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Under the guidance of a symmetry-breaking and π-bridge-extending strategy, three asymmetric and symmetric non-fullerene acceptors (L1, L2, and L3) with DA′D core units and two 2-(5,6-difluoro-3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile electron-withdrawing units (A) have been designed and synthesized via changing the alkoxy-substituted thiophene bridge unit. The asymmetric A–DA′D–π-A-type non-fullerene acceptor (NFA) L2 displays much improved solubility and a slightly larger molar absorption coefficient than its symmetric counterparts (L1 and L3). In addition, blend film based on the asymmetric NFA L2 shows suitable nanoscale phase morphology and much higher and more balanced hole and electron mobilities. Hence, compared with L1- and L3-based organic solar cells (OSCs), optimal L2-based devices can deliver a high power-conversion efficiency (PCE) of 14.06% with simultaneously enhanced current density and fill factor values. Our study indicates that a combined symmetry-breaking and π-bridge-extending strategy is powerful for the design of high-performance NFAs.

With a focus on converting waste to energy, this study integrated the macromolecular reaction ability of Al-SBA-15 and the shape selectivity of HZSM-5 for the production of renewable aromatic hydrocarbons. Results demonstrated that the catalytic pyrolysis of lignin with both Al-SBA-15 and HZSM-5 was able to improve the mono-aromatic hydrocarbons (MAHs) production while inhibiting the formation of undesirable poly-aromatic hydrocarbons (PAHs), thus controlling the MAHs and PAHs content in the bio-oil. At optimal operation conditions (pyrolysis temperature: 550 °C, Al-SBA-15/HZSM-5 ratio: 1:3), the MAHs content was 42.57% higher than that catalyzed by HZSM-5 only (28.30%). The PAHs content was only 27.13%. Typical MAHs (benzene, toluene and xylene, denoted as BTX) and PAHs selectivities were determined as 55.91% and 38.92%, respectively. Thermogravimetry-differential thermogravimetric (TG-DTG) analysis indicated that the used HZSM-5 was principally composed of graphite-like coke and a negligible content of fibrous-like coke. The coke content was observed as 5.65% compared to 10.52% in the HZSM-5 only. Furthermore, the efficient synergistic effect of Al-SBA-15 and HZSM-5 resulted in the deep conversion and directional reforming of the lignin pyrolysis vapors. This study can promote the high-grade utilization of lignin through the application of feasible fixed-bed catalytic pyrolysis technology.

The steam reforming of bio-oil-derived acetic acid over the developed Ni/CeO2-ZnO nanoparticle catalysts for hydrogen production was studied. The correlations of CeO2 to ZnO mass ratio (CZMR) and nickel loading with the properties and performances of Ni/CeO2-ZnO catalysts were explored. The H2, CO, and potential H2 yields followed a Gaussian normal distribution with increasing the CZMR. An exponential function equation was established to correlate the H2, CO, and potential H2 yields with Ni loading. As the CZMR increased from 0 to 1/3, the H2 yield increased from 57.8 to 69.4%, with a growth rate of 20.1%. Further, on increasing the CZMR from 1/3 to 3, the H2 yield decreased by 37.6%. The CO yield showed a similar trend for the H2 yield on increasing the CZMR, which first increased to a peak value, then started to decrease rapidly and finally stabilized. The yield of H2 increased significantly from 20.6 to 73.5%, with the increase of nickel loading from 0 to 15%. Further, on increasing the nickel loading from 15 to 25%, the H2 yield increased by only 5.8%. With the CZMR of 1/3 and the nickel loading of 15%, the selectivities of H2 and CO were as high as 91.6 and 42.3%, respectively.

Wood vinegar is a by-product with complex components in the wood carbonization process. In this paper, catalytic reforming technology was employed for reutilize of wood vinegar with a Ni/CoAl2O4 catalyst. In order to clarify its trigger mechanism, instantaneous gases yield and components evolution were investigated at initial stage. Results showed that nearly all components in wood vinegar could efficiently participate in catalytic reforming reaction. The initiation of the catalytic reforming reaction was attributed to the cleavage of the O–H bonds caused by the adsorption of O atoms to oxygen vacancies on the surface of the catalyst. The C–H bonds could also be broken under the action of oxygen vacancies to produce hydrogen; however, the metallic carbide accompanying was the primary cause of catalyst deactivation.

