Search

We report a facile, solvent-free surfactant-dependent mechanochemical synthesis of highly luminescent CsPbBr3 nanocrystals (NCs) and study their scintillation properties. A small amount of surfactant oleylamine (OAM) plays an important role in the two-step ball milling method to control the size and emission properties of the NCs. The solid-state synthesized perovskite NCs exhibit a high photoluminescence quantum yield (PLQY) of up to 88% with excellent stability. CsPbBr3 NCs capped with different amounts of surfactant were dispersed in toluene and mixed with polymethyl methacrylate (PMMA) polymer and cast into scintillator discs. With increasing concentration of OAM during synthesis, the PL yield of CsPbBr3/PMMA nanocomposite was increased, which is attributed to reduced NC aggregation and PL quenching. We also varied the perovskite loading concentration in the nanocomposite and studied the resulting emission properties. The most intense PL emission was observed from the 2% perovskite-loaded disc, while the 10% loaded disc exhibited the highest radioluminescence (RL) emission from 50 kV X-rays. The strong RL yield may be attributed to the deep penetration of X-rays into the composite, combined with the large interaction cross-section of the X-rays with the high-Z atoms within the NCs. The nanocomposite disc shows an intense RL emission peak centered at 536 nm and a fast RL decay time of 29.4 ns. Further, we have demonstrated the X-ray imaging performance of a 10% CsPbBr3 NC-loaded nanocomposite disc.

There is a growing desire for wearable sensors in health applications. Fibers are inherently flexible and as such can be used as the electrodes of flexible sensors. Fiber-based electrodes are an ideal format to allow incorporation into fabrics and clothing and for use in wearable devices. Electrically conducting fibers were produced from a dispersion of poly (3,4-ethylenedioxythiophene)-poly (styrenesulfonate) (PEDOT: PSS). Fibers were wet spun from two PEDOT: PSS sources, in three fiber diameters. The effect of three different chemical treatments on the fibers were investigated and compared. Short 5 min treatment times with dimethyl sulfoxide (DMSO) on 20 µm fibers produced from Clevios PH1000 were found to produce the best overall treatment. Up to a six-fold increase in electrical conductivity was achieved, reaching 800 S cm-1, with no loss of mechanical strength (150 MPa). With a pH-sensitive polyaniline coating, these fibers displayed a Nernstian response across a pH range of 3.0 to 7.0, which covers the physiologically critical pH range for skin. These results provide opportunities for future wearable, fiber-based sensors including real-time, on-body pH sensing to monitor skin disease., Postprint (author's final draft)

Plasma processing, as a commercial and large-scale technology, was used to functionalize few-layer graphene (FLG) and multi-walled carbon nanotubes (MWCNT). The successful functionalities of FLG and MWCNT have been confirmed by elemental microanalysis, X-ray photoelectron spectroscopy, acid-base titration and zeta potential measurements. With the assistance of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT/PSS), a water-dispersible and conductive polymer, a composite of functionalized FLG and MWCNT was fabricated into large-size flexible films and also interdigitated microelectrodes for microsupercapacitor application via simple and scalable techniques (i.e. doctor blading and laser-etching). When normalised by volume and area, the devices made from FLG(NH3)-MWCNT(Acid) (19.9 F cm−3 at 5 mV s−1 and 12.2 F cm−3 at 200 mV s−1) and FLG-MWCNT(Acid) (19.5 mF cm−2 at 5 mV s−1 and 12.8 mF cm−2 at 200 mV s−1) show the best performing composites, respectively, indicating how effective functionalization of FLG and MWCNT is for the enhancement of electrochemical capacitance. In-situ Raman microscopy confirmed the reversible pseudo-capacitive behaviour of electrode materials and the stable electrochemical performance of the devices. The facile techniques used in this work and the good device performances show their great potential for wearable applications.

Peer Reviewed, Postprint (author's final draft)

Flexible fibre supercapacitors were fabricated by wet-spinning from carbon nanotube/carbon black dispersions, followed by straightforward surface treatments to sequentially deposit MnO2 and PEDOT:PSS to make ternary composite fibres. Dip coating the fibres after the initial wet-spinning coagulation creates a simple solutionbased continuous process to produce fibre-based energy storage. Well-controlled depositions were achieved and have been optimised at each stage to yield the highest specific capacitance. A single ternary composite fibre exhibited a specific capacitance of 351 F g-1. Two ternary composite fibre electrodes were assembled together in a parallel solid-state device, with polyvinyl alcohol/H3PO4 gel used as both an electrolyte and a separator. The assembled flexible device exhibited a high specific capacitance of 51.3 F g-1 with excellent both chargedischarge cycling (84.2% capacitance retention after 1000 cycles) and deformation cycling stability (82.1% capacitance retention after 1000 bending cycles)., Peer Reviewed, Preprint

Flexible microcomponents are being widely employed in the microelectronic industry; however; they suffer from a lack of complex movement. To address this problem, we have developed flexible, electrically conductive, magnetic composite fibres showing complex motion in three dimensions with the capacity to be selectively actuated. Flexible carbon-based fibres were prepared by wet-spinning and were subsequently modified by electrodepositing Co-Ni. The high aspect ratio of the fibre (40 µm diameter, 3.5 cm length) causes a directional dependence in the magnetostatic energy, which will allow for anisotropic actuation of the composite. Thus, the application of magnetic fields allows for a precise control of the movement with high reproducibility and accuracy., Peer Reviewed, Preprint

Multilayered flexible fibers, consisting of carbon black–carbon nanotube fibers, manganese oxides, and conducting polymers, are fabricated for use as electrodes in supercapacitors. Carbon-based fibers are initially prepared by wet-spinning using carbon-based nanomaterials (carbon black and carbon nanotubes) and chitosan as a matrix. Subsequent coatings with manganese oxides and conducting polymers form a multilayered structure. Different MnO2 crystalline structures (e-MnO2, ¿-MnO2) are grown onto the fiber by electrodeposition and different conducting polymers (polyethylenedioxythiophene and polypyrrole) used as a conductive wrapping. Each layer improves the performance of the fiber by adding different functionalities. While MnO2 improves the capacitance of the fiber, the presence of conducting polymers creates a conductive network increasing the capacitance further and conferring cycling stability. Capacitance values up 600 F g-1 and capacitance retention of 90% can be achieved with these multilayered hybrid fibers. A symmetric supercapacitor device, prepared from two hybrid fibers, shows no significant change in properties when the device is bent, demonstrating their potential in flexible electronic devices and wearable energy systems., Peer Reviewed, Preprint