Spectrally separated optical gain and triplet absorption: Towards continuous wave lasing in organic thin film lasers

Organic solid‐state integrated amplifiers and lasers

“…When pumped at a very low duty cycle (<0.1%) with pulses of 400 μm duration these sources generated sequences of laser pulses with repetition rates up to 5 MHz [191,192]. Triplet "scavengers", which are routinely used to address the problem of triplet absorption in liquidstate dye lasers, have been tested as a possible solution to the same problem in conjugated polymers [193]. Scavenger molecules are characterized by a large singlet-triplet splitting; as a result they possess a triplet state that is low in energy and can therefore collect triplet excitons that are produced in the host.…”

“…Scavenger molecules are characterized by a large singlet-triplet splitting; as a result they possess a triplet state that is low in energy and can therefore collect triplet excitons that are produced in the host. The use of a non-vertical triplet scavenger [cyclic nonaromatic polyene, 1,3,5,7-cyclooctatetraene (COT)] and a vertical one (anthracene) [193] led to considerable tripletexciton quenching, in films of the polyfluorene derivative poly(9,9-bis(2-ethylhexyl)fluorene-2,7-diyl) (PF2/6), however, no cw laser operation was attained in practice. Inspired by this report on scavenger molecules in the context of achieving cw laser oscillation in organic semiconductors, recent work has focused on introducing in the guest (DCM2) -host(Alq 3 ) gain medium molecules of 9,10-di(naphtha-2-yl)anthracene (ADN) to play the role of the so-called "triplet manager" [194].…”

Quasi‐Continuous‐Wave Organic Thin‐Film Distributed Feedback Laser

“…[ 10 ] Therefore, the development of organic laser dyes with less spectral overlap between the excited-state absorption and emission is crucial for the realization of cw and quasi-cw lasing with low threshold.In our group, we have continuously investigated the optical and amplifi ed spontaneous emission (ASE) characteristics of many organic materials with the aim of realizing electrically pumped organic laser diodes. [21][22][23][24][25][26][27] Among them, 4,4′-bis[( Ncarbazole)styryl]biphenyl (BSBCz) is one of the most promising candidates because a vacuum-deposited fi lm of the host material 4,4′-bis( N -carbazolyl)-1,1′-biphenyl (CBP) blended with 6 wt% BSBCz, the chemical structures of which are shown in Figure 1 a, possesses outstanding optical and ASE characteristics, such as a high photoluminescence quantum yield ( Φ PL ) of nearly 100% and short PL lifetime ( τ PL ) of about 1.0 ns, leading to a large radiative decay constant ( k r ) of about 10 9 s −1 and low ASE threshold energy of about 0.3 µJ cm −2 .…”

“…We obtained Λ = 280 ± 2 nm and a grating depth of d = 70 ± 5 nm from the SEM images, which are in perfect Since the discovery of organic solid-state lasers, [1][2][3][4][5][6] great efforts have been devoted to the development of continuous-wave (cw) lasing in organic materials, which include small molecules, oligomers, and polymers. [7][8][9][10] However, the operation of organic solid-state lasers under optical cw excitation or pulse excitation at a very high repetition rate (quasi-cw excitation) is extremely challenging. When organic fi lms are optically pumped under such conditions, accumulation of long-lived triplet excitons and charge carriers generally occurs, [11][12][13][14] resulting in an increased absorption loss by the triplet exciton formation and quenching of singlet excitons by triplet excitons (namely, singlet-triplet annihilation).…”

Itaco-perinone as a molecule with potential use in white light emitting materials. The effect of methyl- and methylene groups on the formation of perimidine and perinone structures

“…It is important to note that there is an exponential increase of the integrated luminescence as a function of laser power, which clearly demonstrates a tendency to optical gain of this material. 27 …”