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A dye-sensitized solar cell (DSSC) device using Mg-doped Zn thin films as photoanode and fruit extract of rose myrtle (Rhodomyrtus tomentosa) as the natural dye was investigated. The effect of annealing temperature (400-550°C) on the films of photoanode was systematically studied using an X-ray diffractometer (XRD), UV-Visible Near Infrared (UV-Vis NIR) Spectrophotometer, scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). XRD confirm that all sample has the wurtzite hexagonal with crystallite size of 25 nm. The SEM images reveal particles on the surface of the Mg-doped ZnO thin film of irregular shapes. Increasing the annealing temperature leads to a larger particle size and slightly increases bandgap energy. The dye sensitizer of extracted rose myrtle (Rhodomyrtus tomentosa) has a strong absorption at the visible light region. The maximum efficiency of the DSSC device is 3.53% with Mg-ZnO photoanode annealed at 500°C.

This study aims to determine the effect of the TGT (Teams Games Tournaments) cooperative learning model on students’ conceptual knowledge on momentum and impulse material in grade X 7th state Senior High School (SMA) in Medan City. The research type is a quasi-experiment with a two-group pretest-posttest design. The instrument used in this study was a test of students’ conceptual knowledge in the form of multiple choices and an assessment sheet to measure student skills and student activities. After the learning was given, the two classes carried out a post-test. The experimental class obtained an average value of 83.19 and for the control class, an average value of 64.58 was obtained. And student learning activities in the cooperative learning process type TGT (Teams Games Tournaments) in three meetings experienced an increase with an average value of 72.4 (active) meeting I, 77.22 (active) meeting II, 82, 4 (active). Based on the test results, it was found that the cooperative learning model type teams games tournament had a significant effect on students’ conceptual knowledge on momentum and impulse material in grade X 7th state SMA in Medan City.

Fluoro-borophosphate glass containing Natrium Fluoride (NaF) doped with Samarium ion 1 mol% concentration. The glass compositions based on 49P2O5-5B2O3-15ZnO-15Li2O-15NaF-1Sm2O3 are prepared by melting and quenched technique. The optical and photoluminescence were obtained from the UV-Vis-NIR spectrophotometer and spectrofluorophotometer. The ground state 6H5/2 as the start transition in the absorption spectrum and the Judd-Ofelt intensity parameters (2, 4, and 6) were determined. The emission spectra of borophosphate glass with NaF were recorded at an excitation of 401 nm which gave four peaks namely 6H5/2, 6H7/2, 6H9/2, and 6H11/2..

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.