X-ray micro-computed tomography as a non-destructive tool for imaging the uptake of metal nanoparticles by graphene-based 3D carbon structures.

Graphene-based carbon sponges can be used in different applications in a large number of fields including microelectronics, energy harvesting and storage, antimicrobial activity and environmental remediation. The functionality and scope of their applications can be broadened considerably by the introduction of metallic nanoparticles into the carbon matrix during preparation or post-synthesis. Here, we report on the use of X-ray micro-computed tomography (CT) as a method of imaging graphene sponges after the uptake of metal (silver and iron) nanoparticles. The technique can be used to visualize the inner structure of the graphene sponge in 3D in a non-destructive fashion by providing information on the nanoparticles deposited on the sponge surfaces, both internal and external. Other deposited materials can be imaged in a similar manner providing they return a high enough contrast to the carbon microstructure, which is facilitated by the low atomic mass of carbon.

Hybrid graphene-metal oxide solution processed electron transport layers for large area high-performance organic photovoltaics.

Solution processed core-shell nano-structures of metal oxide-reduced graphene oxide (RGO) are used as improved electron transport layers (ETL), leading to an enhancement in photocurrent charge transport in PCDTBT:PC70 BM for both single cell and module photovoltaic devices. As a result, the power conversion efficiency for the devices with RGO-metal oxides for ETL increases 8% in single cells and 20% in module devices.

Triggered aggregation of PbS nanocrystal dispersions; towards directing the morphology of hybrid polymer films using a removable bilinker ligand.

Hybrid polymer films consist of quantum dots (QDs) dispersed in a polymer matrix. A key fundamental challenge that is hindering their optimisation in optoelectronic devices such as hybrid solar cells is overcoming uncontrolled aggregation of the QDs. In an effort to direct aggregation, and trigger self-assembly, we added a bilinker ligand (1,2-ethanedithiol) to dispersed PbS QDs in polymer solutions prior to film deposition by spin casting. Turbidity studies of the PbS QD/1,2-ethanedithiol dispersions enabled a relationship to be established between the extent of 1,2-ethanedithiol-triggered QD aggregation and the nominal fractional coverage of the QDs by 1,2-ethanedithiol. The extent of aggregation (and self-assembly) increased with nominal fraction coverage. Above a value of about 1.0 QD aggregation increased substantially. TEM images showed that at low 1,2-ethanedithiol concentrations triggered assembly of network-like QD structures occurred. At high 1,2-ethanedithiol concentrations the QDs self-assembled into more-ordered micrometre-sized crystals. The results suggest that 1,2-ethanedithiol decreases the inter-QD separation in dispersion as a result of rapid ligand exchange and this process results in QD aggregation as well as self-assembly. The assembled QD structures were successfully trapped within polymer films by spin casting of PbS QD/1,2-ethanedithiol dispersions containing added polystyrene or polytriarylamine.