Chinese scientists have developed a new method for growing titanium dioxide nanorods, which makes it possible to precisely control the distance between the rods without changing their size. This makes solar cells more efficient: they absorb light better and transfer electric charge more reliably.
The study was led by Professor Mingtai Wang from the Hefei Institute of Physical Sciences of the Chinese Academy of Sciences. His team has found a way to create structures from TiO₂ nanorods in which the distance between the rods can be changed, while their height and diameter remain constant. The scientists have successfully applied this technology in next-generation solar cells.
Titanium dioxide nanorods absorb light and transfer electric charge very well, which is why they are widely used in solar panels, photocatalysts and sensors. However, it used to be difficult to adjust the density of the rods during their production: changing one parameter, like the diameter, would affect the others, preventing the achievement of maximum efficiency.
The scientists created conditions in which these chains formed small crystals of anatase, a form of titanium dioxide. After this, they subjected it to heat treatment, transforming the anatase into rutile. They used rutile crystals as a building block, setting the direction and structure of nanorod growth. Thanks to this, they were able to precisely control the density of the rods without changing their size.
The TiO₂-NA films created as a result were used in solar cells based on copper-indium-disulfide (CuInS₂), demonstrating excellent results: their efficiency reached 10.44%. In order to explain why the distance between rods is so important, the Chinese researchers developed a model showing how density affects the absorption of light, the separation of electrical charges and their movement inside the device.
The study clearly demonstrated how precise control of the microstructure of materials can improve the performance of solar cells.
