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This work presents the synthesis of PANI-PVA-ZnS nanocomposite films by gamma irradiation approach. The samples were irradiated with different doses ranging from 10 kGy to 40 kGy. Subsequently, structural, morphological, optical and electrical characteristics of the samples were investigated. Fourier transform infrared (FT-IR) spectroscopy was employed to study the chemical structure of the samples. Field emission scanning electron microscopy (FE-SEM) was used to investigate the morphology of nanocomposites. The electronic absorption characteristics of the samples were measured by means of UV-Vis spectroscopy. The AC and DC electrical behaviors of the samples were characterized using LCR meter in the frequency range of 20 Hz to 1 MHz. The impedance values of the samples were extracted from Cole-Cole plots and consequently DC conductivity was calculated.

In this study, we investigate the nanoscale effects of photochemically active additives of benzoquinone (BQ), hydroquinone (HQ), and tetracyanoquinodimethane (TCNQ) on grain boundaries in CH3NH3PbI3 solar cells. We employ scanning probe microscopy under light illumination, in particular Kelvin probe force microscopy, to study surface potential changes under laser light illumination. The recently found improvement in the efficiency of BQ added solar cells can be clearly seen in vanishing contact potential differences at grain boundaries under illumination, rendering the material more uniform under solar cell operating conditions. These effects are observed for BQ, but not for HQ and TCNQ. Our findings shed light onto halide perovskite materials and the functional additive design for improved solar cell performance.

Bioelectronic materials based on conjugated polymers are being developed in the hope to interface with electroresponsive tissues. We have recently demonstrated that a polyaniline chitosan patch can efficiently electro-couple with cardiac tissue modulating its electrophysiology. As a promising bioelectronic material that can be tailored to different types of devices, we investigate here the impact of varying the synthesis conditions and time of the in situ polymerization of aniline (An) on the sheet resistance of the bioelectronic patch. The sheet resistance increases significantly for samples that have either the lowest molar ratio of oxidant to monomer or the highest molar ratio of dopant to monomer, while the polymerization time does not have a significant effect on the electrical properties. Conductive atomic force microscopy reveals that the patch with the lowest sheet resistance has a connected network of the conductive phase. In contrast, patches with higher sheet resistances exhibit conductive areas of lower current signals or isolated conductive islands of high current signals. Having identified the formulation that results in patches with optimal electrical properties, we used it to fabricate patches that were implanted in rats for two weeks. It is shown that the patch retains an electroactive nature, and only mild inflammation is observed with fibrous tissue encapsulating the patch.

This work describes a fast, clean and low-cost approach to synthesize ZnS–PVA nanofluids consisting of ZnS nanoparticles homogeneously distributed in a PVA solution. The ZnS nanoparticles were formed by the electrostatic force between zinc and sulfur ions induced by gamma irradiation at a dose range from 10 to 50 kGy. Several experimental characterizations were conducted to investigate the physical and chemical properties of the samples. Fourier transform infrared spectroscopy (FTIR) was used to determine the chemical structure and bonding conditions of the final products, transmission electron microscopy (TEM) for determining the shape morphology and average particle size, powder X-ray diffraction (XRD) for confirming the formation and crystalline structure of ZnS nanoparticles, UV–visible spectroscopy for measuring the electronic absorption characteristics, transient hot wire (THW) and photoacoustic measurements for measuring the thermal conductivity and thermal effusivity of the samples, from which, for the first time, the values of specific heat and thermal diffusivity of the samples were then calculated.

The piezoelectric response, conductivity and surface potential of individual grains and grain boundaries in free-standing polycrystalline ZnO nano- and microstructured platelets is studied using scanning probe based techniques on the nanoscale. We find that applied dc electric fields can alter the piezoresponse in individual grains, as well as the local nanoscale conductivity, and invert the relative surface potential at grain boundaries. This can be attributed to defect accumulation at the grain surfaces and at grain boundaries and the associated density of carriers. Together with recently observed below-bandgap photoconductivity at grain boundaries, the presented observation opens new venues for potential nanoelectronic applications that rely on grain and grain boundary engineering and functionality in a wide-bandgap transparent material.

Research reported in this publication was funded by King Abdullah University of Science and Technology (KAUST) and the Australian Research Council (DP190103316).

Silver nanoparticles in chitosan medium were prepared by the chemical reduction method. Silver nitrate and hydrazine were used as the precursor and reducing agent in the present of chitosan as a natural host polymer. The samples are characterized by UV–visible spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM). The measurements of nonlinear optical properties were defined by Z-scan technique using green CW laser beam operated at 532 nm wavelengths. Thermal effect has a dominant role in the overall material nonlinearity with CW laser. It is shown that the synthesized samples have a negative nonlinear refractive index.

Monodispersed spherical CdS nanoparticles stabilized in PVA solution were synthesized by the gamma radiolytic method and found the average particle size increased from 12 to 13 nm with the increment of dose from 10 to 40 kGy. The XRD results show that it has crystalline planes of cubic structure with crystal lattice parameter of 5.832 A. The optical reflectance revealed a band-edge of CdS nanoparticles at about 475 nm and the reflectance wavelength red shifted with increasing dose due to increasing particle size. The thermal conductivity of CdS/PVA nanocomposites measured by the transient hot wire method that revealed a decrement of the thermal conductivity with an increase of dose caused by effect of radiation on crystallinity of the polymer structure.

