posted on 2024-01-31, 05:04authored byHaixuan Gao, Chuanhe Ma, Jinhui Zhang, Jinchun Jiang, Ye Chen, Lin Sun, Hailong Wang
In
the prior art of CZTSSe solar cells, the traditional cadmium
salt (Cd-salt) CdSO4 is widely considered as a common raw
material for preparing CdS buffer layers. However, in this study,
we systematically demonstrated the phase structure and transmission
spectra improvement effect of the other three types of Cd-salts, Cd(NO3)2, CdCl2, and CdAc2, on
the CZTSSe/CdS heterojunction (HJT) compared to CdSO4.
CZTSSe/CdS HJT prepared by Cd(NO3)2 showed the
strongest CdS phonon characteristic peaks at 295.9 and 597.6 cm–1, indicating a pure crystal phase. The transmittance
of CdS films prepared by Cd(NO3)2 is 20–35%
higher than the other three Cd-salts in the light range of 350–1000
nm, which effectively improved the band gap of the films (2.41 eV)
and depressed the photon absorption and scattering. Accordingly, CZTSSe
solar cells based on the aforementioned Cd-salts showed that Cd(NO3)2 possessed the best ability to improve the photovoltaic
conversion efficiency (PCE), about 5.7% more than the traditional
CdSO4 salt. After Sn2+ replaced by Sn4+ in the precursor solution, the PCE of CZTSSe solar cells using Cd(NO3)2 exceeded 10% (Total area = 0.21 cm2, PCE = 10.23%, VOC = 0.485 V, JSC = 31.4 mA/cm2, FF = 67.1%, without MgF2 antireflective layer).