钾掺杂对柔性CZTSSe薄膜及其太阳电池性能的影响

Effect of K-Doping on Properties of Flexible CZTSSe thin films and Performance of Solar Cells

本文采用磁控溅射加后续硒化的方法制备柔性CZTSSe薄膜,通过向硒化气氛中引入钾元素实现了钾的有效掺杂。研究了钾掺杂量对柔性CZTSSe薄膜和电池性能的影响。X射线衍射和Raman结果表明适量掺入钾元素可以显著提高CZTSSe薄膜的(112)择优取向,增大晶粒尺寸,但钾元素掺杂量过高时又会使晶粒尺寸变小降低薄膜结晶性。另外钾元素的掺入也会改变CZTSSe/Cd S间能带匹配情况,少量的钾元素掺杂对CZTSSe/Cd S间导带失调值(CBO)影响不大,过量掺入钾元素则会明显增大CZTSSe/Cd S间的CBO绝对值,进而降低柔性CZTSSe太阳电池转换效率。发现钾元素掺杂量为1. 0μmol时,所制备的柔性CZTSSe薄膜平均晶粒尺寸超过1μm,且具有很强的(112)择优取向;制作的CZTSSe/Cd S具有最佳的CBO数值,相应柔性太阳电池的最高值转换效率为3. 06%。

Flexible K-doped CZTSSe thin films were synthesized by selenizing the magnetron co-sputtered precursors. The influence of the K-content on the microstructures,energy band structures of the thin film and performance of the solar-cells was investigated with X-ray diffraction,X-ray photoelectron spectroscopy,scanning electron microscopy and Raman spectroscopy. The preliminary results show that the K-content had a major impact. For example,as the K-content increased,< 112 > preferentially-oriented growth became increasingly obvious,the grain-size changed in an increase-decrease mode;the over amount K-induced conduction band offset( CBO) increased and the CBO absolute-value at CZTSSe/CdS interface increased because K-doping induced band structure re-alignment,resulting in efficiency deterioration of solar-cell. With K-content of 1. 0 μmol,the < 112 > preferentially grown CZTSSe thin film had average grain-size of 1 μm and optimal CBO at CZTSSe/CdS interface. Moreover,the highest efficiency of the K-doped flexible solar-cell reached 3. 06%.