In this review, the synthesis and optoelectronic properties of various π‐conjugated‐, σ‐conjugated‐, pendanted‐, and hyperbranched or dendritic silole‐containing polymers (SCPs) are described. So ...far, substituted silole, dibenzosilole, dithienosilole, and bis‐silicon‐bridged stilbene have been incorporated into SCPs. The tunable bandgaps from 4.0–1.55 eV, variable fluorescent colors from UV to blue, green, and red (RGB) light, fluorescent chemo‐sensors for 2,4,6‐trinitrotoluene (TNT)‐type explosives, aggregation‐induced emission, efficient electroluminescence emissions for RGB lights, phosphorescent hosts with high triplet energy level, efficient solar cells, stable field‐effect transistors with high hole mobility in air, and attenuation of strong laser power, are the important features of SCPs.
Side‐chain engineering has been proved to show profound impact on polymer properties and blend morphology. Herein, the critical role of siloxane‐terminated alkoxy side chains was revealed by a tiny ...decorating method through which the molar content of siloxane‐terminated alkoxy side chain was fixed to 5 %, and its alkyl linker was the only tuning factor. The pentylene, heptylene, and nonylene linkers were designed and used to synthesize wide‐bandgap polymers PQSi505, PQSi705, and PQSi905, respectively. Interestingly, the siloxane pendant of combinatory side chain exhibited a distinct impact on molecular packing when its branching position shifted slightly. Among the three polymers, PQSi705 had the strongest aggregation and the highest packing order. Finally, toluene‐processed organic solar cells (OSCs) based on PQSi705 and Y6‐BO achieved the best power conversion efficiency of 15.77 %. This work suggests that siloxane pendant can serve as a powerful modulator to enhance the photovoltaic performance of OSCs.
Small change: The critical role of siloxane pendant in combinatory side chain is addressed by a tiny decorating method, where the molar content of siloxane‐terminated side chain is set to 5 %. Changing the alkyl linker from pentylene to heptylene and then to nonylene, the detailed investigation reveals the powerful functionality of siloxane pendant toward green solvent processed nonfullerene solar cells.
Nonfullerene-based organic solar cells （NFOSCs） have received great interest recently due to their higher performance and greater potential compared with fullerene-based solar cells 1. Power ...conversion efficiencies （PCEs） over 13% have been realized in single-junction NFOSCs 2. Compared with traditional fullerene acceptors, the greatest advantage of nonfullerene acceptors is their stronger light-harvesting capability in the visible and near-infrared （NIR） regions, which helps to generate high photocurrent for solar cells. By assembling a carbon-bridged ladder-type electron- donating unit （D）, such as indacenodithiophene （IDT）, with two electron-accepting end groups （A）, such as 1,1-dicyanomethy- lene-3-indanone （It）,
The liquefaction of paulownia in hot compressed water with and without the presence of catalysts such as Fe and Na2CO3 was studied to investigate the catalyst’s effects on the biomass liquefaction ...process. Experiments were conducted in a 1000 ml stainless steel autoclave in the conditions of temperature range of 280–360 °C for 10 min under vacuum, with 60 g biomass and 360 g water, respectively. All the catalysts tested, i.e., Na2CO3 and Fe, were found effective for enhancing the formation of heavy oil products, while they significantly promoted the formation of gas. The experimental results showed that the maximum heavy oil yield rate was 36.34% with Fe catalyst and the minimum solid residue yield was obtained when Na2CO3 was employed as catalyst. The heavy oils from with and without catalyst were characterized by GC–MS and FTIR. The results showed that the oils mainly contained phenol derivatives, ketones, carboxylic acid/ester, benzene derivatives and long-chain alkanes, aldehydes and its derivatives and that employing different catalysts could change the distribution and relative abundance of produced compounds.
Three series of low‐bandgap polymers based on a novel quinoidal para‐azaquinodimethane (p‐AQM) unit are devised and synthesized, enabling an in‐depth study of the impact of structural factors such as ...polymer main chain, branching point of the side chain, and the length of the branch chains on the thin film morphologies and charge transport properties. Morphological studies reveal that the polymers composed of larger repeating units exhibit a stronger tendency to form edge‐on lamella. On the other hand, altering the side chain structures of polymers with the same main chain configuration indicates that the branching point position has a more deterministic impact than the branch chain length on the interchain interactions and the crystallite orientation. These results demonstrate a compound odd‐even effect of the branching point on the chain packing and morphology, which correlates well with the corresponding field effect transistor performances. The polymer with the branching point at the fourth carbon displays the highest charge carrier mobility over 1.0 cm2 V−1 s−1, concurrent with a bimodal texture. This study provides a comprehensive description of the correlations between polymer structures, thin film morphology, and device performances, providing a clear path to desirable bimodal thin film texture for charge transport.
Comparative studies of series of quinoidal polymers with varying main chain or side chain moieties have provided a comprehensive description of the relationship between polymer structures, thin film morphologies, and charge transport properties. A compound “odd‐even” branching point effect is observed experimentally and elucidated theoretically. Such studies provide a unique insight for the future design of high‐performing organic semiconductors.
