Optimization of selenization parameters for fabrication of CZTSe thin film

For the formation of CZTSe films, selenization time and temperature play a crucial role in a material synthesis which in turn highly affects the properties of the films. In this work, Cu, Zn, Sn and Se were thermally-deposited sequentially on Mo coated soda-lime glass (SLG) substrates. For the formation of Cu2ZnSnSe4 (CZTSe) deposited films were annealed in a two-step process (first step 230 degrees C for 10 min and second step 450 degrees C for 5 min-30 min with 5 min interval) in Selenium (Se) atmosphere. The effect of selenization time on the structural, surface morphology, compositional, optical and electrical properties of the CZTSe films was studied. The formation of CZTSe phase is observed from XRD and Raman spectra. It was observed that with the increase in selenization time the CuSe binary phase present in the film suppressed gradually. The grain size, conductivity and mobility of the films increase whereas the band gap decreases with the increase in the hold time in the second step of selenization. The selenization time improves the properties of the films which can be suitable for solar cell applications. The study shows that optimum selenization time is essential to get a good quality CZTSe film. The device has been attempted for sample M6 and the best device obtained gives a conversion efficiency of 3.97%