Long noncoding ribonucleic acids (lncRNAs) are critical regulators in various biological processes. In the present study, we aimed to explore whether miR140-3p was involved in the underlying molecular mechanisms of small nucleolar RNA host gene 1 (SNHG1) in myocardial ischemia/reperfusion (I/R) injury. A mouse model of I/R injury and hypoxia-reoxygenation (H/R)-stimulated human umbilical vein endothelial cells (HUVECs) was used in this study. Cell proliferation was detected by MTT. The mRNA and protein levels of vascular endothelial growth factor (VEGF), VE-cadherin, and MMP2 were detected by RT-PCR and western blot, respectively. The angiogenesis was assessed by tube formation assay. Cell migration was assessed using wound-healing assay. Results showed that SNHG1 expression was increased in the cardiac microvasculature of a mouse model of I/R injury and in H/R-stimulated HUVECs. H/R stimulation significantly reduced cell proliferation, tube formation, and cell migration, but increased expression of VEGF, VE-cadherin, and MMP2. SNHG1 upregulation under H/R increased HUVECs proliferation, tube formation, and cell migration, and upregulated expression of VEGF, VE-cadherin, and MMP2, compared with the H/R group. SNHG1 knockdown exhibited the opposite effect. SNHG1 functioned as a competing endogenous RNA (ceRNA) of miR-140-3p. HIF-1α was identified as a target of miR-140-3p. SNHG1 upregulation enhanced cell proliferation, tube formation, and expression of VEGF, VE-cadherin, and MMP2 through HIF-1α/VEGF signaling. This process could be offset by miR-140-3p mimic or VEGF inhibitor. Our results reveal a novel protective function of SNHG1 that furthers understanding of cardiac I/R injury and provides experimental evidence for future therapy.

The first example of a two-state (neutral and reduced), stable electron-accepting material and its radical anion is presented. FV-PDI, generated from cyclocarbonylation and then a carbonyl coupling reaction, shows a largely degenerate LUMO of -4.38 eV based on the delocalization of π-electrons across the whole molecular skeleton through a fulvalene bridge. The stability and electron affinity allow spontaneous electron transfer to afford a stable radical anion. Spectroscopic characterization and structural elucidation showed that the radical anion [FV-PDI].- has remarkable stability and near-infrared absorptions extending to 1200 nm. Single-crystal X-ray diffraction analyses revealed significant changes in the molecular shape and packing arrangement of the formed radical anion. The central C-C bond linking the two PDI halves is lengthened from approximately 1.33 to 1.43 A, and the alternating arrangement of positively and negatively charged units favor the stable charge-transfer complex.

In order to study the reaction mechanism of steam reforming of bio-oil, acetic acid was selected as the model compound and Ni/Al2O3 as the catalyst to carry out a series of experiments. Through the comparative analysis of instantaneous gases productions, composition of liquid phase products and carbon deposition, we can infer the reaction mechanism of acetic acid catalytic reforming and carbon deposition process. It is found that dehydrogenation reaction, water-gas shift reaction and methane (CHx) reforming reaction are the main source of H2, while [CHx] catalytic cracking reaction and CO disproportionation reaction lead to carbon deposition, furthermore carbon-steam gasification reaction can consume carbon deposition to a certain extent. Acetone is an important intermediate for carbon deposition, leading to rapid deactivation of the catalyst. By characterizing the catalyst after the reforming reaction, we consider that the formation of carbon deposition mainly includes two stages: the coating of active sites and the growth of fibrous carbon deposition. The carbon deposition on the surface of used-catalyst is 0.86%, which is mainly composed of the accumulated [C C] and [C C] bonds.

The hybridization of different acceptors remains a fertile ground awaiting exploration, to fully promote the properties of both components. The concept of this work is to exploit a new form of fuller-rylene hybrids as promising acceptors by integrating planar rylene dye and spherical fullerene for boosting the power conversion efficiency. The synthesis of the fuller-rylenes via a straightforward synthetic strategy by one-pot Pd-catalyzed cyclization can be scaled-up. Specifically, our strategy allows the supplements and enhancement of absorption in the visible region, much wider structural and electronic variations by installing R

In order to explore the reforming process of biomass pyrolysis oil in depth, the catalytic steam reforming (SR) of crude bio-oil (BIO) derived from rapid pyrolysis of rice husk and its derivatives for hydrogen production was studied by means of a bench-scale fixed-bed unit combined with the FTIR/TCD technique. The physico-chemical properties and compositions of BIO were determined. Acetic acid (HOAc), ethylene glycol (EG), acetone (ACE) and phenol (PHE) were selected as four representative bio-oil derivatives. Evolution characteristics of H2, CO, CO2 and CH4 during SR of HOAc, EG, ACE, PHE and BIO were revealed and compared. The hydrogen yield increased sharply with reaction time to the peak values of 24.7%, 32.3%, 16.4%, 25.6% and 24.9%, corresponding to HOAc, EG, ACE, PHE and BIO, respectively. After that, the yield of hydrogen exhibited a downward trend, suggesting that the catalyst ability for selective hydrogen production gradually decreased. The H2 yield from EG was the highest, followed by PHE, HOAc, BIO and ACE. The order of CO yields from large to small was EG > HOAc > ACE > BIO ≈ PHE. The percentages of coke deposited on catalyst were arranged in descending order as HOAc > BIO > ACE > PHE > EG. This study could provide more detailed information on the catalytic reforming mechanism of bio-oil on the one hand, and also point out the direction for the improvement of the catalysts, which play a role in ensuring the high yield of H2 while converting CO to H2 through the water gas shift reaction.