Alternating and random conjugated copolymers with a siloxane-terminated side chain for a repeating unit based on 5,6-difluoro2,1,3benzothiadiazole (FBT) and quarterthiophene (4T) were synthesized, ...among which side-chain random copolymers PFBT4T-C5Si-50% and PFBT4T-C5Si-25% with low contents of 50% and 25% siloxane-terminated side chains, respectively, in conjunction with alkyl side chains were found to be more suitable for optoelectronic applications due to good film-forming in solution processing. Grazing incidence X-ray diffraction (GIXD) indicated that the siloxane-terminated side chain could induce PFBT4T-C5Si-50% and PFBT4T-C5Si-25% with face-on orientations, giving high 3-D hole transport in neat films as supported by a high hole mobility up to 2.46 cm
2
V
−1
s
−1
in field-effect transistors and an SCLC hole mobility up to 5.9 × 10
−2
cm
2
V
−1
s
−1
in hole-only devices. Fast SCLC hole and electron transports were seen for their bulk-heterojunction (BHJ) blend films with PC
71
BM as the acceptor, due to the retention of a polymer face-on orientation. The BHJ blend film of PFBT4T-C5Si-25% showed lower film surface roughness, more balanced hole and electron transport, and relatively smaller phase separation when compared with PFBT4T-C5Si-50%, as evidenced by atomic force microscopy (AFM), transmission electron microscopy (TEM), SCLC, and resonant soft X-ray scattering (RSoXS) measurements. The PFBT4T-C5Si-25%-based PSCs with 270, 420, and 600 nm thick active layers exhibited outstanding power conversion efficiencies (PCEs) of 10.39%, 11.09%, and 10.15%, respectively, readily offering a high thickness tolerance to achieve an unprecedented wide active layer processing window for PCE > 10%. This is also the first PCE of more than 10% achieved by an active layer of a 600 nm thickness level in PSCs. Another notable feature is very high fill factors of more than 74% and 71% being achieved for very thick active layers of 420 and 600 nm, respectively. The results suggest that side-chain engineering through the incorporation of a partial siloxane-terminated side chain is a unique handle to afford new photovoltaic polymers with enhanced vertical carrier transport towards application in roll-to-roll processing of PSCs.
This work presents the simulated equilibrium compositions of ethanol steam reforming (SR), partial oxidation (POX) and auto-thermal reforming (ATR) at a large temperature range, steam-to-ethanol and ...oxygen-to-ethanol molar ratios. The simulation work shows that the moles of hydrogen yield per mole ethanol are of this order: SR > ATR > POX. The results are compared with other simulation works and fitted models, which show that all the simulation results obtained with different methods agree well with each other. And the fitted models are in highly consistency with very small deviations. Moreover, the thermal-neutral point in corresponding to temperature, steam-to-ethanol and oxygen-to-ethanol mole ratios of ethanol ATR is estimated. The result shows that with the increasing of oxygen-to-ethanol mole ratio, the T-N point moves to higher temperatures; with the increasing of steam-to-ethanol mole ratio, the T-N point moves to lower temperatures. Furthermore, the energy exchanges of the reforming process and the whole process and the thermal efficiencies are also analyzed in the present work and that the energy demands and generated in the whole process are greater than the reforming process can be obtained. Finally, the optimum reaction conditions are selected.
► The equilibrium compositions simulated by different researchers with different methods are compared. ► The simulation results are fitted with polynomials for convenient reference. ► The energy balance and thermal efficiencies are analyzed. ► The optimum reaction conditions of ethanol POX, SR and ATR for hydrogen production are selected.
Solar cells are one attractive method for harnessing inexhaustible clean energy from the sun. Organic photovoltaic technology is emerging as a potential competitor to silicon-based photovoltaic cells ...(PVCs), and their power conversion efficiencies (PCE) can now exceed 6%. Polymeric bulk-heterojunction (BHJ) PVCs, whose photoactive layer is composed of a blend of bicontinuous and interpenetrating donors and acceptors, can maximize interfacial area between the donor and the acceptor. Classic polymer donors, such as dialkoxy-substituted poly(para-phenylene vinylene)s (PPVs) and poly(3-hexylthiophene) (P3HT), have been widely investigated. However, advances in synthetic methodology provide new avenues for the development of novel conjugated polymer donors with improved power conversion efficiencies. Recently, researchers have achieved great advances in this area. This Account primarily focuses on novel donor polymers that have shown power conversion efficiencies greater than 1%. 2,1,3-Benzothiadiazole, thiophene, thieno3,4-bpyrazine, quinoxaline, and silole have emerged as useful heterocycles for constructing a variety of conjugated polymers for photovoltaic applications. We summarize useful information, such as molecular weights, absorption, bandgap, energy levels, and their photovoltaic performances with detailed device parameters (see comparison tables), about these novel donor polymers. We use statistical summaries to evaluate several important parameter relationships among these polymer donors including open-circuit voltage versus HOMO, power conversion efficiency versus bandgap, and power conversion efficiency versus hole mobility. Further statistical analysis of the data listed in these tables may guide further structural design and evaluation of polymer donor materials.
Biomass has been proposed to be an alternative source of fuels for industrial applications. The liquefaction of paulownia was studied in hot-compressed water with iron catalyst at temperatures ...ranging from 280 to 360
°C, using a 1000
ml stainless steel autoclave with a magnetic stirrer. With an increase of the reaction temperature, the yield of heavy oil increased and then decreased. The maximum yield of heavy oil of 36.34
wt.% was obtained at 340
°C. The experimental results show that the reaction temperature significantly influenced the process of biomass liquefaction. The liquid products and solid residues produced at various reaction temperatures were analyzed using Fourier transform infrared (FTIR) spectrophotometer and the heavy oil got at 340
°C were analyzed using gas chromatograph with mass selective detector (GC–MS), respectively. The analytical results show that the heavy oil and water-soluble oil is complicated compound. The water-soluble oil mainly contains carbohydrates, acetic acid, alcohols, aldehydes and pyran derivatives. In addition, the heavy oil mainly consists of phenol and its derivatives, ketone, long-chain carboxylic acids/esters, benzene derivatives and long-chain alkanes.
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