Dual-functional antireflection and down-shifting coating for Si solar cells

It is important for Si solar cells to make full use of sunlight by minimizing spectral mismatch and reducing light reflection. Herein, ZnO nanoparticles coating, which has a dual function of antireflection and down-shifting, was prepared on Si substrate by the sol-gel method. The obtained ZnO coating has a uniform structure, low roughness, and good mechanical robustness. The ZnO coating on Si substrate has a remarkable antireflection enhancement effect, with an average reflectance was 10.83% at the 400 similar to 1100 nm band, which was 19.43% lower than that of the uncoated Si substrate. Moreover, ZnO nanoparticles coatings can absorb light before 400 nm and convert it to about 527 nm, showing an apparent down-shifting effect. The photocurrent of the coated solar cells was significantly improved, with an average photocurrent increase of 21% at 300-800 nm. The coatings prepared herein with both antireflection and down-shifting luminescence properties are important for improving the photovoltaic conversion efficiency of solar cells.