There are huge demands for the development of green, environmentally friendly, and easily prepared cationic adsorbents for treatment of chromium-contaminated water. In this research, we demonstrate the fabrication of a novel polyvinylamine-grafted polypropylene membrane (PPM-PVAm) for Cr(VI) adsorption. Based on a rapid two-step method, polypropylene membrane (PPM) was grafted with high biomedical safety N-vinylformamide (NVF), and then amino groups were generated via hydrolysis of the poly(N-vinylformamide) (PNVF) and these amino groups could be protonated under acidic condition as Cr(VI) adsorbing sites. The effects of both the PNVF grafting rate and its degree of hydrolysis on the adsorption performance of PPM-PVAm were investigated. The membrane with a PNVF grafting rate around 55% (wt) and a degree of hydrolysis around 70–80% exhibits the best performance for Cr(VI) adsorption under the optimal conditions, i.e. pH 2 at about 40 °C. The adsorption of Cr(VI) on PPM-PVAm matches the Langmuir model, showing a maximum Cr(VI) adsorption capacity of 208.3 mg per gram dry membrane. PPM-PVAm could be deprotonated under alkaline condition so the adsorbed Cr(VI) could be easily removed by NaOH/NaCl aqueous solution. The membrane shows excellent recycling performance, and 90.6% of the adsorption capability remains even after 10 cycles of adsorption-desorption test. Combining the unique performance and eco-friendly process in the fabrication of the membrane, PPM-PVAm shows great potential in adsorptive removal of Cr(VI) from water.

Two novel highly fluorescent hydroxyl-substituted perylene diimides derivatives, N,N-dicyclohexyl-1-hydroxyperylenediimide (1) 2,9-dicyclohexyl-5,5-dimethyl-12-hydroxy-5,6-dihydropyreno[2,1,10-def:7,8,9-d′e′f′]diisoquinoline-6-oxa-1,3,8,10(2H,9H)-tetraone (2) were designed and efficiently synthesized through a single aromatic nucleophilic displacement reaction. The physical properties of the as-prepared compounds had been fully studied. Both receptors have shown no affinity for other anions, such as Cl−, Br−, I−, SO4−, PF6−, H2PO4−, BF4−, AcO−, ClO4− (as salt of tetra-n-butylammonia) and ammonium hydroxide. Interestingly, they can be served as colorimetric and fluorescent chemodosimeter for fluoride ion using hydroxyl as binding sites, which was the first report of hydroxyl-modified PDIs based photodetector of fluoride ion. Upon addition of F− anion to compound 2 solution, dramatic color change and fluorescence quenching were observed. Furthermore, the red-shifted maximum absorption wavelength reached 207 nm to the far-red region, which was the maximal spectrum bathochromic-shift of PDIs used in fluoride detection. In addition, the two fluoride sensor can be used under illumination from a laboratory hand-held UV lamp. These results demonstrated that using facile synthetic routes to constructing PDIs molecules with hydroxyl moiety was a useful strategy for designing high performance fluoride recognization.

Three regio-regular benzodithiophene-based donor-donor (D-D)-type polymers (PBDTT, PBDTT1Cl, and PBDTT2Cl) are designed, synthesized, and used as donor materials in organic solar cells (OSCs). Because of the weak intramolecular charge transfer effect, these polymers exhibit large optical bandgaps (>2.0 eV). Among these three polymers, PBDTT1Cl exhibits more ordered and closer molecular stacking, and its devices demonstrate higher and more balanced charge mobilities and a longer charge separated (CS) state lifetime. As a result of these comprehensive benefits, PBDTT1Cl-based OSCs give a very impressive power conversion efficiency (PCE) of 17.10% with a low nonradiative energy loss (0.19 eV). Moreover, PBDTT1Cl also possesses a low figure-of-merit (FOM) value and good universality to match with different acceptors. Our work provides a simply and efficient strategy to design low-cost high-performance polymer donor materials. This article is protected by copyright. All rights reserved.

A novel PDI-based electron acceptor, namely dicyanopentafulvene-fused PDI (3) is presented via Knoevenagel condensation with malononitrile in a simple and efficient way from the key intermediate cyclopentadienone-annulated PDI (2). The resulting degenerated LUMO level of approximately −4.29 eV is based on the fusion of multiple cyano groups and delocalization of π-electrons across the molecular skeleton. A stable radical anion is thus produced between 3 and cobaltocene (CoCp2) in 1:1 ratio, which was unambiguously confirmed by spectroscopic characterization and structural elucidation. The broad NIR band from 900 nm to 1300 nm is characteristic of delocalized unpaired electron in CT complex 3·CoCp2. Single crystal X-ray diffraction analyses revealed distinction in the molecular shape and packing arrangement before and after forming radical anion. Remarkably, the presence of intensive π···π interactions endow them good electron transporting characteristics, signifying the prospects in the organic electronic or spintronic devices.

