Chinese researchers fabricated a kesteritic PV device using a transparent fluorine-doped tin oxide (FTO) substrate instead of substrates based on opaque Mo-coated soda lime glass. The breakdown voltage of the cell is 0.522 V, the short circuit current is 33.0 mA cm−2 and the fill factor is 68.55%.
Kesterite is one of the most promising light-attenuating materials for potential use in low-cost thin-film solar cells. Kesterites contain common elements such as copper, tin, zinc and selenium. Unlike CIGS compounds, supply bottlenecks are not expected in the future.
However, kesterite is still less efficient than CIGS in mass production. The world record for such cells is 12.6%, achieved by Japanese thin film producer Solar Frontier in 2013.
“Our keno could be used in building-integrated solar PV (BIPV) and agricultural electricity, as well as solar windows and facades,” researcher Hao Xin said. pv magazine.
The researchers built the cell using a transparent fluorine-doped tin oxide (FTO) substrate coated with molybdenum (Mo) instead of commonly used substrates opaque Mo-coated soda-lime glass. They also added amolybdenum trioxide (MoO3) a layer between the FTO and the precursor film to prevent grain overgrowth on the absorption surface.
In addition, researchers relied on sodium (Na) doping and silver (Ag) doping to facilitate grain growth. They broke up absorbing compound in dimethyl sulfoxide (DMSO) solution.
“The solution was spin-coated onto an FTO substrate to form a precursor film, which was further annealed with selenium in a furnace tube to form the CZTSSe absorbent,” the researchers explained. “A cadmium sulfide (CdS) buffer layer was then deposited on the CZTSSe by chemical bath deposition.
Academics too set the window layer with native zinc oxide (i-ZnO) and indium tin oxide (ITO) sputtertering. They perfected the manufacturing process by thermally evaporating nickel (Ni) and aluminum (Al). upper electrodes.
Under normal lighting conditions, a cell whose active region is 0.103 cm2 and an anti-reflective coating based on magnesium fluoride (MgF2) achieved a power conversion efficiency of 11.43% and a breakdown voltage of 0.522 V. Its short-circuit current 33.0 mA cm−2 and fill factor 68.55%. China’s national PV Area Measurement and Testing Center at Fujian Metrology Insttute (FJL) confirmed the results.
“High efficiency and easy solution process of kesterite solar cells the transparent electrodes reported here open the door to this Green and affordable thin film technology for many advanced applications such as semi-transparent, bifacial and tandem solar cells,” the researchers concluded.
The researchers presented the cell technology in “11.4% Efficiency Kesterite Solar Cells on Transparent Electrode,” published recently Advanced energy materials. “So far we have not estimated the production costs of the cells, but we are sure that the raw materials used to make the cells themselves are very cheap,” they said.