Analysis of Effect of Zn(O,S) Buffer Layer Properties on CZTS Solar Cell Performance Using AMPS

The Cu2ZnSnS4（CZTS）-based solar cell is numerically simulated by a one-dimensional solar cell simulation software analysis of microelectronic and photonic structures（AMPS-ID）.The device structure used in the simulation is Al/ZnO:Al/nZn（O,S）/pCZTS/Mo.The primary motivation of this simulation work is to optimize the composition in the ZnO1-xSx buffer layer,which would yield higher conversion efRciency.By varying S/（S+0） ratio x,the conduction band offset（CBO） at CZTS/Zn（0,S） interface can range from-0.23 eV to 1.06 eV if the full range of the ratio is considered.The optimal CBO of 0.23 eV can be achieved when the ZnO1-xSx buffer has an S/（S+0） ratio of 0.6.The solar cell efRciency Rrst increases with increasing sulfur content and then decreases abruptly for x > 0.6,which reaches the highest value of 17.55%by our proposed optimal sulfur content x = 0.6.Our results provide guidance in dealing with the ZnO1-xSx buffer layer deposition for high efficiency CZTS solar cells.