Impacts of pyrolysis temperature of biochar on lead adsorption from aqueous solution and related mechanisms were investigated in this work. Biochars derived from cotton stalk were prepared under temperature from 250 to 650 ℃. The physicochemical properties and the Pb2+ adsorption capacity (Qe) of biochar were characterized. The results revealed that Qe was positively correlated (p

Cost-effective and green separation of aromatic pollutant from waste water is of great importance in sustainable chemistry and engineering but under challenges of high energy consumption and unsatisfactory separation efficiency. Herein, induced by the electrostatic interactions, lignosulfonate (LS) based superparamagnetic composite LS@γ-Fe2O3 was developed without any surface modification and activation process. The LS@γ-Fe2O3 magnetic composites exhibited meaningful amphiphilicity and then were applied as efficient material for the separation of toluene/water system through the combination of gravity filtration and magnetic demulsification methods. The results demonstrated that the composites exhibited an excellent separation rate (over 99.05 %) towards toluene/water with gravity filtration method. For the water with low toluene content (

Porphyrin-based molecules have been widely used in dye-sensitized solar cells and bulk-heterojunction solar cells, but their application in field-effect transistors (FETs) is limited. In this work, two conjugated polymers based on diketopyrrolopyrrole and porphyrin were developed for FETs. The polymers exhibit extra-low band gap with aligned energy levels close to -4.0 eV and -5.0 eV because of the strong electron-donating and withdrawing ability of aromatic units. With additionally high crystalline properties, ambipolar charge carrier transport with a hole mobility of 0.1 cm2 V-1 s-1 in FETs were achieved based on these polymers, which also represents the highest performance based on porphyrin-polymer FETs.

A star-shaped electron acceptor based on porphyrin as a core and perylene bisimide as end groups was constructed for application in non-fullerene organic solar cells. The new conjugated molecule exhibits aligned energy levels, good electron mobility, and complementary absorption with a donor polymer. These advantages facilitate a high power conversion efficiency of 7.4 % in non-fullerene solar cells, which represents the highest photovoltaic performance based on porphyrin derivatives as the acceptor.

We design and synthesize four pyran-embedded perylene diimide (PDI) compounds through a straightforward methodology. UV-driven photocatalytic water splitting using the compounds as photocatalysts demonstrates that the highest photocatalytic H2 evolution rate under UV light is 0.90 mmol g−1 h−1, which paves the way towards organic photoresponsive materials.

A series of halogenated conjugated molecules, containing F, Cl, Br and I, were easily prepared via Knoevenagel condensation and applied in field-effect transistors and organic solar cells. Halogenated conjugated materials were found to possess deep frontier energy levels and high crystallinity compared to their non-halogenated analogues, which is due to the strong electronegativity and heavy atom effect of halogens. As a result, halogenated semiconductors provide high electron mobilities up to 1.3 cm2 V−1 s−1 in transistors and high efficiencies over 9% in non-fullerene solar cells.

In this work, we present a new strategy to use fused and twisted conjugated backbones to construct conjugated small molecules and polymers as electron acceptors for non-fullerene solar cells. The new conjugated materials containing binary perylene bisimide (PBI) units linked with coplanar thieno[3,2-b]thiophene (as trans-PBI) or twisted thieno[2,3-b]thiophene (as cis-PBI) and the corresponding conjugated polymer cis-polyPBI were developed. A fused conjugated backbone ensures good charge transport, in which the twisted polymer cis-polyPBI was found to show the highest electron mobility of 1.2 × 10−2 cm2 V−1 s−1 in field-effect transistors. Meanwhile, a twisted conjugated backbone effectively prevents the aggregation and crystallization of PBI units, resulting in isotropic charge transport and finely tuned micro-phase separation in bulk-heterojunction thin films. The high electron mobility and isotropic crystallinity make the fused and twisted electron acceptors achieve high power conversion efficiencies above 6% in non-fullerene solar cells, while the coplanar molecule trans-PBI as the electron acceptor shows a very low efficiency of 0.13%.

Perylene bisimide (PBI) unit has been widely used to design conjugated materials, which can be used as electron acceptor in organic solar cells due to its strong electron-deficient ability. In this work, a conjugated polymer based on PBI dimer as monomer was designed, synthesized, and compared to the conjugated polymer containing single PBI as repeating units. The two conjugated polymers were found to have similar molecular weight, absorption spectra and energy levels. Density functional theory calculation revealed that the PBI dimer-based polymer exhibited highly twisted conjugated backbone due to the large dihedral angle between the two PBI units. The PBI-based polymers as electron acceptor were applied into polymer-polymer solar cells, in which PBI dimer-based polymer solar cells were found to show a high short circuit current density (J sc = 11.2 mA∙cm−2 and a high power conversion efficiency (PCE) of 4.5%. In comparison, the solar cells based on PBI-based polymer acceptor only provided a J sc of 7.2 mA∙cm−2 and PCE of 2.5%. The significantly enhanced PCE in PBI dimer-based solar cells was attributed to the mixed phase in blended thin films, as revealed by atom force microscopy. This study demonstrates that PBI dimer can be used to design polymer acceptors for high performance polymerpolymer solar cells.

