University of California, Santa Barbara
Faculty Sponsor's Department(s):
Electrical and Computer Engineering
Investigation on the Effects of Spin Speed on the Properties of Spin-Coated Cu2ZnSnS4 Thin Film
Semiconductor, Cu2ZnSnS4 (CZTS), is one of the most promising absorber layer materials for low cost thin-film solar cells due to its large absorption coefficient of over 104cm-1 and its optical band gap of ~1.5eV. In addition, CZTS is only made of abundant and non-toxic elements. Current commercialized semiconducting materials for thin-film solar cells have high conversion efficiency. However, the elements that are used in these systems are scarce in the earth’s crust and have toxic properties. In this work, the effects of spin speed on the properties of CZTS thin films were investigated. Six thin film samples were fabricated by spin coating at respective spin speeds of 2000, 4000, 6000, 8000, 10000 and 12000 revolution per minute (rpm). After spin coating, each sample was solvent-dried and then annealed. After the fabrication process, the samples were characterized to identify their respective properties. UV Vis NIR Spectroscopy was used to measure and calculate the absorbance rates and band gaps. X-Ray Diffraction (XRD) was used to measure their respective Full Width at Half Maximum (FWHM) and crystallite size. Scanning Electron Microscope (SEM) was used to identify the morphology (size, dense packing, and uniformity of grains). Lastly, Raman spectroscopy was used to determine the formation of single-phase kesterite CZTS due to the overlapping peaks of the CZTS and other phases. CZTS has already shown promising results with solar cells efficiency of 12.6%. However, further improvement is required for it to be commercialized.