ZnS溅射功率对Cu2ZnSnS4薄膜附着性及太阳电池性能的影响

Influence of ZnS Sputtering Power on Cu2ZnSnS4 Thin Film Adhesion and Performance of Solar Cells

采用不同ZnS溅射功率,在钠钙玻璃(SLG)衬底上依次溅射Mo、ZnS、SnS及Cu,退火后制备出Cu2ZnSnS4(CZTS)薄膜。研究了溅射功率(50~140W)对ZnS薄膜和CZTS薄膜的微观形貌、微结构以及附着性的影响。结果表明,不同功率溅射的ZnS薄膜为(008)择优取向的纤锌矿六方晶系结构;功率较低时,ZnS薄膜结晶质量较差;随着功率从50 W增加到140 W,ZnS薄膜内的压应力增加了一个数量级;ZnS溅射功率低于80 W或高于110 W时,退火后的CZTS薄膜发生龟裂甚至脱落;ZnS溅射功率在80~110 W时,退火后CZTS薄膜表面均匀平整;110 W溅射后的CZTS薄膜出现较多的孔洞和二次相。采用80 W功率溅射ZnS薄膜制备的CZTS/CdS太阳电池,开路电压达到572 mV,短路电流密度为14.23 mA/cm^2,光电转换效率为3.34%。

The stacking precursors SLG/Mo/ZnS/SnS/Cu were sputtered ZnS,SnS and Cu target in sequence on soda-lime glass(SLG)substrates in which the sputtering power of ZnS changed from 50 W to 140 W.Then Cu2ZnSnS4(CZTS)thin films were obtained by annealing.The effects of ZnS sputtering powers on the morphology,microstructure and adhesion in ZnS thin films and followed CZTS thin films were investigated.The results showed that the ZnS thin films with different power sputtering were hexagonal wurtzite with(008)preferred orientation.The poor crystallization in ZnS thin film was found at low sputtering power.The compressive stress in ZnS thin film increased by an order of magnitude with sputtering power from 50 W to 140 W.When sputtering power of ZnS was lower than 80 W or higher than 110 W,the crack and even falling off phenomenon were observed in the annealed CZTS thin films.From 80 W to 110 W,the surface of CZTS thin film was even but more holes and se-condary phases appeared at higher power of 110 W.The CZTS solar cell was prepared with ZnS thin films sputtered at 80 W,which showed open circuit voltage of 572 mV,short circuit current density of 14.23 mA/cm^2 and photoelectric conversion efficiency of 3.34%.