NOVELTY - An anti-reflective coating film (50) formed from a coating solution composition comprises a silane-based precursor, where the coating solution composition exhibits a peak intensity IB of 930-960 cm-1; a peak intensity IA of 1110-1130 cm-1; and a peak intensity IC of 1020-1050 cm-1 measured via Fourier Transform Infrared (FT-IR) Spectroscopy using a wavelength of 1064 nm, where a peak intensity ratio IB/IA and a peak intensity ratio IC/IA are each greater than or equal to 0.47.    USE - As an anti-reflective coating film formed from a coating solution composition; for solar cell such as thin film solar cell; and for predicting strength of an anti-reflective coating film for a solar cell (claimed).    ADVANTAGE - The anti-reflective coating film have low refractivity and a certain level of strength to maintain the performance of the solar cell module at a level of plus minus 5% for a period of 5-20 years to minimize (or reduce) loss in the anti-reflective coating film due to external conditions. Thus, the open voltage (VOC) of a solar cell can be increased to improve the efficiency of the solar cell.    DETAILED DESCRIPTION - An anti-reflective coating film (50) formed from a coating solution composition comprises a silane-based precursor, where the coating solution composition exhibits a peak intensity IB representing a Si-OH bond of 930-960 cm-1; a peak intensity IA representing a Si-O-Si bond of 1110-1130 cm-1; and a peak intensity IC representing a Si-O-R (where R is 1-5C alkyl) of 1020-1050 cm-1 measured via Fourier Transform Infrared (FT-IR) Spectroscopy using a wavelength of 1064 nm, where a peak intensity ratio IB/IA and a peak intensity ratio IC/IA are each greater than or equal to 0.47. INDEPENDENT CLAIMS are included for the following:    (1) solar cell comprising a substrate, a photoelectric conversion layer comprising an optical absorber layer on the substrate, a cover glass on the photoelectric conversion layer, and the anti-reflective coating film on the cover glass;    (2) predicting a strength of an anti-reflective coating film for a solar cell involving measuring a coating solution composition comprising a silane-based precursor via FT-IR Spectroscopy using a wavelength of 1064 nm, for a peak intensity ratio IB/IA and a peak intensity ratio IC/IA respectively, where the peak intensity IB represents a Si-OH bond of 930-960 cm-1, the peak intensity IA represents a Si-O-Si bond of 1110-1130 cm-1, and the peak intensity IC represents a Si-O-R of 1020-1050 cm-1, respectively, and predicting whether the anti-reflective coating film has a strength equal to or greater than a pencil hardness 4H based on the peak intensity ratio IB/IA and the peak intensity ratio IC/IA.    DESCRIPTION OF DRAWING(S) - The figure shows a view of a thin film solar cell.    Substrate (10)    Photoelectric conversion layer (20)    Encapsulant layer (30)    Cover glass (40)    Anti-reflective coating film (50)    Thin film solar cell (60)