Tuesday, July 16, 2013

Dye-Sensitized Solar Cells Achieve 15% Of Efficiency

EPFL, Switzerland, has achieved a new record of 15% efficiency for dye-sensitized solar cells (DSSCs). DSSCs have many advantages over their silicon-based counterparts. They offer transparency, low cost, and high power conversion efficiencies under cloudy and artificial light conditions. However, until now their overall efficiency has been lower than silicon-based solar cells, mostly because of the inherent voltage loss during manufacturing. Now, EPFL scientists have developed a new version of DSSC that is fabricated by a new two-step process raising their efficiency up to a record 15% without sacrificing stability.

The new DSSC uses a perovskite material as a light harvester and an organic hole transport material to replace the cell's electrolyte. Perovskite is a calcium titanium oxide mineral species. Typical fabrication of this new DSSC involves depositing a perovskite material directly onto a metal-oxide film. The problem is that adding the entire material together often causes wide variation in the morphology and the efficiency of the resulting solar cell, which makes it difficult to use them in everyday applications.

Michael Gr├Ątzel's team at EPFL has now solved the problem with a two-step approach: First, one part of the perovskite is deposited in to the pores of the metal-oxide scaffold. Second, the deposited part is exposed to a solution that contains the other component of the perovskite. When the two parts come into contact, they react instantaneously and convert into the complete light-sensitive pigment, permitting much better control over the morphology of the solar cell.

The new method raises DSSC power-conversion efficiency up to a record 15%, exceeding the power conversion efficiencies of conventional, amorphous silicon-based solar cells. The team believes that it will open a new era of DSSC development, featuring stability and efficiencies that equal or even surpass today's best thin-film photovoltaic devices.

Source: http://actu.epfl.ch/news/dye-sensitized-solar-cells-rival-conventional-ce-2/

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