A team of engineers from Huazhong University of Science and Technology (China) has independently designed, built and tested tandem perovskite solar cells with record efficiency.
Their work was published in the journal .
These combine two materials to capture a wider spectrum of sunlight, thus increasing efficiency. They are usually made by combining a top layer of perovskite with a bottom layer of another material, such as silicon or another variant of perovskite.
Perovskite is a mineral consisting mainly of calcium titanate. Solar cell manufacturers are testing the use of perovskite as a replacement for silicon because it is cheaper, more efficient, easier to manufacture and allows solar cells to be made in irregular or even flexible configurations.
However, the use of perovskite in commercial applications has been limited due to difficulties in producing defect-free panel surfaces, which lead to non-radiative energy losses, thus reducing cell efficiency. In this new study, the research team found a way to create cells using this material with far fewer defects, resulting in record efficiency, .
Chinese researchers have created tandem solar cells from perovskite
Researchers have developed a surface reconstruction technique that reduces defects in the top perovskite layer. This technique uses BDA and EDAI2 to modify (polish) the cell surface.
The team was able to obtain a mixed Sn–Pb perovskite film with fewer defects than those made by . This enabled improvements in the transport of charge carriers and reduced energy losses at the transport layer.
To test the new technique, the researchers created and polished a top layer, which served as a light-absorbing layer. This was then placed over an electron transfer layer made of C60, with a hole transport layer made of PEDOT:PSS. Finally, they added .
Tests showed the cell to have a power conversion efficiency of 28.49%, which was independently verified. They also noted that the cell demonstrated durability, continuing to perform optimally after 550 hours of continuous operation.
