The Dye Sensitized Solar Cells, also known as Grätzel cells, are a type of third generation solar cell that is low in cost, easy to manufacture and simpler to adjust in order to suit a large variety of applications. This was accomplished by using lower costing materials than the previous silicon based product as well as a simpler production process. Recent studies have shown that the Dye Sensitized Solar Cells can produce up to 11% efficiency and continued researched shows a possibility for it to become even more effective.
What is a DSSC?
Essentially, DSSC's are based on a wide bandgap semiconductor such as TiO2, that has been made highly receptive to light through the use of a layer of dye. The cell consists of four main parts including a photoelectrode composed of a transparent conducting oxide with a layer of TiO2 film, a counter electrode encompassing another transparent conducting oxide with a platinum catalyst deposited on it, a layer of dye that can be excited by light, and an electrolyte to fill in the voids of the inner cell.
How are they made?
The first step to manufacture a DSSC on glass it to prepare the photoelectrode. This is accomplished by taking a glass substrate coated with a transparent conducting oxide, such as SnO2:F, and depositing a layer of TiO2 through the process of screen printing using a firing furnace at about 500° C. This process will remove excess organic residue and create electrical contact. The photoelectrode is then submerged in a light sensitive dye. Simultaneously, a counterelectrode is prepared where another glass substrate coated in a transparent conducting oxide gets infused with a platinum catalyst. Next, the dyed photoelectrode is sealed to the counterelectrode using a thermoplastic thin film that is placed in between. These three components are then heated at about 150° C and placed under pressure. Once sealed, the voids in the device are filled with an electrolyte through holes in the counterelectrode. To ensure longevity, the cell's holes are filled and the whole cell is covered with glass.
(Information Provided by The Energy Research Centre of the Netherlands, Wikipeida and Dyesol)
The Korean Institute of Technology has introduced a new method that allows a solar cell to absorb more light, making it more efficient than its previous amount of 11%. This development was lead by researcher Park Nam-Gyu who claims that this new discovery will improve power consumption by at least 50% making it more efficient and even more cost effective than it was before.
Typically, a dye sensitized solar cell (DSSC) is a semiconductor that has been created from a photosensitized anode and an electrolyte. The cell is made of porous TiO2 particles that are covered with a specific dye that interacts with its respective electrolyte.
Nam-Gyu's team was able to improve this design by finding a way to have the TiO2 particles take in different colors of dyes that allow the cell to absorb a wider spectrum of light, which will, in turn, increase efficiency.
This was achieved by copying a scientific method of chromatography that involves separating chemical compound from mixtures. This process works in two phases, including the stationary phase and the mobile phase. In order to form the different layers, the team was able to control the release and settling of the dyes. As a result they were able to vertically align yellow, red and green dyes within the TiO2 film. This alignment was validated by an electron probe micro-analyzer.
It is expected that when the DSSC reaches a higher efficiency, they will become commercialized. This will cause a huge shift in the solar market from silicon based thick film solar cells into lighter dye sensitized solar cells that are expected to reach equivalent efficiencies at a significantly lower cost of production.
Next up is a more homely approach to solar cell usage.
(Information provided by PV-Tech)
