Fig. 2

SEM images of PS NSs with diameter of 100, 200, and 500 nm at the average dip-drop speed of a, d, g 0.05 mL/s; b, e, h 0.01 mL/s; and c, f, i 0.005 mL/s, and the SEM images of PS NSs with 200 nm and average dip-drop speeds of 0.005 mL/s at the regions of j upper-right, k upper-left, l lower-right, and m lower-left of 0.5 × 0.5 mm2 ITO-coated glass substrate . The concentrations of DI water-diluted PS NS suspension were 4.1 × 1011 spheres/cm−3 for the 100-nm PS NSs, 5.1 × 1010 spheres/cm−3 for the 200-nm PS NSs, and 3.2 × 109 spheres/cm−3 for the 500-nm PS NSs