Cloudy day can also power - diffuse light solar cells
The solar cell -
Let's imagine the following scenario: no more recharge mobile phones, the kindle or tablets, isn't it?
Recently, some researchers say they have found a can use within buildings and cloudy days under the low intensity of diffuse light power generation solar cells, and the efficiency reaches a certain value.
This solar battery charging equipment, perhaps in the future will liberation equipment shell can be continuously to recharge, so don't need to insert the socket to charge.
Diffuse light solar cells is not a new thing, basic is very dependent on expensive semiconductor materials to achieve the best effect.
In 1991, the federal institute of technology in lausanne, Switzerland, the chemist MichaelGraetzel invented so-called dye sensitized solar cell (
, the battery can work to achieve the best effect in dim light, and cheaper than the standard solar cells.
In the sun, the best DSSCs are only 14% of the solar energy into electricity, while the standard of the solar cell conversion efficiency is 24%.
Is the major reason behind the light so fast, DSSCs is not timely transformation.
Therefore, when light energy at a slow pace according to it, such as low intensity light indoors, the conversion efficiency of DSSCs can increase to 28%.
DSSCs with standard silicon solar cell is a little different: standard silicon solar cells, absorb sunlight will an electron to a higher level of silicon atoms, so that they can skip the adjacent to the positive movement of atoms.
To collect and shunt electrons are the positive to the circuit, makes the circuit can work.
Leave electronic leaves a hole in the silicon atoms, hole is also can be moved, and accumulated over time, hole will flow to the cathode, the cathode and the external circuit, and electronic overlap in the solar cell silicon atomic charge balance again now, make its can continue to produce electricity.
The DSSCs clouding the electricity it to another level.
It still has a collection of positive and negative charge on the electrodes at both ends, but in the middle, no longer just pure silicon, but other materials, the typical material is titanium dioxide (
Titanium dioxide is not a good light absorption material, the researchers tried to particle surface coated with special light absorption materials & ndash;
Organic dye molecules.
Absorb the photons of the dye molecules that electrons and holes, stimulate the electronic transfer immediately to the titanium dioxide particles, through the titanium dioxide particles move to the anode.
At the same time, these holes is transferred to the electrolyte (
The cathode, and finally arrived.
Problems existing in the DSSCs is hole move slowly in the electrolyte, lead to holes tend to accumulate near the dyes and titanium dioxide particles, once excited electronic encountered a hole, it is both a hit, is produced by the heat energy instead of electricity.
In order to solve this problem, researchers have tried to use thin electrolyte layer, convenient cavity with the nearest distance to arrive at the destination.
Electrolyte thin layer, however, any defects can lead to short circuit device, a fatal blow at any time can make the solar cell to collapse.
Now, Graetzel and his colleagues have come up with another possible solution, they designed a kind of dye and hole conduction molecular assembly, tightly wrapped in titanium dioxide particles around again, so as to form a layer with no defect, fit closely, it solves the slow moving hole to go a long way to go to the cathode of the problem.
They 23, said in a report published in the journal Joule, the fixed layer will DSSCs of diffuse light conversion efficiency to 32% & ndash;
Close to the theoretical value.
Northwestern university chemist MichaelWasielewski said: & other;
This is a very good progress.
Although the new dye sensitization battery conversion efficiency is only 13 of the sun was shining.
1%, but he pointed out that, because of the diffuse light conversion efficiency increased by nearly 20%, therefore gives people planted to find new ways to improve the conversion efficiency under full sunlight of hope.