Kesterites are a promising PV material, it’s metal elements, Copper, Zinc, and Tin are abundant on earth crust. This material owns a tetragonal lattice similar to commercial PV technology. As Dr. Saucedo said, they come from the royal family of photovoltaics.
Kesterites comes from the royal family of photovoltaics
|Source: PV-Education Crystal structure of the royal family of photovoltaics|
The pace of research on kesterites has been slow due to the emergence of perovskites who has reached a conversion efficiency of 24%(early 2019) while kesterite holds a record of 12.6% reported by IBM in 2013. As you can see, there is a difference of 6 years between both reports .
STARCELL born to push forward kesterites PV technology and it is formed by universities and industrial partners. As you can see in the next image, the project is conceived by institutions which have the infrastructure for developing solar cells. You can read a complete description in the following link (About Starcell-Project)
|STARCELL organization structure for CZTS development of solar cells and scale-up to PV modules|
- Doping (intrinsic and extrinsic) with less than 1% of element incorporation
- Extrinsic: Incorporation of germanium (Ge) or sodium (Na)
- Intrinsic: Defect points like vacancies, substitution, or interstitials.
- Alloying with enough element incorporation where there is a change in the structure of the material.
Tips for crystallization and grain growth (Kesterites):
- After working with the sulfurization and selenization process, you would realize that selenium is noble and more controllable during heat treatment. You will love it.
- For the selenization process, he recommends a big annealing chamber, in this configuration, a homogeneous temperature at the center can be maintained. Therefore the process will keep reproducible.
- The graphite box for selenization reaction its a self-design developed at IREC, here we have proven several designs.
- The graphite box works well just ten consecutive times, but more than these tries selenium content runs out.