Chinese researchers claim to have measured the selenization annealing process of kesterite solar cells to produce a kesterite absorber with few defects. They have developed a device with a certified efficiency of 13.8%.
“Considering the advantages of low cost, high material stability, tunable bandgap, and high industrial compatibility of CZTSSe solar cells, we believe that this solar cell has promising commercialization potential, such as BIPV and other suitable applications,” researcher Dongmei Li said. pv magazine.
The researchers explained that selenization annealing is a key process in the development of highly efficient kesterite solar cells. At this stage, tin(II) sulfide (SnS) is usually added, but an excessive presence can cause defects in the CZTSSe absorber.
They also claim to have regulated the kinetic process of phase evolution by tailoring the positive chamber pressure lowers the selenium (Se) partial pressure.
“The collision probability between the precursor and the gaseous selenium molecule can be reduced during the heating step (200 C to 400 C) of the selenium reaction,” they explained, noting that this has contributed to a reduction in bulk errors by about one order of magnitude.
The research team built a kesterite cell with an interface layer made of molybdenum (Mo), a kesterite absorber, cadmium sulfide (CdS) buffer layer, window layer zinc oxide (ZnO) and indium tin oxide (ITO) substrate. They completed the manufacturing process with thermal evaporation of nickel (Ni) and aluminum (Al) top electrodes and an anti-reflective coating based on magnesium fluoride (MgF2).
The power conversion efficiency of the device is 14.13%, open circuit voltage 551.20 mV, short circuit current 35.74 mA cm−2 and fill factor 71.73%. They also internally certify the cell efficiency as 13.8%.
“The highly efficient kesterite solar cell also shows excellent long-term stability in the prevailing environment without encapsulation,” the researchers stated.
The team presented the cell technology in the paper “Controlling kesterite phase evolution by controlling selenium partial pressure in solar cells with 13.8% certified efficiency,” published recently Energy of nature.
“This work provides a kinetic control strategy better understanding and regulation of the phase evolution process with kesterite, especially by optimizing the phase evolution path highly efficient kesterite solar cells,” the researchers said.
Kesterite is one of the most promising light-attenuating materials for potential use in low-cost thin-film solar cells.
