Recent research has made dye-sensitized solar cells more efficient. Image credit: ROLAND HERZOG, EPFL
Imagine never having to recharge your cell phone, e-reader or tablet. Researchers report that the solar cells they developed could use low-intensity diffuse light that is present inside buildings and outdoors on cloudy days, and the efficiency of work can be achieved. Records. These batteries may one day give birth to a device housing that can continue to charge some gadgets without plugging in.
Diffuse light solar cells are not new, but the best batteries rely on expensive semiconductors. In 1991, the Swiss Federal Institute of Technology chemist Michael Graetzel invented the so-called dye-sensitized solar cell (DSSC). Its performance in dim light Best, and cheaper than standard semiconductor components. However, in sunny conditions, the best DSSC can only convert 14% of sunlight's energy into electricity, and standard solar cells can reach about 24%. It's mainly because the energy comes so fast that DSSC can't handle it. When energy comes at a slower speed, such as in low-intensity room lighting, Graetzel's DSSC can convert 28% of its absorbed light into electricity.
The DSSC still has two electrodes that collect negative and positive charges. But in the middle, they have a different electron conductor, usually a collection of titanium dioxide (TiO2) particles, not just silicon. However, TiO2 is a very weak Light Absorbers. To this end, the researchers coated these particles with an organic dye molecule that acts as a superabsorbent. The absorbed photons excite electrons and holes on these dye molecules, just like in silicon. The dye immediately transfers the excited electrons to the TiO2 particles, and the electrons move quickly along them to the positive electrode. At the same time, the holes are dumped into a conductive liquid called an electrolyte. There, they continue to Infiltrate and enter negatively charged electrodes.
The problem with DSSC is that cavities cannot pass through the electrolyte very quickly. Therefore, they often accumulate near the dye and TiO2 particles. If the excited electrons eventually crash into the cavities, they merge, generating heat instead of electricity.
To solve this problem, the researchers tried to make the electrolyte thin so that the holes could travel to the destination without going too far. However, any defects in these layers would cause the device to be fatal and destroy it. The entire solar cell. Now, Graetzel and colleagues proposed a possible solution. They designed a combination of a dye and a hole-conducting molecule. It enables it to wrap tightly around TiO2 particles, creating no defects. The tight layer. This means that the slow moving hole travels less before reaching the negative electrode. The researchers reported in the Joule magazine that the tight layer increases the diffuse light efficiency of the DSSC to 32%—nearly theoretically. The maximum value.
