1：Experimental Design and Method Selection:

The Gr–CdS nanocomposite was prepared by a chemical solution method. The synthesized pure CdS nanoparticles (NPs) and Gr–CdS nanocomposites were characterized by several analysis techniques including EDS, XPS, XRD, Raman spectroscopy, and TEM.

2：Sample Selection and Data Sources:

Samples included pure CdS NPs and Gr–CdS nanocomposite films prepared on bare soda-lime glass (SLG) and molybdenum sandwiched between SLG and CIGS substrates.

3：List of Experimental Equipment and Materials:

Equipment used included X-ray diffraction (XRD), transmission electron microscopy (TEM), Raman spectroscopy, energy-dispersive spectrometry (EDS), X-ray photoelectron spectroscopy (XPS), and UV–vis–NIR spectroscopy. Materials included cadmium sulfate (CdSO4), thiourea [SC(NH2)2], and graphene aqueous solution.

4：Experimental Procedures and Operational Workflow:

The CdS NPs and Gr–CdS nanocomposites were synthesized at room temperature for a reaction time of 2 h, centrifuged, rinsed, and dried. Films were prepared by spin-coating on substrates.

5：Data Analysis Methods:

The optical properties were examined by UV–vis–NIR spectroscopy, and the photovoltaic performance was evaluated by measuring the illuminated current density–voltage (J–V) characteristics under AM 1.5 one-sun conditions.