A “Cyanine−Cyanine” Salt Exhibiting Photovoltaic Properties

Bouit, Pierre‐Antoine; Rauh, Daniel; Neugebauer, Stefan; Delgado, Juan Luis; Piazza, Emmanuel Di; Rigaut, Stéphane; Maury, Olivier; Andraud, Chantal; Dyakonov, Vladimir; Martı́n, Nazario

doi:10.1021/ol901764t

Cited by 71 publications

(53 citation statements)

References 22 publications

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“…To develop optical quality films suitable for integration into SOH devices, we doped an amorphous polycarbonate (APC), a highly processable host polymer with a sizable refractive index, with an anionic polymethine chromophore based upon the strong electron withdrawing moiety, 4,5,5‐trimethyl‐3‐cyano‐2(5H)‐furanylidenepropane‐dinitrile (TCF), as terminal groups. The TCF polymethine is notably resistant to aggregation‐induced effects based on the similarity of linear absorption spectra of high chromophore density films to those of dilute chromophore solutions 10a. As polymethine dyes are highly polarizable and ionic while the APC host polymer is neutral, the resulting guest‐host films often suffer from significant phase separation due to lack of sufficient solvation energy of the TCF polymethine and its counterion in the polymer matrix.…”

Section: Linear Optical and Thermal Properties Of Tcf Polymethinesmentioning

confidence: 99%

“…The polymethines have been prepared by simple ion exchange reactions between the aromatic cation containing salts and the sodium salt of TCF based anionic polymethines, as shown in Scheme S1 in the Supporting Information, according to the method reported in literature 10b. A polymethine with an aliphatic counterion ( AJBC 1721 ) was also prepared as a model compound for comparison.…”

Section: Linear Optical and Thermal Properties Of Tcf Polymethinesmentioning

confidence: 99%

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High‐Optical‐Quality Blends of Anionic Polymethine Salts and Polycarbonate with Enhanced Third‐Order Non‐linearities for Silicon‐Organic Hybrid Devices

Liu

Kim

et al. 2012

Advanced Materials

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Considerable effort has been devoted to enabling all-optical signal processing (AOSP) for future communications systems with signifi cantly increased operational bandwidth. [ 1 ] Suitable materials for AOSP must exhibit ultrafast third-order nonlinear optical (NLO) response, as well as low linear and nonlinear optical loss, to achieve very high speed optical switching or modulation (100 Gbit/s or beyond). [ 1b ] While silicon is an attractive candidate material for AOSP due to its ease of chipscale photonic integration, its third-order NLO response is accompanied by parasitic non-linear absorption losses and longlived free carrier effects. [ 1c , 2 ] Recently, several groups have demonstrated silicon-organic hybrid (SOH) devices for AOSP with bandwidths exceeding 100 Gbit/s by integrating organic materials with silicon slot waveguides, [ 3 , 4 ] effectively combining the large non-linearities of organic materials with the extraordinary modal fi eld concentrations of silicon waveguides. Nonetheless, development of organic materials suitable for device integration which possess large non-linearities and small optical losses in the telecommunications region remains a challenge.Polymethine dyes [ 5 ] are an intriguing class of conjugated organic molecules for AOSP applications: the π -electrons along the conjugated backbone can be polarized easily, resulting in a large negative third-order molecular polarizability ( γ ) [ 6 ] and the electronic absorption bands are usually very narrow with sharp low energy band edges, which can be useful in reducing linear absorption losses at the desired operational wavelengths. Furthermore, polymethine dyes terminated with selenopyrylium end groups were recently found to exhibit large magnitudes of Re( γ ) at telecommunications wavelengths while also suppressing non-linear absorption such that excellent two-photon fi gures-of-merit (FOMs) (i.e., | Re( γ )/Im( γ ) | ) were achieved. [ 7 ] If the molecular third-order non-linearities of polymethine chromophores can be translated into macroscopic nonlinearities (e.g., χ (3) ) in high-number-density chromophoric materials, such materials could enable high-performance AOSP devices. However, there are several major challenges that need to be overcome in order to effectively translate the large γ into a large χ (3) . At high molecular number densities, the intrinsic optical properties of polymethine dyes can be deleteriously affected by intermolecular interactions resulting in, for example, aggregation [ 8 ] and ion-pairing effects, [ 9 ] both of which can lead to an increase in absorptive optical loss (linear and non-linear) at AOSP wavelengths. To mitigate the potential absorptive loss from these interactions, we have employed polymer guest-host approach to develop processable fi lms with high chromophore number density. However, with this approach, phase separation of polymethine salts in a host polymer can also lead to undesirable scattering and optical loss.Here, we report on the development of a miscible polymethine salt, polyme...

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Section: Linear Optical and Thermal Properties Of Tcf Polymethinesmentioning

confidence: 99%

Section: Linear Optical and Thermal Properties Of Tcf Polymethinesmentioning

confidence: 99%

High‐Optical‐Quality Blends of Anionic Polymethine Salts and Polycarbonate with Enhanced Third‐Order Non‐linearities for Silicon‐Organic Hybrid Devices

Liu

Kim

et al. 2012

Advanced Materials

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“…As described for similar cationic heptamethines, 1 reveals an amphoteric redox character with a completely reversible one-electron reduction process at À1.02 V followed by a nonreversible reduction process at À1.94 V versus the ferrocene/ferricenium couple. [15] Oneelectron oxidation processes, on the other hand, are found at + 0.30 V (fully reversible) and + 0.93 V (quasi-reversible). Additionally, in 2, three reversible one-electron reduction processes-all centered on C 60 -were observed at À1.18, À1.52, and À2.07 V ( Figure 2).…”

Section: Electrochemistrymentioning

confidence: 99%

Efficient Utilization of Higher‐Lying Excited States to Trigger Charge‐Transfer Events

Bouit

Spänig

Kuzmanich

et al. 2010

Chemistry A European J

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Several new fullerene-heptamethine conjugates, which absorb as far as into the infrared spectrum as 800 nm, have been synthesized and fully characterized by physicochemical means. In terms of optical and electrochemical characteristics, appreciable electronic coupling between both electroactive species is deduced. The latter also reflect the excited-state features. To this end, time-resolved, transient absorption measurements revealed that photoexcitation is followed by a sequence of charge-transfer events which evolve from higher singlet excited states (i.e., S(2)--fast charge transfer) and the lowest singlet excited state of the heptamethine cyanine (i.e., S(1)--slow charge transfer), as the electron donor, to either a covalently linked C(60) or C(70), as the electron acceptor. Finally, charge transfer from photoexcited C(60)/C(70) completes the charge-transfer sequence. The slow internal conversion within the light-harvesting heptamethine cyanine and the strong electronic coupling between the individual constituents are particularly beneficial to this process.

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“…Our research group has recently described a new organic salt by association of two NIR-absorbing cyanine dyes, which exhibits a good solubility in organic solvents [62] ( Fig. 9.21).…”

Section: Fullerenes For Organic Photovoltaicsmentioning

confidence: 99%