%0 Journal Article
%T Interfacial Properties of CZTS Thin Film Solar Cell
%A N. Muhunthan
%A Om Pal Singh
%A M. K. Thakur
%A P. Karthikeyan
%A Dinesh Singh
%A M. Saravanan
%A V. N. Singh
%J Journal of Solar Energy
%D 2014
%I 
%R 10.1155/2014/476123
%X Cu-deficient CZTS (copper zinc tin sulfide) thin films were grown on soda lime as well as molybdenum coated soda lime glass by reactive cosputtering. Polycrystalline CZTS film with kesterite structure was produced by annealing it at 500¡ãC in Ar atmosphere. These films were characterized for compositional, structural, surface morphological, optical, and transport properties using energy dispersive X-ray analysis, glancing incidence X-ray diffraction, Raman spectroscopy, scanning electron microscopy, atomic force microscopy, UV-Vis spectroscopy, and Hall effect measurement. A CZTS solar cell device having conversion efficiency of ~0.11% has been made by depositing CdS, ZnO, ITO, and Al layers over the CZTS thin film deposited on Mo coated soda lime glass. The series resistance of the device was very high. The interfacial properties of device were characterized by cross-sectional SEM and cross-sectional HRTEM. 1. Introduction The optical and electronic properties of CZTS make it a suitable absorber layer for thin film photovoltaic. CZTS made from earth abundant and nontoxic elements is an ideal candidate to replace Cu(In,Ga)Se2 (CIGS) and CdTe which face material scarcity and toxicity issues for large scale production of solar cells. Therefore, thin film CZTS solar cell has received great attention in recent years [1¨C5]. CZTS is reported to have a band gap between 1.40 to 1.50£¿eV [1¨C5] and a band edge absorption coefficient above 104£¿cm£¿1 which makes it highly attractive as a single junction solar cell material. Efficiency up to 8.4% and 12.6% have been achieved for CZTS [6] and Cu2ZnSn(S,Se)4 (CZTS,Se) [7] solar cells, respectively. Efficiency of nearly 6.2% has been achieved using cosputtering of Cu, ZnS, and SnS target in Ar atmosphere [8]. In the case of CIGS and CdTe thin film solar cells, the best efficiency reported is ~21.7% [9] and 20.4% [10], respectively. The CZTS thin film solar cell device property is affected by the presence of phase impurities like Cu2S, Cu2SnS3, ZnS, SnS, and so on and poor quality of interfaces [11¨C14]. The open circuit voltage of the device which depends on the career generation and recombination process is controlled by the presence of defects [15¨C18]. The poor interfacial properties also affect the performance of the device [19, 20]. Generally, two-step process is used for the deposition of CZTS thin film (metallic film deposition and then sulfurization). In the two-step process, during sulfurization, the film surface becomes rough which may hinder the formation of proper junction when n-type CdS is coated over it and
%U http://www.hindawi.com/journals/jse/2014/476123/