Synthesis and Characterization of NaOH-Doped ZnO Metal Oxide Thin Films for Electron Transport Layer in Dye-Sensitized Solar Cells (DSSCs) W. S. Arsyad, H. A. Hangkea, I. Saleh, I. N. Sudiana, L. Agusu, I. Usman International Journal of Acta Material Vol. 2 No. 2 2026 DOI 10.62749/ijactmat.v2i2.30