Copper phenanthroline complexes in the solid phase can act as efficient molecular hole transporting material (HTM) for hybrid solar cells. We prepared solid-state dye-sensitized solar cells with the organic dye LEG4 and bis(2,9-dimethyl-1,10-phenanthroline)copper(I/II) (Cu(dmp)2) and achieved power conversion efficiencies of more than 8% under 1000 W m−2 AM1.5G illumination, with open-circuit potentials of more than 1.0 V. The successful application of a copper-complex based HTM paves the way for low-cost and efficient hybrid solar cells, as well as for other opto-electronic devices. Credit: Marina Freitag et al. “High-efficiency dye-sensitized solar cells with molecular copper phenanthroline as solid hole conductor,” Energy Environ. Sci. (2015). DOI: 10.1039/C5EE01204J
A group of researchers at Uppsala University has discovered a “zombie solar cell” that continues to generate electricity with unexpected effectiveness although the liquid transferring charges between the electrodes has dried out.
When the researchers tested old dye-sensitized solar cells, also known as Grätzel cells, these were still active, despite the fact that the electrolyte conducting electricity between the minus and plus poles had evaporated. “The dried-out solar cells worked in some cases even better than when they were liquid-filled and alive. The power conversion efficiency of specific cells had increased to 8%, which is a record for dye-sensitized solar cells with a solid hole conductor.
In a Grätzel cell, an electrically conductive liquid facilitates a flow of electrons with the use of substances that can give away or take up electrons, ie redox couple. But when this liquid dried out in “zombie solar cell”, a solid hole conducting structure was created, continuing to transport positive charge. However, this only occurs with certain copper based redox couples.
The advantage of a solar cell without liquid is that it hopefully becomes more stable. When the solar cell is in a solid state, it is much easier and cheaper to seal. This reduces the risk for the cell to leak and corrode the surrounding material. “We also need to test the cells in the sunlight for a long period of time to see if they work in the long run.”
“The final purpose is of course energy production in the form of solar cells on the roof. We know this works for solid state photovoltaics. Grätzel solar cells work very well even if the light source is not optimal – you can acquire kilowatt hours even if it’s cloudy.”
“To get there is however a long road, it takes a lot more research. But if we can make these ‘zombie solar cells’ very affordable, you can imagine them almost anywhere, for example charging mobiles or running computers.”
http://phys.org/news/2015-10-zombie-solar-cells-power-electrolyte.htmljCp
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