Solution-processed ultrafine gold nanowires (Au-NWs) have been exploited as plasmonic antennae in organic P3HT:PCBM photovoltaic cells. The careful reduction of the spacer layer thickness which allows the evanescent field to be extended into the photoactive layer and the geometry of the Au-NWs bands which favors the enhanced scattering collectively result in an increased short-circuit current density by 23.2%. The exact nature of the plasmonic effect in Au-NWs incorporated P3HT system and the critical role played by the spacer layer were studied through optical and time-resolved photoluminescence spectroscopy. The improved photocurrent in the Au-NWs integrated devices is due to an enhanced absorption in the photoactive layer which is contributed from an increased plasmon excitation field and far-field scattering of Au-NWs.
Efficiency enhancement in plasmonic bulk heterojunction (PCDTBT:PCBM) organic solar cells (OSCs) is demonstrated with the integration of large area periodic Ag nano-triangle (NT) arrays (that were fabricated using the cost-effective, high throughput nanosphere lithography technique) in the OSC device. The improvements to the power conversion efficiency (from 4.24% to 4.52%) and to the short circuit current density (by ~12%) are attributed to an increase in exciton generation induced by the strong local E-field and the scattering generated by the localized surface plasmon resonance of the hexagonal NT arrays. These findings are validated by a range of steady state and transient optical spectroscopy and correlated with device performance data. Importantly, our work demonstrates the feasibility of integrating a simple cost-effective, tailorable and scalable nanofabrication technique with existing OSC fabrication processes.
The
freshwater scarcity and increasing energy demand are
two challenging global issues. Herein, we propose a new route for
desalination, self-sustained visible-light-driven electrochemical
redox desalination. We propose a novel device architecture involving
internal integration of a quasi-solid-state dye-sensitized solar cell
and continuous redox-flow desalination units with a bifunctional platinized-graphite-paper
electrode. Both the solar cell and redox-flow desalination units are
integrated using the bifunctional electrode with one side facing the
solar cell operating as a positive electrode and the other side facing
the redox-flow desalination unit operating as a negative electrode.
The solar cell contains a gel-based tri-iodide/iodide redox couple
sandwiched between an N719 dye-modified photoanode and cathode. In
contrast, the redox-flow desalination consists of re-circulating ferro/ferricyanide
redox couple sandwiched between the anode and cathode with two salt
streams located between these electrodes. The performances of bifunctional
electrodes in both redox couples were thoroughly investigated by electrochemical
characterization. The brackish feed can be continuously desalted to
the freshwater level by utilizing visible light illumination. As a
device, this architecture combines energy conversion and water desalination.
This concept bypasses the need for electrical energy consumption for
desalination, which provides a novel structural design using photodesalination
to facilitate the development of self-sustained solar desalination
technologies.
Developing redox media as flow electrodes is a critical key in electrodialysis (ED) cells during the desalination process, enabling continuity, low cost and easy operation for freshwater production. Herein, we present viologen redox media as positive and negative flow electrodes in a continuous desalinated ED device. The viologen is reduced at the negative reservoir and oxidized at the positive side with blockage of ion exchange membranes, acting as a catalysis medium. The water product with 284 ppm can be extracted from the as-prepared 6000 ppm salt feed, and a salt removal efficiency of up to 95.3% is achieved. Cyclic voltammetry is performed to investigate the electrochemical behaviors of viologen. In addition, the desalination performance influence from the different current densities, cyclability, and various salt concentrations is further explored in detail. The current research will be significant to the further development of electrodialysis desalination technologies for freshwater production.
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