Fig. 1

Chemical structures of nanographenes and their optical properties dispersed in polystyrene films. a Chemical structures of nanographenes FZ1, FZ2, and FZ3, respectively. b Optical properties at room temperature of PS films doped with 1 wt% of FZ1, FZ2, and FZ3, from top to down. Absorption coefficient, α (solid line, left axis), photoluminescence intensity (dashed line, right axis), and amplified spontaneous emission, ASE, intensity (filled area, right axis), versus wavelength, λ. c Low temperature (80 K) PL spectra of the three nanographenes in methyl tetrahydrofurane (methyl THF) solution. The wavelengths of each peak, and the spacing (in red, in cm⁻¹) for each vibrational progression are indicated. d Net gain coefficients, g_net, obtained from plots such as those of Supplementary Fig. 3, versus the pump energy density, E_pump, for a 1 wt% FZ2-doped PS film. The full line is a guide to the eye and its intersection with the y-axis corresponds to the loss coefficient (k = 9 ± 1 cm⁻¹). Errors in g_net were estimated statistically as the standard deviation from measurements on several nominally identical samples. Source data are provided as a Source Data file in the Institutional Repository of the University of Alicante [http://hdl.handle.net/10045/92007]