Fig. 2

Optical properties of 2D OIHP films: a UV–Vis absorption; b normalized photoluminescence from back (glass) side, and c from front (air) side. Transient absorption spectrum excited from back (glass) side of 2D OIHP films based on PEA (d), oF1PEA (e), mF1PEA (f), and pF1PEA (g). The excitation wavelength was chosen at the absorption peak of the particular n = 1 phase for each 2D OIHP film, i.e., 517, 506, 510, and 518 nm, respectively. Numbers and arrows indicate signals from different phases