The Effect of Spin Coating Speed on Structural and Optical Properties of ZnO and ZnO/Dye Thin Films Synthesized by Sol-Gel Spin Coating Method

The ZnO thin films were successfully synthesized using sol-gel spin coating method. The surface other ZnO thin film then were coated with natural dye. Materials used were zinc acetate dehydrate, isopropanol, Diethanolamine and purple heart flower consecutively as based materials, solution, stabilizer, and dye. The ZnO thin films were grown glass by dropping Sol-gel on a surface of FTO glass with spin coating speed variation of 2000, 3000, 4000, and 6000 rpm. The ZnO thin films then successively pre-heated and pot-heated at 250°C and 550°C for 5 hours and holding time of 30 minutes. The source of the dye is boat lily flower was cut into small pieces and put into beaker glass. The sample then crushed with mortar and then milling until it becomes soft. Further, the extract was obtained by immersing it in aquadest, acetate acid, and ethanol with maceration technique. The ZnO thin films then immersed in an extract of dye solution for 24 hours to obtain ZnO/dye thin film. The XRD analysis shows that ZnO thin film size of within 26.5 – 36.9 nm. The optical properties of the ZnO and ZnO/Dye thin films were characterized using UV-Vis spectrometer. The UV-Vis spectrometer results show that there are variations of the ZnO thin film transmission as a result of spin coating speed of the Sol-gel spin coating method. The transmission of ZnO/dye thin films is higher than ZnO thin film and the absorbance of ZnO is higher than ZnO/dye thin films. The band gaps of the ZnO and ZnO/dye thin film were consecutively ranged 3.27 – 3.34 eV and 3.02 – 3.21 eV. (paper)