Phosphorescence superradiance in a Pt-containing<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>π</mml:mi></mml:math>-conjugated polymer

Khachatryan, Bagrat; Nguyen, Tho Duc; Vardeny, Z. Valy; Ehrenfreund, E.

doi:10.1103/physrevb.86.195203

Cited by 14 publications

(15 citation statements)

References 31 publications

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“…The FL (PH) band is assigned to transitions from the lowest singlet (triplet) excited state, S 1 (T 1 ) into the ground state, S 0 (or 1 A g )12. The PH 0–0 line is much narrower than the 0–0 FL band and has been recently interpreted as due to super-radiance emission13. The intense vibronic side-bands observed in the triplet emission spectrum result from the large displacement between the S 0 and T 1 optimal geometries14.…”

Section: Resultsmentioning

confidence: 99%

Ultrafast intersystem-crossing in platinum containing π-conjugated polymers with tunable spin-orbit coupling

Sheng

Singh

Alessio

et al. 2013

Sci Rep

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The development of efficient organic light-emitting diodes (OLED) and organic photovoltaic cells requires control over the dynamics of spin sensitive excitations. Embedding heavy metal atoms in π-conjugated polymer chains enhances the spin-orbit coupling (SOC), and thus facilitates intersystem crossing (ISC) from the singlet to triplet manifolds. Here we use various nonlinear optical spectroscopies such as two-photon absorption and electroabsorption in conjunction with electronic structure calculations, for studying the energies, emission bands and ultrafast dynamics of spin photoexcitations in two newly synthesized π-conjugated polymers that contain intrachain platinum (Pt) atoms separated by one (Pt-1) or three (Pt-3) organic spacer units. The controllable SOC in these polymers leads to a record ISC time of <~1 ps in Pt-1 and ~6 ps in Pt-3. The tunable ultrafast ISC rate modulates the intensity ratio of the phosphorescence and fluorescence emission bands, with potential applications for white OLEDs.

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Section: Resultsmentioning

confidence: 99%

Ultrafast intersystem-crossing in platinum containing π-conjugated polymers with tunable spin-orbit coupling

Sheng

Singh

Alessio

et al. 2013

Sci Rep

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“…In an organic quaterthiophene semiconductor whose molecules are arranged in H-aggregate fashion, time-resolved photoluminescence measurements showed that the radiative lifetime had a linear correlation with the inverse of the number of the coherently emitting dipoles, i.e., τ rad ∝ 1/N [102]. More recently, phosphorescence SR was demonstrated in heavy-metal-containing π-conjugated polymers, as a result of the significant spinorbit interaction provided by the large atomic number elements [100]. These experiments on cooperative emission from polymers and molecular crystals have also been discussed using the theory of SR for Frenkel excitons [104].…”

Section: B Molecular Aggregates and Crystalsmentioning

confidence: 99%

“…Cooperative spontaneous emission processes have also been investigated in molecular solids, such as molecular aggregates and crystals, including Jaggregates [96,97], LH-2 photosynthetic antenna complexes [98], π-conjugated polymer thin films [99,100], H-aggregates [101,102], and tetracene thin films and nanoaggregates [103]. In all these studies, accelerated radiative decay was observed and attributed to cooperative emission, although SF, in the form observed in atomic systems (Section II) and molecular centers in crystals (Section III A), has not been reported and some of the reported results and claims remain controversial.…”

Section: B Molecular Aggregates and Crystalsmentioning

confidence: 99%

Dicke superradiance in solids [Invited]

et al. 2016

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Recent advances in optical studies of condensed matter systems have led to the emergence of a variety of phenomena that have conventionally been studied in the realm of quantum optics. These studies have not only deepened our understanding of light-matter interactions but also introduced aspects of many-body correlations inherent in optical processes in condensed matter systems. This article is concerned with the phenomenon of superradiance (SR), a profound quantum optical process originally predicted by Dicke in 1954. The basic concept of SR applies to a general N -body system where constituent oscillating dipoles couple together through interaction with a common light field and accelerate the radiative decay of the whole system. Hence, the term SR ubiquitously appears in order to describe radiative coupling of an arbitrary number of oscillators in many situations in modern science of both classical and quantum description. In the most fascinating manifestation of SR, known as superfluorescence (SF), an incoherently prepared system of N inverted atoms spontaneously develops macroscopic coherence from vacuum fluctuations and produces a delayed pulse of coherent light whose peak intensity ∝ N 2 . Such SF pulses have been observed in atomic and molecular gases, and their intriguing quantum nature has been unambiguously demonstrated. In this review, we focus on the rapidly developing field of research on SR phenomena in solids, where not only photon-mediated coupling (as in atoms) but also strong Coulomb interactions and ultrafast scattering processes exist. We describe SR and SF in molecular centers in solids, molecular aggregates and crystals, quantum dots, and quantum wells. In particular, we will summarize a series of studies we have recently performed on semiconductor quantum wells in the presence of a strong magnetic field. In one type of experiment, electron-hole pairs were incoherently prepared, but a macroscopic polarization spontaneously emerged and cooperatively decayed, emitting an intense SF burst. In another type of experiment, we observed the SR decay of coherent cyclotron resonance of ultrahigh-mobility two-dimensional electron gases, leading to a decay rate that is proportional to the electron density. These results show that cooperative effects in solid-state systems are not merely small corrections that require exotic conditions to be observed; rather, they can dominate the nonequilibrium dynamics and light emission processes of the entire system of interacting electrons.

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“…The PL ratio has also been used to justify the ultra-large coherence lengths measured in practically defect-free polyacetylene chains, also referred to as quantum wires [34,35]; to determine N coh in polyacenes crystals [31,36] and dinaptho-thieno-thiophene (DNTT) crystals [37]; and to monitor coherence in a phosphorescent Pt-containing polymer. [38] In this work we extend our analysis of the PL ratio to include aggregates with significant intermolecular charge transfer. This is particularly relevant for π-stacked geometries where nearest neighbors are typically less than 4 Angstroms apart.…”

Section: Introductionmentioning

confidence: 98%

Determining the spatial coherence of excitons from the photoluminescence spectrum in charge-transfer J-aggregates

Hestand

Spano

2016

Chemical Physics

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The importance of spatial coherence in energy and charge transfer processes in biological systems and photovoltaic devices has been hotly debated over the past several years. While larger spatial coherences are thought to benefit transport, a clear correlation has yet to be established, partly because a simple and accurate measure of the coherence length has, for the most part, remained elusive. Previously, it was shown that the number of coherently connected chromophores, Coh N , can be determined directly from the ratio ( R S ) of the 0-0 and 0-1 vibronic line strengths in the photoluminescence (PL) spectrum. The relation,where 2 0 λ is the associated Huang-Rhys parameter, was derived in the Frenkel exciton limit. Here, it is shown that R S remains a highly accurate measure of coherence for systems characterized by significant charge transfer interactions (e.g. conjugated π-stacked systems). The only requirement is that the exciton band curvature must be positive, as in a J-aggregate.

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Phosphorescence superradiance in a Pt-containingπ-conjugated polymer

Cited by 14 publications

References 31 publications

Ultrafast intersystem-crossing in platinum containing π-conjugated polymers with tunable spin-orbit coupling

Ultrafast intersystem-crossing in platinum containing π-conjugated polymers with tunable spin-orbit coupling

Dicke superradiance in solids [Invited]

Determining the spatial coherence of excitons from the photoluminescence spectrum in charge-transfer J-aggregates

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