1：Experimental Design and Method Selection:

The study involved depositing phosphonic acid diarylethene (PA-DAE) SAMs on ITO electrodes to modify their electronic properties. Methods included surface characterization techniques such as scanning force microscopy (SFM), water contact angle measurements, X-ray photoemission spectroscopy (XPS), X-ray absorption spectroscopy (XAS), ultraviolet photoemission spectroscopy (UPS), and Kelvin probe force microscopy (KPFM), combined with density functional theory (DFT) calculations to understand the binding mechanisms and electronic changes.

2：Sample Selection and Data Sources:

ITO-coated glasses with a sheet resistance of 20 Ω/□ were used as substrates. PA-DAE molecules were synthesized as reported in Ref 18. Samples were prepared by immersing ITO in a 1 mM PA-DAE solution in anhydrous THF, followed by annealing and sonication to achieve high-density SAM coverage.

3：Samples were prepared by immersing ITO in a 1 mM PA-DAE solution in anhydrous THF, followed by annealing and sonication to achieve high-density SAM coverage. List of Experimental Equipment and Materials:

3. List of Experimental Equipment and Materials: Equipment included a Theta Lite setup for contact angle measurements, a Jandel four-point probe with RM3000 source measure unit for sheet resistance, a PerkinElmer Lambda 950 spectrometer for UV-vis absorption, a SurICat end station at beamline PM4 at BESSY II for PES and XAS, a custom-made system for UPS and XPS with He I and Al Kα sources, a Bruker Dimension FastScan SFM system, and high-power LEDs from Thorlabs for illumination. Materials included ITO substrates, PA-DAE molecules, and solvents like acetone, isopropanol, and THF.

4：Experimental Procedures and Operational Workflow:

ITO substrates were cleaned by sonication in acetone and isopropanol. SAM deposition involved immersion in PA-DAE solution, annealing at 90°C, and sonication in THF to remove physisorbed molecules, repeated three times. Characterization steps included SFM imaging, contact angle measurements, XPS and UPS measurements with synchrotron radiation, XAS for molecular orientation, and KPFM for surface potential changes. Illumination with UV (365 nm) and green (565 nm) light was performed in situ to switch PA-DAE between open and closed forms.

5：Data Analysis Methods:

Data were analyzed using fitting procedures for spectra (e.g., Voigt and Doniach-Sunjic profiles), DFT calculations with PBE functional in VASP code for electronic structure and binding energy shifts, and statistical analysis for parameters like packing density and tilt angle.