In this work, a new asymmetrically five-membered O-heterocyclic annulated perylene diimide (O-PDI) has been synthesized. The compounds O-PDI and asymmetrically five-membered S-heterocyclic annulated perylene diimide (S-PDI) self-assembled into nanoneedle and nanosheet, respectively. Photophysical, electrochemical and thermal properties were investigated by UV–vis absorption, fluorescence, cyclic voltammetric, thermogravimetric and differential scanning calorimetry techniques. Optical, fluorescence, scanning and transmission electron microscopies were employed in the molecular self-assembly studies. Due to significant electronic coupling between their heteroatom/heterocycles and perylene diimide (PDI) cores, the intermolecular π-π actions are neglectable, providing high luminescence efficiency. At the same time, the space between perylene chromophores is still very short (3.3 A for O-PDI and 3.23 A for S-PDI), which is favorable for the hopping transportation of charge carrier from one molecule to a neighboring one. These compounds could be candidate materials for acquiring well defined organic nanostructures with both excellent charge-transporting and good light-emitting capabilities.

In this work, a new star-shaped electron acceptor based on porphyrin as core, rhodanine and benzothiadiazole as end groups, was developed for non-fullerene solar cells. The molecule shows three distinct absorption regions due to the Soret and Q-bands of the porphyrin and the intramolecular charge transfer in the molecule. This molecule as electron acceptor was applied into non-fullerene solar cells by using a diketopyrrolopyrrole-based conjugated polymer as electron donor. An initial PCE of 1.9% was achieved with a broad photo-response from 300–850 nm. The results demonstrate that porphyrin can be used to design near-infrared electron acceptors for organic solar cells.

Corn stover can be converted into a high market value product via catalytic fast pyrolysis. Specifically, through thermochemical conversion, corn stover can be converted into biocrude oil with a high content of unstable phenols, most notably active phenols, which can readily react with aldehydes to form phenolic resins. Therefore, the higher the content of active phenols, the greater the economic value of biocrude oil. This is due to the potential for active phenols to serve as value-added compounds in the form of phenolic resins. Catalysts can be incorporated to improve the reaction rate and product quality during fast pyrolysis. In this study, the effects of three solid catalysts, dolomite, red mud and HZSM-5(25), on the production of active phenols were investigated. The Folin-ciocalteu (FC) method and gas chromatography-mass spectrometry (GC-MS) were utilized to quantify and classify the types of phenolic derivatives present within the bio-oil. The results showed that active phenols with a content exceeding 70% constituted the largest fraction of the phenol derivatives. The formation of active phenols, especially B-phenols, was enhanced by the incorporation of the catalysts HZSM-5, red mud and dolomite. HZSM-5 and dolomite exhibited the best catalytic effect on the production of A-phenols and B-phenols, respectively. The highest content of C-phenols (47.16%) was achieved when red mud was utilized as a catalyst. With regard to the total content of active phenol derivatives, the catalytic effect of dolomite was better than that of HZSM-5 and red mud. The content of total phenols and active phenols increased as the reaction temperature increased from 450oC to 600oC.

In this study, the dry torrefaction (DT) and wet torrefaction (WT) were compared at different temperatures to explore the effect of these pretreatments on the characteristic of corn stalk digestate (CSD) and the thermal degradation behaviors. The results indicated the both torrefactions improved the fuel properties of CSD, including the lower volatiles content, higher carbon content and HHV. The WT showed higher removals of organics and alkali metals, while DT retained more carbon and ash. The SEM, FTIR and XRD analyses indicated the existence of organic coverings of WT samples, and showed richer surface functional groups, relative complete lignin structure and higher crystallinity compared to DT samples. The thermogravimetric analysis displayed the torrefied temperature above 260 °C (DT) or 220 °C (WT) was not suitable for CSD pyrolysis. Besides, the WT samples showed the more concentrated combustion range, while DT tends the burning of CSD to the behavior of coal.

Polymer nanofibers have a great potential in PM2.5 filtration, but they generally cannot remove particulate matter (PM) particles directly from high-temperature sources due to their vulnerable structure. Polysulfonamide (PSA)/polyacrylonitrile (PAN) composite nanofibers that can withstand a temperature up to 400 °C, were fabricated by a simple electrospinning method. The interactions between PSA and PAN defined the resulting microarchitecture and shape of the nanofibers when suffering heating. The PSA/PAN composite nanofibers exhibited above 99.7% removal efficiency for the PM2.5. More importantly, such a high PM2.5 removal efficiency was well retained even after heating the nanofibers at temperatures ranging between 100 °C and 400 °C. The nanofiber air filter could continuously work for 100 h in an environment with the concentration of PM2.5 approaching 380 μg/m3. The good thermal stability and high filtration efficiency of PSA/PAN nanofibers make them attractive in various applications, especially when high-temperature bearable polymer components are needed.

