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Integrating a Triplet-triplet Annihilation Up-conversion System to Enhance Dye-sensitized Solar Cell Response to Sub-bandgap Light

The poor response of dye-sensitized solar cells (DSCs) to red and infrared light is a significant impediment to the realization of higher photocurrents ...

The University of Wollongong

Highly crystalline NiO nanoparticles synthesized through a facile thermolysis route were used as photocathode materials in p-type dye-sensitized solar cells resulting in open-circuit voltages exceeding 300 mV with an iodide/triiodide mediator.

Enhanced open-circuit voltage of p-type DSC with highly crystalline NiO nanoparticles.

A one-pot synthesis of 2,6-dibromodithieno[3,2-b;2',3'-d]thiophene (dibromo-DTT, 4) was developed. A key step was bromodecarboxylation of DTT-2,6-dicarboxylic acid, obtained by saponification of the diester 1. The donor-acceptor dye DAHTDTT (13), based on a central 2,6-bis[2'-(3'-hexylthienyl)]dithieno[3,2-b;2',3'-d]thiophene core (9), was prepared and incorporated in a dye-sensitized solar cell (DSC), which exhibited an energy conversion efficiency of 7.3% with V(oc) of 697 mV, J(sc) of 14.4 mA/cm(2), and ff of 0.73 at 1 sun.

Dithienothiophene (DTT)-based dyes for dye-sensitized solar cells: synthesis of 2,6-dibromo-DTT.

To date, nickel(II) oxide (NiO) is one of the few p-type semiconductors that has successfully been used for the construction of dye-sensitized photocathodes as well as tandem dye-sensitized solar cells. In this study we present a novel fabrication method for the preparation of mesoporous NiO films based on preformed NiO nanopowders. Critical properties such as pore-size distribution, crystallinity, and internal surface area of the resulting NiO films were controlled through the sintering process and optimized for their application as dye-sensitized photocathodes, resulting in a significantly increased photovoltaic performance, compared to earlier studies. A series of different sensitizers and electrolytes was scrutinized for their application in dye-sensitized NiO photocathodes. Despite its limited absorption range the dye coumarin 343 clearly outperforms other sensitizers used in this study. Values for short-circuit current densities of 2.13 mA cm(-2) and overall energy conversion efficiencies of 0.033% under simulated sunlight (AM1.5, 1000 W m(-2)) are the highest values reported in literature so far.

Dye-sensitized nickel(II)oxide photocathodes for tandem solar cell applications.

By controlling the SWNT-rGO electrode composition and thickness to attain the appropriate porosity and tortuosity, the electroactive surface area is maximized while rapid diffusion of the electrolyte through the electrode is maintained. This leads to an increase in exchange current density between the electrode and electrolyte which results in enhanced thermocell performance.

Carbon nanotube - reduced graphene oxide composites for thermal energy harvesting applications.

Enhanced photocatalytic degradation of methylene blue (MB) using graphitic carbon nitride/titanium dioxide (g-C3N4/TiO2) catalyst films has been demonstrated in this present work. The g-C3N4/TiO2 composites were prepared by directly heating the mixture of melamine and pre-synthesized TiO2 nanoparticles in Ar gas flow. The g-C3N4 contents in the g-C3N4/TiO2 composites were varied as 0, 20, 50 and 70 wt%. It was found that the visible-light-induced photocatalytic degradation of MB was remarkably increased upon coupling TiO2 with g-C3N4 and the best degradation performance of ~70% was obtained from 50 wt% g-C3N4 loading content. Results from UV-vis absorption study, Electron microscopy, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy suggest that the improved photoactivity is due to a decrease in band gap energy, an increased light absorption in visible light region and possibly an enhanced electron-hole separation efficiency as a result of effective interfacial electron transfer between TiO2 and g-C3N4 of the g-C3N4/TiO2 composite film. Based on the obtained results, the possible MB degradation mechanism is ascribed mainly to the generation of active species induced by the photogenerated electrons.

Enhanced visible-light photocatalytic activity of g-C3N4/TiO2 films.

Three-dimensional (3D) hierarchical nanoscale architectures comprised of building blocks, with specifically engineered morphologies, are expected to play important roles in the fabrication of 'next generation' microelectronic and optoelectronic devices due to their high surface-to-volume ratio as well as opto-electronic properties. Herein, a series of well-defined 3D hierarchical rutile TiO2 architectures (HRT) were successfully prepared using a facile hydrothermal method without any surfactant or template, simply by changing the concentration of hydrochloric acid used in the synthesis. The production of these materials provides, to the best of our knowledge, the first identified example of a ledgewise growth mechanism in a rutile TiO2 structure. Also for the first time, a Dye-sensitized Solar Cell (DSC) combining a HRT is reported in conjunction with a high-extinction-coefficient metal-free organic sensitizer (D149), achieving a conversion efficiency of 5.5%, which is superior to ones employing P25 (4.5%), comparable to state-of-the-art commercial transparent titania anatase paste (5.8%). Further to this, an overall conversion efficiency 8.6% was achieved when HRT was used as the light scattering layer, a considerable improvement over the commercial transparent/reflector titania anatase paste (7.6%), a significantly smaller gap in performance than has been seen previously.

Article	Year
Enhanced open-circuit voltage of p-type DSC with highly crystalline NiO nanoparticles. Chemical communications (Cambridge, England)\| PubMed ID: 21416106	2011
Dithienothiophene (DTT)-based dyes for dye-sensitized solar cells: synthesis of 2,6-dibromo-DTT. The Journal of organic chemistry\| PubMed ID: 21486091	2011
Dye-sensitized nickel(II)oxide photocathodes for tandem solar cell applications. Nanotechnology\| PubMed ID: 21730603	2008
Carbon nanotube - reduced graphene oxide composites for thermal energy harvesting applications. Advanced materials (Deerfield Beach, Fla.)\| PubMed ID: 24167027	2013
Enhanced visible-light photocatalytic activity of g-C3N4/TiO2 films. Journal of colloid and interface science\| PubMed ID: 24407703	2014
3D Hierarchical Rutile TiO2 and Metal-free Organic Sensitizer Producing Dye-sensitized Solar Cells 8.6% Conversion Efficiency. Scientific reports\| PubMed ID: 25167837	2014

Andrew Nattestad

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