Dual band amplified spontaneous emission in the blue in Poly(9,9-dioctylfluorene) thin films with phase separated glassy and β-phases

Determination of the Best Empiric Method to Quantify the Amplified Spontaneous Emission Threshold in Polymeric Active Waveguides

“…The PL spectra of the PFO sample show (see Figure 2 a), at low excitation density, the typical spontaneous emission spectrum of the PFO glassy phase with the 0–0 transition peak at about 425 nm, followed by 0–1 and 0–2 vibronic replicas at about 443 and 480 nm [ 55 ]. As the excitation density increases the lineshape is unchanged, up to an excitation density value of 21 at which the spectrum shows a shoulder at about 450 nm (visual threshold).…”

“…To date, optical gain and optically pumped lasing have been demonstrated in many families of conjugated molecules and with a wide range on different resonators [ 20 , 21 ] and a first indication of lasing effect under electrical pumping has been recently reported [ 22 ]. In particular the organic systems showing optical gain can be divided in the two big families of neat films or blends of active molecules [ 2 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 ,…”

“…A different approach exploits the lineshape variation due to the appearance of the ASE band, identifying the ASE threshold as the minimum excitation density at which the ASE band becomes visible [ 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 ] (Visual, 4.7%).…”

“…Our analysis is performed on thin films of three different conjugated polymers whose emission covers the entire visible range, namely poly(9,9-dioctylfluorene) (PFO), poly(9,9-dioctylfluorene-cobenzothiadiazole) (F8BT) and a blend of F8BT and regio regular Poly(3-hexylthiophene) (rrP3HT) (F8BT:rrP3HT). These polymers show good solubility in standard organic solvent, good film forming properties and efficient ASE [ 12 , 36 , 38 , 41 , 45 , 55 ], and can be thus considered good prototype materials for homopolymers (PFO), copolymers (F8BT) and host guest blends (F8BT:rrP3HT).…”

Dual Amplified Spontaneous Emission and Lasing from Nanographene Films

“…Further, fewer cases of dual ASE have been reported to occur in solid films, and most of them correspond to PFO derivatives. In them, the dual ASE is attributed to the coexistence of two phases of the polymer, which can emit simultaneously [33,34], and/or to the coexistence of a monomer and excimer [35]. Aside from these, dual ASE was found in a bifluorene derivative single crystal, which was related to the emission from two different vibronic replicas [36].…”