Temporal response of optically pumped organic semiconductor lasers and its implication for reaching threshold under electrical excitation

Giebink, Noel C.; Forrest, Stephen R.

doi:10.1103/physrevb.79.073302

Cited by 105 publications

(95 citation statements)

References 21 publications

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“…26,28,[54][55][56] In contrast, the assumption of a fixed k ISC would lead to a nearly complete depletion of the triplet state under stimulated emission.…”

Section: Organic Semiconductor Laser Modelmentioning

confidence: 99%

“…We consider both the case where stimulated emission is absent, mimicking the conditions observed in confocal scanning microscopy, 12 fluorescence lifetime imaging and organic light-emitting diodes (OLEDs), 13,22 as well as the case where it is present such as in dye lasers 23 or optically pumped organic semiconductor lasers (OSL). [24][25][26][27][28][29] In the latter, we find that although the short-time dynamics are left mostly unaffected, the achievable OSL repetition rate is increased by a factor Γ T . …”

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confidence: 99%

“…In the lowest order approximation, radiative transitions from the triplet-state (total spin S = 1) to the singlet (S = 0) ground state are forbidden. [36][37] As a result, the "dark" triplet state is the source of blinking in singlemolecule fluorescence, 38 annihilation mechanisms in lasers [23][24][25][26] and a significant source of photobleaching. 12, 14-15 Spin-orbit coupling, however, mixes the singlet and triplet states imparting the transition with a finite transition dipole moment.…”

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confidence: 99%

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Plasmonic Sinks for the Selective Removal of Long-Lived States

et al. 2011

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The use of plasmonic nanostructures for the removal of unwanted long-lived states is investigated. We show that the total decay rate of such a state can be increased by up to four orders of magnitude, as compared to its intrinsic radiative decay rate, while leaving other neighboring optical transitions unaffected. For the specific case of molecular triplet excited states, we show that the use of a "plasmonic sink" has the potential to reduce photobleaching and ground state depletion by at least two orders of magnitude. We consider, in addition, the impact of such structures on the performance of organic semiconductor lasers and show that, under realistic device conditions, plasmonic sinks have the capacity to increase the achievable laser repetition rate by a factor equal to the triplet decay rate enhancement. We conclude by studying the effect of exciton diffusion on the triplet density in the presence of metallic nanoparticles. KeywordsPlasmons, Sinks, Nanoshells, Purcell Effect, Quenching, Triplets, Organic Lasers, Photobleaching, Non-radiative decay Plasmonic nanoparticles and antennas have demonstrated significant potential for enhancing the luminescence of adjacent emitters. [1][2][3][4][5][6] The mechanisms for enhancement, however, can be varied and the origin of the increased brightness difficult to unravel. For example, the nanostructure can serve to increase the local electric field at the excitation wavelength resulting in an increased excitation rate, 7-9 or equivalently, absorption efficiency of the emitter. In addition, the scattering cross-section of the particle or radiation pattern of the antenna can lead to a higher collection or out-coupling efficiency for the emitted light. 2, 10 Finally, and most importantly for this work, the increased photonic density of states at the emission wavelength can result, via the Purcell effect, in an increased radiative decay rate, Γ R , for the emitter. [1][2][8][9][10] This effect, however, is typically concomitant with an unwanted and stronger increase in the non-radiative decay rate, Γ NR , due to Joule heating of the metal. [9][10] In the usual case where Γ NR >> Γ R , increases in quantum yield, φ F , are only possible for emitters with very low intrinsic yields 0 R NR φ < Γ Γ . 11 In this work, we show that instead of being detrimental, the high non-radiative decay rate typical of emitters in close proximity to plasmonic structures can be exploited to selectively remove unwanted excited states in a number of physical systems.In molecular systems, for example, the build-up of large triplet state populations prevents the efficient excitation of organic molecules with high repetition rates or continuous sources, 12-13 and can be a significant source of photobleaching. 14-17 Indeed,Hale et al. first proposed and demonstrated the possibility of using plasmonic nanoparticles to increase the photostability of organic thin films. 18 In a later section weshow that in that case, the effect fits into the "diffusive regime", which has several advantages, bu...

