1：Experimental Design and Method Selection:

The study employed electrochemical deposition to prepare Cu2O thin films on fluorine doped tin oxide (FTO) substrates at various bath temperatures (40, 55, and 70 °C). The structural, morphological, vibrational, optical, and electrical properties were analyzed using XRD, SEM, Micro Raman spectroscopy, PL spectroscopy, UV–visible spectroscopy, LCR measurement, and Keithley 4200 semiconductor characterization system.

2：Sample Selection and Data Sources:

FTO glass substrates were used as the working electrode, with platinum and Ag/AgCl serving as counter and reference electrodes, respectively. The deposition solution contained 0.15 M CuSO4·5H2O and 1 M Lactic acid in 30 ml of deionized water, with pH adjusted to around 11 using NaOH.

3：15 M CuSO4·5H2O and 1 M Lactic acid in 30 ml of deionized water, with pH adjusted to around 11 using NaOH. List of Experimental Equipment and Materials:

3. List of Experimental Equipment and Materials: X-ray diffraction meter system (X’PERTPRO PAN analytical), scanning electron microscopy (ZEISS), Micro Raman Spectroscopy, Photoluminescence spectroscopy (RF-6000, SHIMADZU), UV–Vis-NIR spectroscopy (UV-1800, SHIMADZU), stylus profilometer, LCR spectroscopy, Keithley semiconductor characterization system

4：Experimental Procedures and Operational Workflow:

42 The Cu2O films were deposited at a constant potential of ?0.4 V for 30 min. The influence of bath temperatures on the properties of Cu2O thin films was studied by varying the temperature from 40 to 70 °C.

5：4 V for 30 min. The influence of bath temperatures on the properties of Cu2O thin films was studied by varying the temperature from 40 to 70 °C. Data Analysis Methods:

5. Data Analysis Methods: The crystallite size was calculated using Debye–Scherrer’s equation, dislocation density and micro strain were estimated using specific equations, and the optical band gap was determined using Tauc’s plots.