Gold nanoparticles were prepared in graphene oxide using laser ablation technique. The ablation times were varied from 10 to 40 minutes, and the particle size was decreased from 16.55 nm to 5.18 nm in spherical shape. The nanoparticles were capped with carboxyl and the hydroxyl groups were obtained from Fourier transform infrared spectroscopy. Furthermore, the UV-visible peak shifted with decreasing of nanoparticles size, appearing from 528 nm to 510 nm. The Z-scan technique was used to measure the nonlinear refractive indices of graphene oxide with different concentrations and a gold nanoparticle graphene oxide nanocomposite. Consequently, the optical nonlinear refractive indices of graphene oxide and gold nanoparticle graphene oxide nanocomposite were shifted from1.63×10-9 cm2/W to4.1×10-9 cm2/W and from1.85×10-9 cm2/W to5.8×10-9 cm2/W, respectively.

CdS nanofluids were prepared by the gamma-radiation method at different radiation doses. The samples were characterized by UV–Vis spectroscopy and transmission electron microscopy. The open cell photoacoustic technique was used to measure the thermal effusivity of the CdS nanocomposites. In this technique a He–Ne laser was used as the excitation source and was operated at 632.8 nm with an output power of 70 mW. The precision and accuracy of this technique were initially established by measuring the thermal effusivity of distilled water and ethylene glycol. The thermal-effusivity values of these two samples were found to be close to the values reported in the literature. The thermal effusivity of CdS nanofluids decreased from (0.453 to 0.268) \(\mathrm {W}\cdot \mathrm {S}^{1/2}\cdot \mathrm {cm}^{-2}\cdot \mathrm {K}^{-1}\) with increased dosage of gamma radiation.

Copper oxide (CuO) nanosheets were obtained by a quick-precipitation method using Cu(NO 3 ) 2 and NaOH in the presence of polyvinylpyrrolidone (PVP). Different sizes of CuO nanosheets were achieved by varying the PVP concentration. The crystal structure, morphology, and optical properties of the CuO nanosheets were characterized by X-ray diffraction, transmission electron microscopy, and diffuse reflectance spectroscopy. Higher PVP concentrations produced CuO nanosheets with enhanced crystalline structure, reduced particle size, and enlarged band gap. Nonlinear optical characteristics were examined by the Z -scan technique using a blue continuous wave laser beam operated at 405 nm. Increased PVP concentration from 0.5 wt% to 5 wt% was found to increase the nonlinear refractive index from −2.157×10 −11 to −5.495×10 −11 .

Gamma irradiation is employed for in situ preparation of PVA-PANI-ZnS nanocomposite. The irradiation dose is varied from 10 to 40 kGy at 10 kGy intervals. The XRD result confirms the formation of crystalline phases corresponding to ZnS nanoparticles, PVA and PANI. Field emission scanning electron microscopy shows the formation of agglomerated PANI along the PVA backbone, within which the ZnS nanoparticles are dispersed. UV-visible spectroscopy is conducted to measure the transmittance spectra of samples revealing the electronic absorption characteristics of ZnS and PANI nanoparticles. Photo-acoustic (PA) setup is installed to investigate the thermal properties of samples. The PA spectroscopy indicates a high value of thermal diffusivity for samples due to the presence of ZnS and PANI nanoparticles. Moreover, at higher doses, the more polymerization and formation of PANI and ZnS nanoparticles result in enhancement of thermal diffusivity.

The nanoscale electrical conduction behaviour of single crystal lead titanate (PbTiO3) is investigated. Piezoresponse force microscopy measurements show 180° ferroelectric domains on the surface of the mm-sized crystals that are electrically switchable with tip voltages of the order of ∼10 V. Electrical conductivity at domain walls in these crystals was observed using conductive atomic force microscopy. Naturally occurring 180° domains exhibit current flow along the delineating domain wall. The domain wall current flow shows Schottky-like rectifying behaviour.

Silver/polyvinyl alcohol (PVA) nanocomposites are prepared via quick precipitation method, using hydrazine as a reducing agent. Preparing of silver/PVA nanocomposites by this method is done for the first time. The samples are characterized by Uv-Visible spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM). Nonlinear optical properties are carried out by Z-scan technique using a blue CW laser beam operated at wavelength 405 nm. It is shown that the synthesized samples have negative nonlinear refractive index and the magnitude is in the order of 10^-8. The nonlinear refractive index increases as amount of reducing agent increases.

Monodispersed spherical CdS nanoparticles embedded into polyvinyl alcohol (PVA) films are synthesized by using an in-situ gamma-irradiation-induced method. The formation mechanism of CdS nanoparticles capped by two united cells of PVA is purposed by means of surrounding the CdS nanoparticles with OH bonds of the PVA chain. CdS nanoparticles are found to possess an unusual orthorhombic structure in monoclinic crystalline PVA. The polymer matrix affords protection from agglomeration and controls the particle size. It is found that the distribution of the prepared nanoparticles increases and a narrower size distribution is observed when the gamma radiation is varied from 10 to 50 kGy. While the average size of the nanoparticles is found to be less affected by the variation of the gamma radiation doses. The size range of the synthesized nanoparticles is 14±1 nm. The optical absorption spectra of synthesized CdS nanoparticles in a polymer matrix reveal the blue shift in the band gap energy with respect to CdS bulk materials owing to quantum confinement effect. The photoluminescence study of nanocomposite films shows the green emission arising from the crystalline defects.