Electromagnetic and Microwave Absorption Properties of Carbonyl-Iron/Fe91Si9 Composites in Gigahertz Range

Carbonyl-iron/Fe91Si9 composites for thin microwave absorbers were firstly prepared by a simple blending technique. The patterns of carbonyl-iron and Fe91Si9 were characterized by scanning electron microscope (SEM). The complex permittivity, permeability and microwave absorption properties of the composites were studied in the frequency range of 2 - 7GHz by a HP8720B vector network analyzer. Complex permittivity and permeability decrease gradually with increasing weight percentage of Fe91Si9 in the composites, the variation of permittivity was very large but the variation of permeability was very small. The composites exhibited excellent microwave absorption properties with increasing Fe91Si9 content. The reflection loss (RL) values less than –20 dB were obtained in the 3.7 - 6.7 GHz frequency range for the paraffin matrix composites with 80 wt% carbonyl-iron/Fe91Si9 powders (weight ratio of carbonyl-iron to Fe91Si9 was 1:1), with thickness of 4.0 - 2.4 mm, respectively. The optimal RL of –45 dB was observed at 5.2 GHz with a matching thickness (dm) of 3.0 mm. The excellent microwave absorption properties were attributed to a better electromagnetic impedance match and a higher electric resistivity.

Effects of Al^3+on pollutant removal and extracellular polymeric substances(EPS)under anaerobic,anoxic and oxic conditions

Aluminum ions produced by aluminum mining,electrolytic industry and aluminum-based coagulants can enter wastewater treatment plants and interact with activated sludge.They can subsequently contribute to the removal of suspended solids and affect activated sludge flocculation,as well as nitrogen and phosphorus removal.In this study,the effects of Al^3+on pollutant removal,sludge flocculation and the composition and structure of extracellular polymeric substances(EPS)were investigated under anaerobic,anoxic and oxic conditions.Results demonstrated that the highest chemical oxygen demand(COD)and total nitrogen(TN)removal efficiencies were detected for an Al^3+concentration of 10 mg/L.In addition,the maximal dehydrogenase activity and sludge flocculation were also observed at this level of Al^3+.The highest removal efficiency of total phosphorus(TP)was achieved at an Ar+concentration of30 mg/L.The flocculability of sludge in the anoxic zone was consistently higher than that in the anaerobic and oxic zones.The addition of Al^3+promoted the secretion of EPS.Tryptophan-like fluorescence peaks were detected in each EPS layer in the absence of Al^3+.At the Al^3+concentration of 10 mg/L,fulvic acid and tryptophan fluorescence peaks began to appear while the majority of protein species and the highest microbial activity were also detected.Low Al^3+concentrations(<10 mg/L)could promote the removal efficiencies of COD and TN,yet excessive Al^3+levels(>10 mg/L)weakened microbial activity.Higher Al^3+concentrations(>30 mg/L)also inhibited the release of phosphorus in the anaerobic zone by reacting with PO4^3-.

Layer-by-layer slot-die coated high-efficiency organic solar cells processed using twin boiling point solvents under ambient condition

Layer-by-layer (LbL) strategy has been developed to form bulk heterojunction (BHJ) structure for processing efficient organic solar cells (OSCs). Herein, LbL slot-die coating with twin boiling point solvents (TBPS) strategy was developed to fabricate highly efficient OSCs, which matches with large-scale, high throughput roll-to-roll (R2R) industrialized mass process. The TBPS strategy could produce high-quality thin film without any additive, leading to the optimized vertical phase separation with interpenetrating nanostructures, as well as the enhanced charge transport and extraction. Thus, the power conversion efficiency up to 14.42% was achieved for [(2,6-(4,8-bis(5-(2-ethylhexyl-3-fluoro)thiophen-2-yl)-benzo [1,2-b:4,5-b′]dithiophene))-alt-(5,5-(1′,3′-di-2-thienyl-5′,7′-bis(2-ethylhexyl)benzo[1′,2′-c:4′,5′-c′]dithiophene-4,8-dione)]:2,2′-((2Z,2′Z)-((12,13-bis(2-ethylhexyl)-3,9-diundecyl-12,13-dihydro-[1,2,5]thiadiazolo[3,4-e]thieno[2″,3″:4″,5″]thieno[2′,3′:4,5]pyrrolo[3,2-g]thieno[2′,3′:4,5]thieno[3,2-b]indole-2,10-diyl)bis(methanylylidene)) bis(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile (PM6:Y6) OSCs fabricated via sequentially LbL slot-die coating using the TBPS strategy under ambient condition. The research provides a potential route for industrialized production of high-efficiency and large-area OSC devices.

Thermoplastic elastomer enhanced interface adhesion and bending durability for flexible organic solar cells

Stable interface adhesion and bending durability of flexible organic solar cells(FOSCs)is a basic requirement for its real application in wearable electronics.Unfortunately,the device performance always degraded during continuous bending.Here,we revealed the weak interface adhesion force between MoO_(3) hole transporting layer(HTL)and the organic photoactive layer was the main reason of poor bending durability.The insertion of an interface bonding layer with a thermoplastic elastomer,polystyrene-blockpoly(ethylene-ran-butylene)-block-polystyrene(SEBS)effectively improved the interface adhesion force of MoO_(3) HTL and the active layer and decreased the modulus,which ensured higher than 90%of the initial efficiency remaining after 10000 bending.Meanwhile,the FOSCs gave an efficiency of 14.18%and 16.15%for the PM6:Y6 and PM6:L8-BO devices,which was among the highest performance of FOSCs.These results demonstrated the potential of improving the mechanical durability of FOSCs through thermoplastic elastomer interface modification.