Optimized dual-band amplified spontaneous emission properties of PFO and BUBD-1 blend films based on AgNPs doped buffer layers

Dual-band amplified spontaneous emission (ASE) can be used as a spectral analysis technique to detect specific chemical or biological molecules. In this paper, the dual-band ASE properties of blend films containing a small organic molecule N,N’-(4,4′-(1E,1′E)-2, 2′-(1,4-phenylene) bis(ethene-2,1-diyl)) −bis(4,1-phenylene))-bis(2-ethyl-6-methyl-phenylaniline) (BUBD-1) and a conductive polymer Poly(9,9-dioctylfluorenyl-2,7-diyl) (PFO) were investigated and optimized. As the doping concentration of BUBD-1 in the PFO was increased from PFO: 1 wt% BUBD-1 to PFO: 5 wt% BUBD-1, the ASE emission wavelength shifted from single- to dual-band and then back. The dual-band ASE performance of the blend film was also improved by introducing a Poly(methyl methacrylate) (PMMA) buffer layer containing silver nanoparticles (AgNPs), which resulted in a significant decrease in the excitation energy threshold of both ASE peaks and a significant increase in the net gain. Due to the LSPR effect of AgNPs, the ASE thresholds for peaks at 460 nm (PFO) and 490 nm (BUBD-1) in the blend film decreased from 12.24 ± 0.49 μJ/pulse to 6.99 ± 0.28 μJ/pulse and from 12.75 ± 0.51 μJ/pulse to 7.03 ± 0.28 μJ/pulse, respectively. The experimental and theoretical simulation demonstrated that the incomplete energy transfer between PFO and BUBD-1 led to a dual-band ASE effect. In addition, the enhanced light absorption, emission, and scattering caused by LSPR in the AgNPs improved the threshold and gain for dual-band ASE. This provides a possibility of realizing dual-band organic semiconductor lasers.