Entropic Mixing Allows Monomeric‐Like Absorption in Neat BODIPY Films

Schäfer, Clara; Mony, Jürgen; Olsson, Thomas; Börjesson, Karl

doi:10.1002/chem.202002463

Cited by 9 publications

(18 citation statements)

References 46 publications

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“…As in numerous other BODIPY derivatives and previous studies of BODIPY-R, at this concentration the dye exhibits sufficient oscillator strength to undergo strong light-matter coupling within metallic and dielectric cavities (Figure 1b). 42,61,[68][69][70][71][72] Figure 1c shows typical angleresolved reflectivity from such a DBR cavity. In addition to the strong dispersion of the stop band, we resolve distinct local minima in the reflectivity surrounding the bare 0-0 vibronic peak at 630 nm.…”

Section: Methodsmentioning

confidence: 99%

Untargeted effects in organic exciton–polariton transient spectroscopy: A cautionary tale

Renken

Pandya

Georgiou

et al. 2021

The Journal of Chemical Physics

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Strong light-matter coupling to form exciton-and vibropolaritons is increasingly touted as a powerful tool to alter the fundamental properties of organic materials. It is proposed that these states and their facile tunability can be used to rewrite molecular potential energy landscapes and redirect photophysical pathways, with applications from catalysis to electronic devices. Crucial to their photophysical properties is the exchange of energy between coherent, bright polaritons and incoherent dark states. One of the most potent tools to explore this interplay is transient absorption/reflectance spectroscopy. Previous studies have revealed unexpectedly long lifetimes of the coherent polariton states, for which there is no theoretical explanation. Applying these transient methods to a series of strong-coupled organic microcavities, we recover similar long-lived spectral effects. Based on transfer-matrix modelling of the transient experiment, we find that virtually the entire photoresponse results from photoexcitation effects other than the generation of polariton states. Our results suggest that the complex optical properties of polaritonic systems make them especially prone to misleading optical signatures, and that more challenging high-time-resolution measurements on high-quality microcavities are necessary to uniquely distinguish the coherent polariton dynamics.

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Section: Methodsmentioning

confidence: 99%

Untargeted effects in organic exciton–polariton transient spectroscopy: A cautionary tale

Renken

Pandya

Georgiou

et al. 2021

The Journal of Chemical Physics

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“…This reaction was performed under N 2 -atmosphere, following the reported procedure. 45 The products of this reaction will, in the following, be called R-SCP-NH-αCOH, where R stands for the residue in para position on the arylhalide, SCP denotes the Suzuki coupling product, NH denotes the free Pyrrole NH, and αCOH stands for the formylation in the second α position of the pyrrole. The procedure is described taking H-SCP-NH-αCOH as an example.…”

Section: Experimental Sectionmentioning

confidence: 99%

“…This reaction was performed under N 2 atmosphere, following the reported procedure. 45 Taking the synthesis of CN-CN-BODIPY as an example,…”

Section: Experimental Sectionmentioning

confidence: 99%

Effect of the Aza-N-Bridge and Push–Pull Moieties: A Comparative Study between BODIPYs and Aza-BODIPYs

et al. 2022

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In the field of fluorescent dyes, difluoroboron-dipyrromethenes (BODIPY) have a highly respected position. To predict their photophysical properties prior to synthesis and therefore to successfully design molecules specifically for one’s needs, a solid structure–function understanding based on experimental observations is vital. This work delivers a photophysical evaluation of BODIPY and aza-BODIPY derivatives equipped with different electron-withdrawing/-donating substituents. Using combinatorial chemistry, pyrroles substituted with electron-donating/-withdrawing substituents were condensed together in two different manners, thus providing two sets of molecules. The only difference between the two sets is the bridging unit providing a so far lacking comparison between BODIPYs and aza-BODIPYs structural homologues. Replacing the meso -methine bridge with an aza-N bridge results in a red-shifted transition and considerably different, temperature-activated, excited-state relaxation pathways. The effect of electron-donating units on the absorption but not emission for BODIPYs was suppressed compared to aza-BODIPYs. This result could be evident in a substitution pattern-dependent Stokes shift. The outlook of this study is a deeper understanding of the structure–optics relationship of the (aza)-BODIPY-dye class, leading to an improvement in the de novo design of tailor-made molecules for future applications.

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“… 10 − 12 Another method is entropic mixing, where chromophores with different alkyl side chains are blended together, resulting in a stronger glass-forming capability. 13 − 15 This attempt of reducing the π–π-interactions and therefore the aggregation is favorable for applications where the molecular size and weight play a major role. However, it is sometimes difficult to completely remove the formation of detrimental aggregation, and in such cases, a higher degree of control of excited-state relaxation pathways is crucial to prevent photon emission losses.…”

Section: Introductionmentioning

confidence: 99%

Interplay between Polaritonic and Molecular Trap States

Mony

Schäfer

et al. 2022

J. Phys. Chem. C

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Strong exciton–photon coupling exhibits the possibility to modify the photophysical properties of organic molecules. This is due to the introduction of hybrid light–matter states, called polaritons, which have unique physical and optical properties. Those strongly coupled systems provide altered excited-state dynamics in comparison to the bare molecule case. In this study, we investigate the interplay between polaritonic and molecular trap states, such as excimers. The molecules used in this study show either prompt or delayed emission from trap states. For both cases, a clear dependency on the exciton–photon energy tuning was observed. Polaritonic emission gradually increased with a concurrent removal of aggregation-induced emission when the systems were tuned toward lower energies. For prompt emission, it is not clear whether the experimental results are best explained by a predominant relaxation toward the lower polariton after excitation or by a direct excimer to polariton transition. However, for the delayed emission case, trap states are formed on the initially formed triplet manifold, making it evident that an excimer-to-polariton transition has occurred. These results unveil the possibility to control the trap state population by creating a strongly coupled system, which may form a mitigation strategy to counteract detrimental trap states in photonic applications.

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Entropic Mixing Allows Monomeric‐Like Absorption in Neat BODIPY Films

Cited by 9 publications

References 46 publications

Untargeted effects in organic exciton–polariton transient spectroscopy: A cautionary tale

Untargeted effects in organic exciton–polariton transient spectroscopy: A cautionary tale

Effect of the Aza-N-Bridge and Push–Pull Moieties: A Comparative Study between BODIPYs and Aza-BODIPYs

Interplay between Polaritonic and Molecular Trap States

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