Singlet exciton energy transfer in organic solids

Powell, Richard C.; Soos, Z. G.

doi:10.1016/0022-2313(75)90077-0

Cited by 378 publications

(228 citation statements)

References 110 publications

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“…RET is difficult to distinguish from the FRET in steady-state measurements. 52 The small difference between the calculated and experimental quantum yields (see Figure 3d) could probably be explained as due to the presence of RET. However, investigation of the transient photoluminescence kinetics and modeling as a function of controlled stacking strongly suggests that the dominant exciton transport mechanism is based on nonradiative exciton transfer (i.e., homo-FRET).…”

Section: Resultsmentioning

confidence: 94%

Stacking in Colloidal Nanoplatelets: Tuning Excitonic Properties

et al. 2014

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Cataloged from PDF version of article.Colloidal semiconductor quantum wells, also commonly known as nanoplatelets (NPLs), have arisen among the most promising materials for light generation and harvesting applications. Recently, NPLs have been found to assemble in stacks. However, their emerging characteristics essential to these applications have not been previously controlled or understood. In this report, we systematically investigate and present excitonic properties of controlled column-like NPL assemblies. Here, by a controlled gradual process, we show that stacking in colloidal quantum wells substantially increases exciton transfer and trapping. As NPLs form into stacks, surprisingly we find an order of magnitude decrease in their photoluminescence quantum yield, while the transient fluorescence decay is considerably accelerated. These observations are corroborated by ultraefficient Forster resonance energy transfer (FRET) in the stacked NPLs, in which exciton migration is estimated to be in the ultralong range (>100 nm). Homo-FRET (i.e., FRET among the same emitters) is found to be ultraefficient, reaching levels as high as 99.9% at room temperature owing to the close-packed collinear orientation of the NPLs along with their large extinction coefficient and small Stokes shift, resulting in a large Forster radius of similar to 13.5 nm. Consequently, the strong and long-range homo-FRET boosts exciton trapping in nonemissive NPLs, acting as exciton sink centers, quenching photoluminescence from the stacked NPLs due to rapid nonradiative recombination of the trapped excitons. The rate-equation-based model, which considers the exciton transfer and the radiative and nonradiative recombination within the stacks, shows an excellent match with the experimental data. These results show the critical significance of stacking control in NPL solids, which exhibit completely different signatures of homo-FRET as compared to that in colloidal nanocrystals due to the absence of inhomogeneous broadening

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Section: Resultsmentioning

confidence: 94%

Stacking in Colloidal Nanoplatelets: Tuning Excitonic Properties

et al. 2014

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“…This equation has been shown to describe well the diffusion-mediated quenching in organic crystals 12 and is applicable to P3HT:PCBM blends because they show a spatial periodicity of P3HT and PCBM domains. 5 This is verified by the asymptotic quenching kinetics being exponential as the second term in Eq.…”

Section: Dynamics Of Fluorescence Quenchingmentioning

confidence: 95%

Probing the nanoscale phase separation in binary photovoltaic blends of poly(3-hexylthiophene) and methanofullerene by energy transfer

2009

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Images reproduced with permission of Michael GrätzelArticles published in this issue include: PERSPECTIVES:Introducing a dark reaction to photochemistryPhotocatalytic hydrogen from [FeFe] The generation of charge carriers in organic photovoltaic devices requires exciton diffusion to an interface of electron donor and acceptor materials, where charge separation occurs. We report a time resolved study of fluorescence quenching in films of poly(3-hexylthiophene) containing a range of fractions of the electron acceptor [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). We show that energy transfer from P3HT to PCBM helps to bring excitons to the interface, where they dissociate into charge carriers. Fluorescence quenching in blends with ≤50 wt% of PCBM is controlled by exciton diffusion in P3HT. This allows us to estimate the average size of PCBM domains to be about 9 nm in the 1:1 blend. The implications for polymer solar cells are discussed.

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“…Along with near-field hopping, the emission and reabsorption of a photon is another mechanism that can give rise to energy transport. This radiative form of energy transport is often difficult to distinguish from exciton hopping in exciton transport measurements, as has been discussed by Powell et al 32 In particular, photon emission followed by reabsorption (ERA) is itself a random walk process due to the randomization of the photon direction with each emission event.…”

Section: Article Nature Communications | Doi: 101038/ncomms4646mentioning

confidence: 99%

Visualization of exciton transport in ordered and disordered molecular solids

et al. 2014

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Transport of nanoscale energy in the form of excitons is at the core of photosynthesis and the operation of a wide range of nanostructured optoelectronic devices such as solar cells, lightemitting diodes and excitonic transistors. Of particular importance is the relationship between exciton transport and nanoscale disorder, the defining characteristic of molecular and nanostructured materials. Here we report a spatial, temporal and spectral visualization of exciton transport in molecular crystals and disordered thin films. Using tetracene as an archetype molecular crystal, the imaging reveals that exciton transport occurs by random walk diffusion, with a transition to subdiffusion as excitons become trapped. By controlling the morphology of the thin film, we show that this transition to subdiffusive transport occurs at earlier times as disorder is increased. Our findings demonstrate that the mechanism of exciton transport depends strongly on the nanoscale morphology, which has wide implications for the design of excitonic materials and devices.

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Singlet exciton energy transfer in organic solids

Cited by 378 publications

References 110 publications

Stacking in Colloidal Nanoplatelets: Tuning Excitonic Properties

Stacking in Colloidal Nanoplatelets: Tuning Excitonic Properties

Probing the nanoscale phase separation in binary photovoltaic blends of poly(3-hexylthiophene) and methanofullerene by energy transfer

Visualization of exciton transport in ordered and disordered molecular solids

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