX, the aminolysis of WPC-EP2/WPC to a phenoxy resin and 1,3-dihexylurea, and the recycling of carbon fiber in the composite have been successfully demonstrated. Therefore, we believe that this work contributes greatly to the field of “sustainable approaches in waste utilization.”

An intrinsic flame-retardant moiety, 9,10-dihydro-9oxa-10-phosphaphenanthrene-10-oxide (DOPO), is incorporated into oligo(2,6-dimethyl-1,4-phenylene ether) (OPE), and four phosphorus-containing telechelic OPE resins are synthesized. The first is synthesized with a para phenyl methacrylate end group (OPE-PM); the second is synthesized with para and meta phenyl methacrylate end groups (OPE-OPM); the third is synthesized with a para vinyl benzyl ether end group (OPE-VBE); and the fourth is synthesized with para and meta vinyl benzyl ether end groups (OPE-OVBE). All the self-cured samples showed good flexibility, high temperature (T g = 216 to 250 °C, T d5% > 400 °C), and water resistance (0.25%). The self-cured OPE-OPM and OPE-OVBE show outstanding low dielectric values of 2.63 and 2.65 and impressive low dissipation factors of 0.0035−0.0047 at 10 GHz, respectively. The results indicate that a further crosslinking behavior in the chain end can enhance the rigidity and further enhance the dielectric properties. Most importantly, all phosphinated thermosets show excellent burning resistance, and both UL-94 VTM and microscale combustion calorimetry experiments were conducted to explain the flame-retardant behavior. We believe that this work will contribute greatly to the research related to polymeric substrate materials for 5G technology.