| 초록 |
Recently, kesterite based thin film solar cells (TFSCs) are greatly acknowledged in the photovoltaic industry for their elemental earth abundance and less toxic approach. Herein we employ co-sputter and stack method to deposit Cu, Zn and Sn precursors and study the alloying behavior with respect to temperature. The chemical, structural, and morphological properties of annealed precursors are analyzed through X-ray diffraction (XRD), X-ray fluorescence (XRF), Raman scattering spectroscopy and scanning electron microscopy (SEM). The XRD study reveals, both precursors start to alloy above 400 ℃ and forms pure CZTSSe phase above 500 ℃. The morphological study shows the co-sputtered precursor exhibits homogenous distribution of metallic grains with compact morphology and negligible voids compared to stack. These homogenous and smaller metallic grains start to alloy at 500 ℃ much faster as compared to stack, which pointedly assists the formation of larger absorber grains. The XRF measurements showed the precursor chemical composition changes with change in annealing temperature. Besides, it also shows increasing Sn loss and high Cu/(Zn+Sn) ratio with increasing temperature in all sulfo-selenized thin films. The improved morphology of co-sputtered precursor showed over 10 % device efficiency as that of the stack, proving this method can be used to achieve the high efficiency in TFSCs with reduced process time |
