HIGH EFFICIENCY OF CZTS_E SOLAR CELLS PREPARED BY ELECTRODEPOSITED CU/SN/ZN PRECURSORS FOLLOWED BY THREE-STEP SELENIZATION AT LOW SE PRESSURE

摘要

Cu_2ZnSnSe_4 (CZTSe) thin films are prepared by the electrodeposition of stack copper/tin/zinc (Cu/Sn/Zn) precursors, followed by three-step selenization at low Se pressure. The Sn loss and the formation of molybdenum diselenide of CZTSe thin films under low Se pressure are studied. It is found that the Sn loss and the formation of molybdenum diselenide in CZTSe thin films can be neglected by using three-step selenization at low Se pressure. The 1st selenization leads to fine grain microstructure. The 2nd anneal step produces significant grain growth. The 3rd selenization step adjusts the composition of thin films. After properly controlling the selenization parameters, the efficiency of as high as 8.2% in CZTSe solar cells can be obtained by this low-cost preparation method.