IMPACT OF PRECURSOR SEQUENCING ON THE STOICHIOMETRY OF CZTS THIN FILMS FOR PHOTOVOLTAIC APPLICATIONS

Abstract
Technological advancements have led to proportionate increase in the energy demand which has necessitated development of technologies to enable better utilization of the renewable energy sources. Among the photovoltaics, second generation solar cell materials are inexpensive and earth abundant compared to first and third generation categories. The promising candidate for the second-generation thin film solar cells are kesterite materials primarily Cu2ZnSnS4 popularly termed as CZTS. Their tuneable optical bandgap with high conductivity, p type characteristics, non-toxic characteristics, high absorption coefficient of 104 cm-1 make them preferred materials. Apart from solar cell applications, CZTS have also gained attraction in the energy storage devices, and photocatalytic applications. Integrated devices which combine solar cell and energy storage units developed on flexible substrates require materials with promising absorption and band gap characteristics along with good electrical properties. The heterojunction in multicomponent CZTS have been found to offer ideal characteristics for all three applications. The stoichiometry of CZTS is an important criterion which decides its suitability for multiple applications. Electrodeposition in single step is quite advantageous route to develop CZTS layer on desirable substrates. However, the sequence of the addition of the precursors influence the complex formation kinetics and lead to varying stoichiometries of CZTS films with different properties. This study involves studying the sequence of precursor addition and its influences in development of CZTS films. The morphology of the films thus formed were investigated using scanning electron microscopy (SEM) and the composition and crystallinity were analysed suing EDAX and XRD. The optical and the electrical properties have also been studied. Keywords - Kesterite, Electro Deposition, Precursors, Sequencing.