Conjugated polymers consisting of diketopyrrolopyrrole (DPP) units have been successfully applied in field-effect transistors (FETs) and polymer solar cells (PSCs), while most of the DPP polymers were designed as symmetric structures containing identical aromatic linkers. In this manuscript, we design a new asymmetric DPP polymer with varied aromatic linkers in the backbone for application in FETs and PSCs. The designation provides the chance to finely adjust the energy levels of conjugated polymers so as to influence the device performance. The asymmetric polymer exhibits highly crystalline properties, high hole mobilities of 3.05 cm2 V–1 s–1 in FETs, and a high efficiency of 5.9% in PSCs with spectra response from 300 to 850 nm. Morphology investigation demonstrates that the asymmetric polymer has a large crystal domain in blended thin films, indicating that the solar cell performance can be further enhanced by optimizing the microphase separation. The study reveals that the asymmetric design via adjust...

Fluorinated conjugated polymers have been widely used in high performance polymer solar cells, but they showed limited application in field-effect transistors (FETs). In this paper, we focus on the influence of fluorine atoms upon charge transport of conjugated polymers in FET devices. Two series of conjugated polymers without or with fluorine atoms were designed and applied into FETs. Nonfluorinated conjugated polymers show high hole mobilties up to 11.16 cm2 V–1 s–1, while fluorinated polymers exhibit low hole mobilities below 1.80 cm2 V–1 s–1. Further investigation by differential scanning calorimetry (DSC) and 2D grazing-incidence wide-angle X-ray scattering (2D-GIWAXS) reveal that fluorinated conjugated polymers show low crystallinity and “face-on” orientation in thin films, explaining their poor hole mobilities in FET devices. Our results clearly show how the chemical structures influence the charge transport properties, which can be used to design new conjugated polymers toward high performance FETs.

The influence of the chemical structure of conjugated polymers on the nanophase separation and device performance in fullerene-based solar cells has been widely studied, while this is less investigated in non-fullerene solar cells. In this work, we design three conjugated polymers with different length of side chains, and we find that the length of side chains has little influence on the quantum efficiencies of non-fullerene solar cells. As a comparison, the length of side chains has a significant effect on the quantum efficiencies of fullerene-based solar cells. This indicates that morphology of the blended thin films in non-fullerene solar cells is rather independent of the length of the donor side chains, and the mechanism for morphology evolution in the non-fullerene system is completely different from that in the fullerene system. Our conclusion is confirmed by a variety of advanced characterization techniques. The studies reveal that in blended thin films based on the non-fullerene material the donor polymers with different side chains have a similar coherence length of π-π stacking, crystal size and domain purity, giving rise to similar internal quantum efficiency and power conversion efficiency of the solar cells.

Diketopyrrolopyrrole (DPP)-based conjugated polymers have been successfully applied in high performance field-effect transistors and fullerene-based solar cells, but show limited application in non-fullerene solar cells. In this work, we use four DPP polymers as electron donor and a perylene bisimide dye as electron acceptor to construct non-fullerene solar cells. The donors and acceptor have complementary absorption spectra in visible and near-infrared region, resulting in broad photo-response from 300 nm to 1000 nm. The solar cells were found to provide relatively low power conversion efficiencies of 1.6–2.6%, which was mainly due to low photocurrent and fill factor. Further investigation reveals that the low performance is originated from the high charge recombination in photo-active layers. Our systematical studies will help better understand the non-fullerene solar cells based on DPP polymers and inspire new researches toward efficient non-fullerene solar cells with broad photo-response.

A series of six diketopyrrolopyrrole (DPP) based conjugated polymers with a varying content of solubilizing perfluoroalkyl chains were synthesized. Based on a systematic investigation of the influence of the solvent on the photovoltaic performance, it is found that 1,6-diiodoperfluorohexane (IC6F12I) is an effective solvent additive to enhance the power conversion efficiency (PCE) of DPP polymers with perfluoroalkyl side chains. The polymers consist of thiazole-flanked DPP units that alternate along the main chain with varying ratios of thiophene (T) and perfluoroalkyl benzodithiophene (FBDT) units. The polymers possess high molecular weights, narrow band gaps and good crystalline properties. The DPP polymers were used as electron acceptors in bulk heterojunction solar cells with another DPP polymer as the electron donor. A solvent mixture of CHCl3 : 1-chloronaphthalene (1-CN) is found to provide the best PCE of 2.9% in non-fluorine based DPP polymer solar cells, but yields a low PCE of 0.52% for perfluoroalkyl-containing polymer solar cells. Perfluoroalkyl-containing polymer solar cells fabricated from CHCl3 with IC6F12I as the processing additive show a significantly improved PCE of 2.1%. The morphology analysis of the blend films reveals that IC6F12I as an additive improves the micro-phase separation between the polymer donor and acceptor, which results in enhanced charge generation.

