Fig. 4: Applications for night vision imaging and information security.

a Photographs taken with (I) a normal smartphone under daylight, (II) a normal smartphone in the dark, (III) a smartphone equipped with the PMI-CBN/DBU/PMMA film in the dark (NIR source, 1050 nm). b Photograph of the printed words captured by the smartphone without/with PMI-CBN/DBU/PMMA film, where “F, a, n” were printed in red, green and blue inks, respectively, while the “g, Group” printed in black ink. Note: The letter “G” was covered with a NIR reflecting filter. c Reading information from a hidden QR code.