电沉积合金预制层后退火制备铜锌锡硫薄膜及其光伏特性

Preparation and photovoltaic characterization of Cu_2ZnSnS_4 thin films fabricated by electrodeposition of alloy precursor followed by annealling

采用电沉积铜锌锡(Cu-Zn-Sn,CZT)合金预制层后退火制备薄膜太阳电池用吸收层材料铜锌锡硫(Cu_2ZnSnS_4,CZTS)。利用扫描电镜、X线能量色散谱仪、X线衍射仪、拉曼光谱等检测方法对不同预制层成分下制备的CZTS薄膜的表面形貌、成分和物相结构进行表征与分析。研究结果表明:随着预制层中铜摩尔分数的增加,CZTS薄膜(112)面衍射峰半峰宽呈现先减小后增大的趋势,在物质的量比n(Cu)/n(Zn+Sn)=0.83和n(Zn)/n(Sn)=1.31的条件下获得半峰宽最小、结晶性能最好的CZTS薄膜;贫铜贫锌条件下制备的薄膜中存在SnS_2二次相,贫铜富锌条件下制备的薄膜中存在少量ZnS二次相;富铜富锌条件下制备的薄膜中存在Cu-S二次相;二次相对薄膜光电响应具有重要影响,贫铜富锌的样品光电响应性能较好,无光电流衰减现象,光电流密度最大可达到0.6 mA/cm^2;最优成分下制备的CZTS太阳电池在100 mW/cm^2光照条件下获得光电转换效率为3.27%。

Cu2ZnSnS4 （CZTS） thin films for the absorber of thin film solar cells were prepared by annealling of electrodeposited copper zinc tin alloy. CZTS films were characterized by energy dispersive X-ray spectroscopy, scanning electron microscopy, X-ray diffraction, Raman scttering and photoelectrochemical measurement. The results show that with the increase of molar ratio of n（Cu）/n（Zn＋Sn）, FWHM of （112） peak increases firstly and then decreases. CZTS thin film with the molar ratios of n（Cu）/n（Zn＋Sn）=0.83 and n（Zn）/n（Sn）=1.31 has the optimal performance. The second phases exists in Cu-poor/Zn-poor, Cu-poor/Zn-rich and Cu-rich/Zn-rich CZTS thin films are SnS2, ZnS and Cu-S, respectively. The second phase has significant influence on photoelectrochemical property of CZTS thin films, Cu-poor/Zn-rich CZTS thin films have stable and superior photo-current density （the maximum is 0.6 mA/cm2）.Based on optimal composition, the solar cell fabricated with the CZTS thin film shows conversion efficiency of 3.27%.