1：Experimental Design and Method Selection:

The SnS absorber layer was grown on an ~1-μm-thick Mo/soda-lime glass (SLG/Mo) substrate using the vapor transport deposition (VTD) method. The ZnxCd1-xS buffer layers were deposited using the successive ionic layer adsorption and reaction (SILAR) method.

2：Sample Selection and Data Sources:

SnS granules (i-Tasco,

3：999%) were used as the source for SnS film deposition. The ZnxCd1-xS buffer layers were deposited on fluorine-doped tin oxide (FTO) and SLG/Mo/SnS substrates. List of Experimental Equipment and Materials:

A one-zone furnace (S&R Korea, SRDVF-LV-3B-1608) for SnS deposition, SILAR deposition unit (Opto-Mechatronic Pvt. Ltd., HOLMARC) for buffer layer deposition, and various chemicals including cadmium acetate, zinc acetate, and sodium sulfide.

4：Experimental Procedures and Operational Workflow:

Sequential steps of substrate immersion into cationic and anionic precursors were performed for the SILAR deposition. The thickness and composition of the ZnxCd1-xS films were controlled by varying the deposition cycles and the Zn-to-Cd ratio.

5：Data Analysis Methods:

UV-Vis spectrophotometry, SEM, XRF, XPS, and temperature-dependent Voc analysis were used to characterize the materials and devices.