ABSTRACT
The aim of this study was to investigate the effect of gold nanoparticle (Au NP)-induced surface plasmons on the performance of organic photovoltaics (OPVs) that consist of copper phthalocyanine and fullerene as the active materials. The photon absorption can be enhanced by immobilization of surfactant-stabilized Au NPs on a self-assembled monolayer-modified indium tin oxide (ITO) electrode, and thus, the photocurrent as well as the power conversion efficiency (PCE) of these OPVs can be improved. Varying the density of the immobilized Au NPs in the devices provided no significant variation in the charge mobility but it did enhance the photocurrent. In addition, device simulation results demonstrated that the improvement in photocurrent was due to the enhancement of light absorption and the increase in charge separation, which was facilitated by the Au NPs. Overall, we attributed the improvement in PCE of OPVs to a localized surface plasmon resonance effect generated by the Au NPs.
ABSTRACT
In this paper a simple and highly sensitive electroanalytical method for the determination of caffeine content using 1,4-benzoquinone modified carbon paste electrode is presented. The method is based on suppression of 1,4-benzoquinone peak current on addition of caffeine. Square-wave and cyclic voltammetric techniques were utilised for the investigation. The 1,4-benzoquinone modified electrode exhibited a well-defined peak with reproducible peak current values for repetitive measurements; and showed a decrease in peak current value with an increase in caffeine content. The result revealed two linear range regions between 0 mmol L(-1) and 0.5 mmol L(-1) and 0.5 mmol L(-1) and 8.0 mmol L(-1), with detection limits of 0.3 micromol L(-1) and 5.1 micromol L(-1), respectively. The method was then successfully applied to the determination of caffeine content in coffee samples. The effects of pH, electrode composition, step potential, pulse amplitude and square-wave frequency on the voltammetric responses were also investigated.
