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32%! The Charging Efficiency Of The Diffuse Light Solar Battery Is Record
- Apr 27, 2018 -


32%! The charging efficiency of the diffuse light solar battery is record


       The researchers report that the solar cells they developed can make use of low intensity diffuse light that exists inside the building and outside the sky, and the work efficiency is record. These batteries can produce devices that can continuously charge some gadgets without plugging in the power supply one day.


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      Imagine that you never need to recharge your mobile phone, e-reader or tablet computer anymore. The researchers report that the solar cells they developed can make use of low intensity diffuse light that exists inside the building and outside the sky, and the work efficiency is record. These batteries can produce devices that can continuously charge some gadgets without plugging in the power supply one day.


      Diffuse light solar cells are not new, but the best batteries depend on expensive semiconductors. In 1991, Michael Graetzel, a chemist at the Swiss Confederation Polytechnic Institute, invented the so-called dye-sensitized solar cell (DSSC). It performs best in dim light and is cheaper than standard semiconductor modules. However, under sunny conditions, the best DSSC can only convert 14% of the solar energy into electricity, while the standard solar cell can reach about 24%. This is mainly because the energy comes so fast that DSSC can't handle it. When energy comes at a slower speed, such as low intensity indoor light, Graetzel's DSSC can convert 28% of its light energy into electricity.


      DSSC still has two electrodes that collect negative and positive charges. But in the middle, they have different electronic conductors, usually of titanium dioxide (TiO2), rather than silicon. However, TiO2 is a very weak light absorbent. For this reason, researchers have applied organic dye molecules that can be used as super light absorbers on the surface of these particles. The absorbed photons stimulate electrons and holes in these dye molecules, just like in silicon. The dye immediately transfers the excited electrons to the TiO2 particles, and electrons move along them to the cathode. At the same time, the hole was dumped into a conductive liquid called electrolyte. There they continue to penetrate and enter negatively charged electrodes.


       The problem with DSSC is that the hole can not pass through the electrolyte very quickly. Therefore, they often accumulate near dyes and TiO2 particles. If the excited electrons eventually crash into holes, they will merge to generate heat instead of electricity.


       To solve this problem, the researchers try to thin the electrolyte, so that the hole does not need to travel far enough to reach the destination. However, any defects in these thin layers will cause the equipment to be dealt a fatal blow and destroy the entire solar cell. Now, Graetzel and his colleagues have proposed a possible solution. They designed a combination of dye and hole conducting molecules. It can wrap itself tightly around the TiO2 particles and create a tight layer without defects. This means that the distance of slow moving holes is smaller before reaching the negative pole. The researchers reported in Joule magazine that the tightlayer increased the diffuse light efficiency of DSSC to 32% - near the theoretical maximum.



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