Solution processed graphene–silicon Schottky junction solar cells

Here, surfactant-assisted exfoliated graphene (SAEG) has been used to make transparent conducting graphene films which for the first time were used to make SAEG–silicon Schottky junctions for photovoltaics. The graphene films were characterised using UV-Vis spectroscopy, Raman spectroscopy, atomic force microscopy and four point probe sheet resistance measurements. The effects of film thickness, thermal annealing and chemical doping of the graphene films on the power conversion efficiency (PCE) of the cells were investigated. Mild annealing of thickness optimised films resulted in a doubling of the PCE. Additionally, chemical doping resulted in a further 300% increase of the peak PCE. These results indicate that SAEG has the potential to compete with chemical vapour deposited graphene in graphene–silicon Schottky junction applications.This work was supported by the Australian Microscopy and Microanalysis Research Facility (AMMRF). This work was also performed in part at the Flinders University node of the Australian National Fabrication Facility, a company established under the National Collaborative Research Infrastructure Strategy to provide nano- and micro-fabrication facilities for Australia's researchers

Heterojunction solar cells based on silicon and composite films of graphene oxide and carbon nanotubes

Graphene oxide (GO) sheets have been used as the surfactant to disperse single-walled carbon nanotubes (CNT) in water to prepare GO/CNT electrodes that are applied to silicon to form a heterojunction that can be used in solar cells. GO/CNT films with different ratios of the two components and with various thicknesses have been used as semitransparent electrodes, and the influence of both factors on the performance of the solar cell has been studied. The degradation rate of the GO/CNT-silicon devices under ambient conditions has also been explored. The influence of the film thickness on the device performance is related to the interplay of two competing factors, namely, sheet resistance and transmittance. CNTs help to improve the conductivity of the GO/CNT film, and GO is able to protect the silicon from oxidation in the atmosphere.This work is supported by the Australian Microscopy and Microanalysis Research Facility (AMMRF). We thank Professor Amanda Ellis (Flinders University, South Australia) for providing the GO

Preparation and characterization of multiwalled carbon nanotube (MWCNT)/polymer nanostructured materials

http://spiedigitallibrary.org/journals/doc/SPIEDL-home/proc

Preparation and characterisation of vertically aligned single-walled carbon nanotube arrays on porous silicon

http://spiedigitallibrary.org/journals/doc/SPIEDL-home/proc

Field emission from single-, double-, and multi-walled carbon nanotubes chemically attached to silicon

The chemical attachment and field emission (FE) properties of single-walled carbon nanotubes (SWCNTs), double-walled carbon nanotubes (DWCNTs), and multi-walled carbon nanotubes (MWCNTs) chemically attached to a silicon substrate have been investigated. A high density of CNTs was revealed by atomic force microscopy imaging with orientation varying with CNT type. Raman spectroscopy was used to confirm the CNT type and diameter on the surfaces. The field emission properties of the surfaces were studied and both current-voltage and Fowler-Nordheim plots were obtained. The SWCNTs exhibited superior FE characteristics with a turn-on voltage (Eto) of 1.28 V μm−1 and electric field enhancement factor (β) of 5587. The DWCNT surface showed an Eto of 1.91 V μm−1 and a β of 4748, whereas the MWCNT surface exhibited an Eto of 2.79 V μm−1 and a β of 3069. The emission stability of each CNT type was investigated and it was found that SWCNTs produced the most stable emission. The differences between the FE characteristics and stability are explained in terms of the CNT diameter, vertical alignment, and crystallinity. The findings suggest that strength of substrate adhesion and CNT crystallinity play a major role in FE stability. Comparisons to other FE studies are made and the potential for device application is discussed

Water transport through nanoporous materials: Porous silicon and single walled carbon nanotubes

We report upon the pressure driven water transport through porous silicon (pSi) and single walled carbon nanotube (SWCNT) membranes. Fabrication of the membranes was monitored by AFM and SEM. Water permeability as high as 16926 mm3 cm-2 s-1 atm-1 is found for the pSi membrane. The SWCNT membrane is built upon the pSi membrane and a water permeability of 0.02 mm3 cm-2 s-1 atm-1 is achieved. Performance comparisons to similar CNT membranes are made and future improvements to the system are proposed

Plasma enhanced vortex fluidic device manipulation of graphene oxide

Open Access Article. This article is licensed under a Creative Commons Attribution 3.0 Unported Licence.A vortex fluid device (VFD) with non-thermal plasma liquid processing within dynamic thin films has been developed. This plasma–liquid microfluidic platform facilitates chemical processing which is demonstrated through the manipulation of the morphology and chemical character of colloidal graphene oxide in water

Estimating Site Performance (ESP) : can trial managers predict recruitment success at trial sites? An exploratory study

Availability of data and materials All quantitative data generated and analysed during this study are included in this published article [and its supplementary information files] Additional file 3. The dataset of predictions used and analysed during the current study are available from the corresponding author on reasonable request. The transcript of the group discussion generated and analysed during the current study is not publicly available due it containing information that could compromise research participant consent (it would be a relatively simple matter to identify trials and trial managers) but are available from the corresponding author on reasonable request.Peer reviewedPublisher PD

Measuring the Density of States of the Inner and Outer Wall of Double-Walled Carbon Nanotubes

This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).The combination of ultraviolet photoelectron spectroscopy and metastable helium induced electron spectroscopy is used to determine the density of states of the inner and outer coaxial carbon nanotubes. Ultraviolet photoelectron spectroscopy typically measures the density of states across the entire carbon nanotube, while metastable helium induced electron spectroscopy measures the density of states of the outermost layer alone. The use of double-walled carbon nanotubes in electronic devices allows for the outer wall to be functionalised whilst the inner wall remains defect free and the density of states is kept intact for electron transport. Separating the information of the inner and outer walls enables development of double-walled carbon nanotubes to be independent, such that the charge transport of the inner wall is maintained and confirmed whilst the outer wall is modified for functional purposes.This research received no external funding

Efficiency Improvement Using Molybdenum Disulphide Interlayers in Single-Wall Carbon Nanotube/Silicon Solar Cells

This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).Molybdenum disulphide (MoS2) is one of the most studied and widely applied nanomaterials from the layered transition-metal dichalcogenides (TMDs) semiconductor family. MoS2 has a large carrier diffusion length and a high carrier mobility. Combining a layered structure of single-wall carbon nanotube (SWCNT) and MoS2 with n-type silicon (n-Si) provided novel SWCNT/n-Si photovoltaic devices. The solar cell has a layered structure with Si covered first by a thin layer of MoS2 flakes and then a SWCNT film. The films were examined using scanning electron microscopy, atomic force microscopy and Raman spectroscopy. The MoS2 flake thickness ranged from 5 to 90 nm while the nanosheet’s lateral dimensions size ranged up to 1 μm2. This insertion of MoS2 improved the photoconversion efficiency (PCE) of the SWCNT/n-Si solar cells by approximately a factor of 2The support of the Australian Research Council Discovery Program (DP150101354 and DP160101301) is gratefully acknowledged