(a) Normalized absorption
(blue) and photoluminescence (PL) (orange)
spectra of the MEH-PPV in chlorobenzene solution; (b) ASE spectra
of the reference MEH-PPV solution without nanostars, excited by single
pulses at different excitation fluences. The intensity of the PL spectra
of MEH-PPV at a pumping fluence of 0.12 mJ cm–2 (dashed
orange curve) was magnified 45 times for comparison. (c–h)
Spectral overlap of the MEH-PPV absorption and emission spectra (dotted
curves) with the extinction spectra of respective silica-coated nanoparticles
in chlorobenzene (solid lines) and the emission (ASE or random lasing)
spectra at different excitations fluences for nanoparticles/MEH-PPV
mixtures: (c,d) AuNPs@SiO2, (e,f) AuNSts@SiO2, (g,h) AuAgNSts@SiO2, respectively. The inset in (d)
shows the TEM image of a representative AuNP@SiO2 nanoparticle.
The scale bar is 100 nm.