4. Conclusion
In summary, we have prepared CZTSe thin films on
Mo-coated glass substrates by selenization of co-electrodepositedelectrodeposited
Cu–Zn–Sn precursors. C6H8O7/Na3C6H5O7 was
adopted as complexing agent in the electrolyte to control
the cathodic potentials of Cu, Zn, and Sn cations and
reduce them at close potential. Two annealing processes,
rapid thermal annealing (RTA) and conventional furnace
annealing (CFA), were carried out for selenizing the precursors
at 500 C. It is found that the RTA process is conducive
to the formation of single phase CZTSe absorbers
with large grains. Possible mechanism was proposed based
on the XRD, Raman, SEM, and EDS results. The energy
band gap of the film is 0.98 eV and the optical absorption
coefficient is in the order of 104 cm1 in the visible region.
Finally, we have fabricated CZTSe solar cells with an efficiency
of 4.5% using the RTA–CZTSe absorbers. This
work demonstrates that a low-cost, non-vacuum process
using co-electrodeposition with subsequent RTA process
is a viable approach for the fabrication of CZTSe based
solar cells. Higher efficiency is expected when some part
of selenium is replaced by sulfur to increase its band gap.