Four typical diketopyrrolopyrrole (DPP)-based conjugated polymers were used as electron donors in all-polymer solar cells (PSCs) with a naphthalenediimide-based polymer N2200 as the electron acceptor. The four DPP polymers have near-infrared absorption spectra up to 1000 nm and suitable energy levels for charge separation from donor to acceptor. DPP polymer : N2200 cells were found to have high open circuit voltages in comparison to fullerene-based solar cells but with low short circuit current densities and fill factors, so that the power conversion efficiencies of these cells were relatively low (0.45–1.7%). These blends relatively had balanced but low hole and electron mobilities from space charge limit current measurements, small surface roughness, and highly quenched photoluminescence (PL) from steady-state PL. These studies show that the low photocurrent and performance arise from the miscibility of the DPP and N2200 polymers, which enhances the charge recombination. The finding was further confirmed by grazing incidence X-ray diffraction and resonant soft X-ray scattering. All the PSCs based on DPP polymers were investigated, opening further studies based on these systems due to the broad absorption, high carrier mobilities and good crystalline properties of DPP polymers.

Conjugated polymers with LUMO levels of −4.00 eV combined with a newly designed perylene bisimide compound with a LUMO level of −4.56 eV were found to have efficient charge transfer and provide power conversion efficiencies up to 1.4% in solar cells.

In this paper, we designed, synthesized, and characterized a set of non-fullerene small molecules based on bis(perylene diimide) with DACH bridge. Theoretical calculations make clear that the introduction of the DACH bridge into PPDI forms a U-shape framework, with pi–pi interactions between PDIs. We investigate the performances of non-fullerene solar cells comprising racemic and enantiomerically pure DACH-PPDIs as the electron acceptor and PTB7-Th as the electron donor. As a consequence, a power conversion efficiency (PCE) of 4.68% is achieved with inverted device architecture. Furthermore, the device behaviour, morphological feature and charge transport properties were also investigated. It is a potential way to design highly efficient non-fullerene organic solar cell by tuning the structure of PDI to reach highly efficient photovoltaic performances.

Although lots of works have been done on the hydrolysis of synthetic biodegradable polymers, the methods for monitoring the degradation process still suffer from some disadvantages, especially in terms of detection speed and non-invasive manners. In this work, a fast, non-invasive visualization monitoring platform was developed for hydrolytic degradation of bio-degradable polymers based on aggregation-induced emission (AIE) technique. We synthesized and introduced an amphiphilic AIE probe to the commercial polylactide (PLA) matrix through a simple co-precipitation process. Amphiphilic AIE probes gradually entered the aqueous media during the hydrolytic degradation process of PLA matrix, which exhibited fluorescence evolution. The variation of fluorescence emission corresponding to the evolution of PLA mass loss could be easily observed by naked eyes. Compared to traditional characterization techniques based on mass loss and molar mass measurements by sampling, this method is sensitive, fast and non-invasive, and has the potential to become a standard method for commercial bio-degradable product testing.

Three dimensional (3D) printing materials were manufactured with polylactic acid (PLA) and poplar powder using the twin screw extruder and 3D printing consumables extruder. Lubricant (TPW604) and toughening agent polyolefin elastomer (POE) were utilized to improve the fluidity and toughness of the materials. 3D printing materials were tested by infrared spectroscopy, X-ray diffraction, melt flow rate, rheology behavior, impact and scanning electron microscope. The results show that the poplar powder could decrease impact strength of PLA, the same as TPW604. Unlike poplar powder, TPW604 can improve the fluidity of 3D printing materials. And POE can fill the voids formed by poplar powder in PLA, enhance interface compatibility between poplar powder and PLA, and effectively improve the fluidity and impact strength of 3D printing materials.

Polymer nanowires based on two diketopyrrolopyrrole conjugated polymers with similar chemical structures are shown to have distinct "edge-on" and "face-on" configurations in addition to high well-balanced hole and electron mobilities of 5.47 and 5.33 cm(2) V(-1) s(-1) in field-effect transistors.

Five wide or medium band gap diketopyrrolopyrrole (DPP)-based conjugated polymers with pyridine as bridges were developed for organic field-effect transistors (OFETs) and polymer solar cells (PSCs). By introducing copolymerized aromatic building blocks from strong electron-donating units to electron-deficient units into the conjugated backbone, the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) levels of the DPP polymers were tailored to the low-lying position. Therefore, the polarity of charge transport in OFETs can be switched from p-type to n-type. The DPP polymer with a low-lying LUMO of −3.80 eV provides a hole-only mobility of 2.95 × 10−2 cm2 V−1 s−1, while an electron-only mobility of 1.24 × 10−3 cm2 V−1 s−1 is found in the DPP polymer with a LUMO of −4.22 eV. Further investigation of photovoltaic cells based on these DPP polymers shows a modest power conversion efficiency (PCE) of around 2%. Our results demonstrate that wide band gap pyridine-bridged DPP polymers have potential application in OFETs and OSCs by adjusting their energy level with alternated units on the conjugated backbone.

