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[摘要]：Cu(2)Zn(Sn(1-x)Ge(x))S(4) nanocrystals have been synthesized via batch reaction in oleylamine with no additional surfactants present. The nanocrystals are knife-coated on molybdenum substrates and then selenized to form a dense layer of Cu(2)Zn(Sn(1-x)Ge(x))-(S,Se)(4), which is then used as the photoabsorbing layer in a thin film solar cell. The band gaps of the nanocrystals and the resulting solar cells are demonstrated to be controlled by adjusting the Ge/(Ge+Sn) ratio of the nanocrystal synthesis precursors. Solar cells fabricated from Cu(2)ZnGeS(4) nanocrystal films yielded a power conversion efficiency of 0.51%. However, Cu(2)Zn (Sn(x)Ge(1-x))S(4) nanocrystals with a Ge/(Ge+Sn) ratio 0.7 yielded devices with an efficiency of 6.8% when synthesized to be Cu-poor and Zn-rich. This result opens the possibility of forming Ge gradients to direct minority carriers away from high recombination interfaces and significantly improve the device efficiency of CZTSSe-based solar cells. |
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