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“…26,28,[54][55][56] In contrast, the assumption of a fixed k ISC would lead to a nearly complete depletion of the triplet state under stimulated emission.…”

Section: Organic Semiconductor Laser Modelmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Plasmonic Sinks for the Selective Removal of Long-Lived States

et al. 2011

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“…However, for more than twenty years, the direct electrical excitation of stimulated emission in organic semiconductors remains a major challenge [8,9], although solid-state organic lasers demonstrated their high potential under optical pumping [10,11]. In fact, electrically-pumped organic materials exhibit several extra losses mechanisms (triplet-induced problems [12,13], charge-induced absorption [14,15] and absorption at metal contacts), which grow rapidly with the current [8], creating a negative feedback loop [10,16].…”

Section: Introductionmentioning

confidence: 99%

Gain properties of dye-doped polymer thin films

et al. 2015

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Hybrid pumping appears as a promising compromise in order to reach the much coveted goal of an electrically pumped organic laser. In such configuration the organic material is optically pumped by an electrically pumped inorganic device on chip. This engineering solution requires therefore an optimization of the organic gain medium under optical pumping. Here, we report a detailed study of the gain features of dye-doped polymer thin films. In particular we introduce the gain efficiency K, in order to facilitate comparison between different materials and experimental conditions. The gain efficiency was measured with various setups (pump-probe amplification, variable stripe length method, laser thresholds) in order to study several factors which modify the actual gain of a layer, namely the confinement factor, the pump polarization, the molecular anisotropy, and the re-absorption. For instance, for a 600 nm thick 5 wt% DCM doped PMMA layer, the different experimental approaches give a consistent value K ≃ 80 cm.MW −1 . On the contrary, the usual model predicting the gain from the characteristics of the material leads to an overestimation by two orders of magnitude, which raises a serious problem in the design of actual devices. In this context, we demonstrate the feasibility to infer the gain efficiency from the laser threshold of well-calibrated devices. Besides, temporal measurements at the picosecond scale were carried out to support the analysis.

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“…On the other hand, from the perspective of organic materials, the less overlap between absorption spectra and photoluminescence (PL) spectra will help reduce the self-absorption attenuation of this material, ensuring the stimulated lasing with low threshold. Therefore, the study on the optical as well as electrical characteristics of organic dyes would be crucial for the realization of electrically driven organic lasers [15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

The energy transfer mechanism of a photoexcited and electroluminescent organic hybrid thin film of blue, green, and red laser dyes

Li¹,

Zhang²,

Zheng³

et al. 2016

Nano Online

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Though optically pumped lasing has been realized for years, electrically pumped lasing has not yet been achieved in organic semiconductor devices. In order to make a better understanding of the laser mechanisms of the organic materials, we prepared organic thin films consisting of three efficient laser dyes of a blue emitter, 4″,4″′-N,vinyl]benzene (DSB), and a red emitter, 4-(dicyanomethylene)-2-t-butyl-6(1,1,7,7-tetramethyljulolidy-l-9-enyl)-4H-pyran (DCJTB) with different doping concentrations for the first time to investigate the cascade energy transfer process. The energy transfer schemes in the co-doped thin films in photoluminescence and electroluminescence have been investigated. The results indicated that the DSB molecules acted as a bridge to deliver energy more effectively from the host (BN) to the guest (DCJTB). Meanwhile, the maximum current efficiency (C E ) and power efficiency (P E ) of the organic light-emitting devices (OLEDs) with the emitting layer of lower doping concentration were 13.5 cd/A and 14.1 lm/W, respectively.

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Temporal response of optically pumped organic semiconductor lasers and its implication for reaching threshold under electrical excitation

Cited by 105 publications

References 21 publications

Plasmonic Sinks for the Selective Removal of Long-Lived States

Plasmonic Sinks for the Selective Removal of Long-Lived States

Gain properties of dye-doped polymer thin films

The energy transfer mechanism of a photoexcited and electroluminescent organic hybrid thin film of blue, green, and red laser dyes

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