Due to the PV modules are exposed to the external environment, it is necessary to clean or replace the protective glass upon contamination. In this study, we demonstrate a large-area and flexible anti reflective film with moth-eye pattern fabricated by using a highly straightforward process: nano imprint lithography. In addition, the fabricated anti-reflective film exhibits self-cleaning capability owing to the hydrophobic self-assembled-monolayer-coated surface. The fabricated anti-reflective film was attached to the surface of photovoltaic (PV) modules and placed outdoor to conduct a seven-month field test in order to observe the increase in the conversion efficiency of the PV modules as a result of the effect of the anti-reflective film. Two types of patterns, moth-eye pattern and micro-cone pattern, were used as the anti-reflective patterns: these were conveniently fabricated by the ultraviolet-nanoimprint lithography process, which does not use vacuum or high-temperature process. In the seven-month analysis, the moth-eye patterned film was observed to exhibit a transmittance that is 5.0% higher than that of the flat film, whereas the PV module with the moth-eye patterned film on its surface exhibited a conversion efficiency that is 2.85% higher than that of the PV module with the flat film. (C) 2018 Elsevier Ltd. All rights reserved.