Even if kesterite semiconductor conversion efficiency is not high, because the constituent elements are similar to CIGS solar energy, there will be no shortage of raw material supply, so this material is still considered as an alternative to CIGS solar cells. Helmholtz-Zentrum Berlin ( The HZB) team is dedicated to improving kesterite's solar energy application potential and analyzing the relationship between semiconductor composition and optoelectronic properties. In this study, the team replaced tin with germanium.
In order to further analyze the material, the team conducted a research at HZB's research reactor BER II, using neutron diffraction to detect samples, which can separate copper, zinc and thorium, allowing them to stay Within the crystal lattice.
The results show that high-efficiency kesterite solar cells usually contain less copper and more zinc, while at the same time they have the lowest point defect and copper-zinc misalignment. If more copper elements, the more easily the concentration point defects , And these are thought to make solar energy performance lower.
The research also further explored the energy band gap of kesterite samples. The lead author René Gunder said that the material energy gap is a characteristic of semiconductors. Different energy gaps can absorb different wavelengths of sunlight, which in turn affects the conductivity of materials. Solar energy conversion efficiency, and research pointed out that the base metal can increase the optical energy gap, so that the material can absorb more light, and increase solar cell conversion efficiency.
Research leader Professor Susan Schorr pointed out that the team believes that this type of kesterites semiconductors can be used not only for solar cells, but also for other applications such as photocatalysts, which use solar energy to decompose water into hydrogen and oxygen, and store solar energy in the form of chemical energy. This study has been published in the crystal engineering journal "CrystEngComm".