Three thiazole-bridged DPP polymers with deep lowest unoccupied molecular orbital (LUMO) levels were designed for field-effect transistors (FETs) and polymer–polymer solar cells. By introducing thiazole–thiazole coupled segments, perfluoroalkyl side chains or strong electron-deficient naphthalenediimide units into the conjugated backbone the three thiazole-bridged DPP polymers have LUMO levels of −4.0 to −4.4 eV. The three DPP polymers exhibit optical absorption in the near-infrared region, crystallinity and an electron mobility of around 0.01 cm2 V−1 s−1 in bottom contact FETs. The polymers were applied as electron acceptors in polymer–polymer solar cells to provide PCEs of around 0.4%. The low PCEs are mainly due to low short-circuit currents (Jsc) and attributed to large phase separation. Our results demonstrate several efficient strategies to lower the energy levels of conjugated polymers in order to be used as universal acceptors for photovoltaic cells.

Hydrogen production via catalytic steam reforming of maize stalk fast pyrolysis bio-oil over the nickel/alumina supported catalysts promoted with cerium was studied using a laboratory scale fixed bed coupled with Fourier transform infrared spectroscopy/thermal conductivity detection analysis (FTIR/TCD). The effects of nickel loading, reaction temperature, water to carbon molar ratio (WCMR) and bio-oil weight hourly space velocity (WbHSV) on hydrogen production were investigated. The highest hydrogen yield of 71.4% was obtained over the 14.9%Ni-2.0%Ce/A12O3 catalyst under the reforming conditions of temperature = 900 °C, WCMR = 6 and WbHSV = 12 h−1. Increasing reaction temperature from 600 to 900 °C resulted in the significant increase of hydrogen yield. The hydrogen yield was significantly enhanced by increasing the WCMR from 1 to 3, whereas it increased slightly by further increasing WCMR. The hydrogen yield decreased with the increase of WbHSV. Meanwhile, the coke deposition percentage changed little with increasing WbHSV up to 12 h−1 and then it increased by 4.5% with the further increase of WbHSV from 12 to 24 h−1.

Dibutyl-perylene-3,4-anhydride-9,10-dicarbonylate (1) as an asymmetrical intermediate was synthesized in 80% yield by precipitation of the less soluble target molecule, which was formed through acidic hydrolysis of tetraesters of perylene tetracarboxylic acids at one side in a mixed solvent system. Based on the intermediate, two other asymmetrical intermediates 2 and 3 with monoimide group were also synthesized in high yields. The mono-bromination and di-bromination of 3 typical intermediates could be controlled by using different bromine concentration. The chemical structures of the brominated products and ratios of their isomers were confirmed directly or deduced from their phenol substituted products with MS and NMR spectra. The bromination of the intermediates mainly afforded isomers, but intermediates 1 and 2 could afford unique di-brominated product and mono-brominated product respectively. The bromination of the intermediates led to only slight changes in absorption spectra, but relatively obvious changes in emission spectra.

Mono-substituted perylene bisimides were synthesized in high yields under mild condition. The starting material was mono-nitrified perylene bisimides instead of usual perylene bisimides halogenated at different levels. Besides phenols and amine, the nucleophilic reagents included alcohol and thiol. The substitution of nitro group was easier and more effective than the substitution of halogen atoms. But the substitution reaction of pyrrolidine afforded mono- and 1,6-disubstituted perylene bisimides owing to the high activity of nitrified perylene bisimides and pyrrolidine. Several replacement reactions between phenols and alcohol based on phenol mono-substituted perylene bisimide were also found. The replacement reactions between phenols was fast and in high yield. The absorption of the mono-substituted perylene bisimides were tunable in the whole visible region.

Polyethylene terephthalate (PET) has been modified by Si ion implantation with a dose ranging from 1 × 10 16 to 2 × 10 17 ions /cm 2 using a metal vapor vacuum arc（MEVVA）source. The surface morphology was observed by atomic force microscopy (AFM). The change in the microstructure of Si implanted PET was observed with a transmission electron microscope (TEM). It is believed that the change would improve the conductive properties and wear resistance. The electrical properties of PET have been improved via Si ion implantation. The resistivity of implanted PET decreased obviously with an increase in ion dose. When Si ion dose was 2 × 10 17 cm -2 , the resistivity of PET could be less than 7.9 W·m. The surface hardness and modulus increased obviously. The mechanical property of the implanted PET has been modified greatly. The hardness and modulus of Si implanted PET with a dose of 2 × 10 17 /cm 2 are 12.5 and 2.45 times greater than those of pristine PET, respectively. The area of cutting groove for Si implanted PET is narrower and shallower than those of the unimplanted PET. So the wear resistance is greatly raised. In comparison with metal ion implantation, the improvement of mechanical properties is obvious in ion implantation into PET. Si ion beam modification mechanism of PET is discussed.