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ZnO decorated ZnFe2O4 nanoparticles were synthesized and combined with reduced graphene oxide (rGO) to form ZnFe2O4@ZnO@rGO ternary hierarchical nanocomposites by a controllable method. The microstructure, morphology, and microwave absorption performance of the ZnFe2O4@ZnO@rGO nanocomposites were investigated in detail. The permittivity and permeability of the composites can be effectively regulated by controlling the content of ZnO and rGO to achieve a good impedance matching. Due to the synergistic effect of dielectric loss and magnetic loss, the ZnFe2O4@ZnO@rGO nanocomposites exhibited strong wave absorption and wide absorption bandwidth. The optimal reflection loss (RL) of the ZnFe2O4@ZnO@rGO nanocomposites reached −35.2 dB at 12.0 GHz with a thickness of 2.0 mm and the effective absorption bandwidth was 3.7 dB. The ZnFe2O4@ZnO@rGO hierarchical architecture produced lots of heterogeneous interfaces which made a significant contribution to the wave absorption performance. The combination of interfacial polarization, dipole polarization, and eddy current loss enhanced the microwave absorption capacity of the ZnFe2O4@ZnO@rGO system. This work provides a feasible approach for the design and preparation of wave absorption materials with tunable permittivity and permeability.

Currently, the microwave absorption materials with high absorbing efficiency are in urgent need to reduce electromagnetic pollution. Herein, the ZnFe2O4@SiO2 core–shell microspheres were synthesize...

Low-dielectric polymer composites with high mechanical and thermal properties are very promising for microelectronic devices application. In this paper, chloride salt of octa (aminopropylsilsesquioxane) was prepared successfully and then was grafted onto silane modified boron nitride (BN). The hybrids were used to prepare epoxy-based composites and the dielectric, thermal and tensile properties of the composites were studied. Results revealed that the dielectric constant and dielectric loss values of the epoxy composites were decreased, and the AC resistivity was increased by adding only 0.6 wt% of the hybrids. Moreover, the epoxy composite exhibited improved thermal stability and higher glass transition temperature compared with the pure epoxy. The tensile strength, tensile modulus, and elongation at break of the epoxy composites were increased by 19.7%, 15.5%, and 69.7% compared with that of pure epoxy, respectively, when the hybrids loading was 0.6 wt%. These results indicated that hybridization of polyhedral oligomeric silsesquioxane and BN was beneficial to take their advantages for preparing high performance low-dielectric epoxy composites.

An asymmetrical tri-petal lilac-like platform based on perylene bisimide (PBI) was designed and synthesized to further perform the ether-exchange reaction, while common tetraphenoxy PBI analogue cannot do it. We found that the tri-petal lilac-like platform strategy not only avoids the regioisomers of difunctionalized PBI, but also is a precise and facile way to achieve regioselective introduction of alkyloxy, alkylthio and C=C double bond ended substituents onto the 1-position of perylene bay without the use and removal of the protecting groups. Due to the tunable photoelectrical properties and functional groups at bay position, these n-type PBI derivatives are promising materials for photovoltaic and supramolecular application.

Poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT: PSS) films were post-treated with polar solvent dimethylsulfoxide (DMSO) by spin-coating method and polymer solar cells (PSCs) based on poly [N-9″]-hepta-decanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole) (PCDTBT) : [6,6]-phenyl C71-butyric acid methyl ester (PC71BM) were fabricated to investigate the effect of the treatment. By post-modifying the PEDOT: PSS layer, the conductivity of the PEDOT: PSS film was largely improved. Using electrochemical impedance spectroscopy (IS) we observed that the series resistance of the device decreased greatly after the treatment. With DMSO-treated PEDOT: PSS transport layer, the power conversion efficiency (PCE) of the PSC based on PCDTBT: PC71BM raised from 5.95% to 6.52% with both increase in Jsc and FF. We systematically studied charge transport property via space-charge-limited-current (SCLC) and our results suggest that the increment in device efficiency can be attributed to the increased hole-mobility and thus more balanced charge transport benefits the enhancement of polymer solar cell efficiency. We also noted that if measured without a shadow mask much more overestimation will take place in the DMSO-treated device as a result of lateral electrical conduction. We suggest that when we apply the highly conductive PEDOT: PSS layer in the PSCs, careful measurement should be carried out to avoid inaccuracy.

Two high boiling point solvents namely diphenylether (DPE) and dimethylsulfoxide (DMSO) were employed as co-additives in fabricating poly [N-9″]-hepta-decanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3-benzothiadiazole) (PCDTBT): [6,6]-phenyl C71-butyric acid methyl ester (PC71BM) based polymer solar cells (PSCs). It was found that the power conversion efficiency (PCE) can be improved to 7.13% for the PSCs processed with co-additives in comparison with ~6.5% for the PSCs processed with either DPE or DMSO additives. The enhanced PCE is benefited from simultaneous increase in Voc, Jsc and FF due to the co-additives fabricating process and the two additives are found to improve the photovoltaic performance with different mechanisms.

The theoretical calculations are used to find that D-π-A-π-A style conjugated polymer PC-TBTBT is more efficient for solar cells application than the D-π-A analog PC-TBT because the D-π-A-π-A structure has a narrower band gap and higher molar absorption coefficient and redshift spectrum. Motivated by the theoretical prediction, 5,6-bis(octyloxy)-2,1,3-benzothiadiazole and 2,7-carbazole are adopted to synthesize the D-π-A-π-A style PC-TBTBT (M(w) = 31.1 kDa) and D-π-A analog PC-TBT (M(w) = 87.5 kDa) by Suzuki coupling reaction. Experimental results confirm that D-π-A-π-A PC-TBTBT-based solar cell shows a power conversion efficiency (PCE) of 4.74% with high V(OC) of 0.99 V and enhanced J(SC) of 9.70 mA cm(-2). The PCE and J(SC) achieve improvements of 17% and 26%, respectively, compared to the D-π-A PC-TBT-based solar cell.

By using Heck polycondensation, we have synthesized carbazole-based alt-copolymers tethered with polyhedral oligomeric silsesquioxanes (POSS), which had well-defined architectures, similar polymerization degrees and the different contents of POSS. The effect of POSS content and the length of the side chain containing POSS on the electroluminescence properties of these polymers were investigated. POSS particles in these alt-copolymers showed excellent dispersity and prevented the interchain aggregation of polymers in film state well. Besides, POSS benefited charge balance by increasing the electron current density, which led to a higher luminance and current efficiency, as well as purer blue light-emitting.

Fossil fuel alternatives, such as solar energy, have attracted considerable attention. Polymer-based solar cells hold the promise for their potential use in cost-effective, lightweight, solution-processable, and flexible large area panels. However, morphology controlling remains the core issue to achieve high performance. A series of trifunctionalized perylene bisimide derivatives and poly(triphenylamine-block-anthraquino) copolymer were synthesized for polymer photovoltaic application and characterized by FTIR, UV, GPC, DSC, 13 C and 1 H NMR.