Cu(Zn,Sn)(S,Se)2 (CZTS) is a potential candidate for absorber layers
in solar cells because of their attractive properties such as high
absorption coefficient of over 104, non-toxicity, earth abundant,
and suitable band gap of 1–1.63 eV for getting high efficiency
. CZTS had been reported, for the first time, about photovoltaic
applications in solar cell field in the late 1980s. The conversion
efficiency of CZTS solar cells has been significantly improved in the
recent years, hence, it has received a lot of interests from
researchers around the world recently. The CZTS films can be fabricated
by vacuum methods, e.g. evaporation and sputtering, or by
non-vacuum method such as spray pyrolysis and printing.
The CZTS solar cells fabricated by vacuum method have shown a
lower efficiency than that of non-vacuum methods. Among
non-vacuum methods, printing is quite useful because it is simple,
low cost, high-speed manufacture, and can prepare large-scale
samples. Guo reports a record efficiency of 7.2% for CZTSSe solar
cells using printing method without using highly toxic materials.
Up to now, the highest efficiency of CZTS solar cells using spincoating
method is 12.6%. However, highly toxic hydrazine was
used for fabricating devices. For the mentioned reasons, the printing
method is chosen to fabricate CZTS films in our research.