Antireflective coating using a WO3–TiO2 nanoparticle photocatalytic composition for high efficiency thin-film Si photovoltaic modules

•ARC using the WO3–TiO2 nanoparticle photocatalyst is applied to thin-film Si PV modules.•The coated nanoporous films provide the broadband antireflective effect.•The self-cleaning effect due to the photo-induced superhydrophilicity plays an important role.•The energy output gain of 3.6% is obtained for the a-Si:H single-junction PV module via ARC.•The energy output gain of 4.3% is achieved for the a-Si:H/µc-Si:H tandem PV module due to ARC.

We propose a cost-effective, low-temperature antireflective coating for the outer glass substrates of 1.43 m2 thin-film Si photovoltaic modules using a WO3–TiO2 nanoparticle photocatalyst. The coated nanoporous films provide the broadband antireflective effect, which results in the increased initial performances. Notably, the self-cleaning effect due to the photo-induced superhydrophilicity leads to a significantly reduced outdoor-exposed degradation. Therefore, the drastic energy output gain of 4.3% is achieved for a tandem photovoltaic module via a long-term outdoor field test.