1：Experimental Design and Method Selection

The study employed UV-ozone treatment at room temperature for surface passivation of CZTS films. The methodology included the use of a commercial digital UV ozone system for treatment, followed by chemical bath deposition (CBD) for CdS buffer layer deposition.

2：Sample Selection and Data Sources

CZTS films were fabricated by sulfurization of a magnetron sputtering deposited metal stacking precursor on Mo coated soda lime glass. The samples were treated with UV-ozone for different durations to study the effect on surface chemistry and solar cell performance.

3：List of Experimental Equipment and Materials

Commercial digital UV ozone system (PSD Pro Series, Novascan), magnetron sputtering system, rapid thermal process (RTP) furnace, chemical bath deposition setup, field emission scanning electron microscope (SEM, Zeiss Sigma), X-ray photoelectron spectroscopy (XPS, Kratos AXIS), ultraviolet photoelectron spectroscopy (UPS), Raman spectrometer (Renishaw), solar simulator (Newport), PicoHarp 300 time-correlated-single-photon-counting system.

4：Experimental Procedures and Operational Workflow

The CZTS films were treated with UV-ozone for varying durations after HCl etching. CdS buffer layer was deposited using CBD, followed by the deposition of ZnO and ITO window layers. The solar cells were characterized using SEM, XPS, UPS, Raman spectroscopy, J-V measurements, EQE measurements, PL, and TRPL.

5：Data Analysis Methods

Data analysis included fitting of XPS spectra, calculation of work function from UPS, extraction of solar cell parameters from J-V curves, and analysis of PL and TRPL data to understand recombination mechanisms.