371193-08-7Relevant academic research and scientific papers
Functionalized tetrafluorenylethylene-type chromophores: Synthesis, two-photon absorption and effective optical power-limiting properties in the visible-to-near IR region
Lin, Tzu-Chau,Lee, Ying-Hsuan,Huang, Bor-Rong,Tsai, Ming-Yu,Lin, Jhe-Yi
, p. 325 - 333 (2016)
A series of novel multipolar fluorophores based on tetra-substituted olefinic scaffold using functionalized fluorenyl and indenofluorenyl units as the aryl substituents has been synthesized and investigated for their two-photon-related properties in the f
Fluorenone-containing polyfluorenes and oligofluorenes: Photophysics, origin of the green emission and efficient green electroluminescence
Kulkarni, Abhishek P.,Kong, Xiangxing,Jenekhe, Samson A.
, p. 8689 - 8701 (2004)
A series of four new statistical copolymers of 9,9-dihexylfluorene and 9-fluorenone with well-defined structures and a new fluorene-fluorenone-fluorene trimer model compound were synthesized and used to investigate the photophysics, origin of the green emission, and electroluminescence of this class of light-emitting materials. We show that the new oligofluorene trimer with a central fluorenone moiety is an excellent model of the green-emitting chromophore in polyfluorenes. From systematic studies of the steady-state photoluminescence (PL) and PL decay dynamics of solutions of the fluorenone-containing copolymers and oligomer and thin films of the copolymers, we show that the controversial 535-nm green emission band originates from the fluorenone defects in single-chain polyfluorenes and not from intermolecular aggregates or excimers. The green emission, centered at 535 nm, was observed in dilute toluene solutions of all fluorenone-containing copolymers and oligomer; it was long-lived with a single-exponential PL lifetime of a??5 ns, compared to a lifetime of 240-400 ps for the blue emission. The PL decay dynamics of the 535-nm emission from thin films of all copolymers was also well-described by a single-exponential lifetime of 5-6 ns. The observed increased intensity of the green emission with increased intermolecular interactions in solution or solid state can be explained by the increased excitation energy transfer from fluorene segments to the fluorenone moieties. Bright green electroluminescence (EL) centered at 535 nm was achieved from single-layer copolymer light-emitting diodes (LEDs), ITO/PEDOT/copolymer/Al, with luminances of 1600-3340 cd/m 2 that varied with fluorenone content. The EL data suggest that the fluorene-fluorenone copolymers are very promising materials for green LEDs.
Synthesis and properties of monodisperse oligofluorene-funcfionalized truxenes: Highly fluorescent star-shaped architectures
Kanibolotsky, Alexander L.,Berridge, Rory,Skabara, Peter J.,Perepichka, Igor F.,Bradley, Donal D. C.,Koeberg, Mattijs
, p. 13695 - 13702 (2004)
This paper describes the strategy toward novel monodisperse, well-defined, star-shaped oligofluorenes with a central truxene core and from monofluorene to quaterfluorene arms. Introduction of solubilizing n-hexyl groups at both fluorene and truxene moieties results in highly soluble, intrinsically two-dimensional nanosized macromolecules T1-T4. The radius for the largest oligomer of ca. 3.9 nm represents one of the largest known star-shaped conjugated systems. Cyclic voltammetry experiments reveal reversible or quasi-reversible oxidation and reduction processes (Eox = +0.74 to 0.80 V, Ered = -2.66 to 2.80 eV vs Fc/Fc+), demonstrating excellent electrochemical stability toward both p- and n-doping, while the band gaps of the oligomers are quite high (Egcv = 3.20-3.40 eV). Close band gaps of 3.05-3.29 eV have been estimated from the electron absorption spectra. These star-shaped macromolecules demonstrate good thermal stability (up to 400-420°C) and improved glass transition temperatures with an increase in length of the oligofluorene arms (from Tg = 63°C for T1 to 116°C for T4) and show very efficient blue photoluminescence (λPL = 398-422 nm) in both solution (ΦPL = 70-86%) and solid state (ΦPL = 43-60%). Spectroelectrochemical experiments reveal that compounds T1-T4 are stable electrochromic systems which change their color reversibly from colorless in the neutral state (～340-400 nm) to colored (from red to purple color; ～500-600 nm) in the oxidized state.
Efficient Color-Tunable Copper(I) Complexes and Their Applications in Solution-Processed Organic Light-Emitting Diodes
So, Gary Kwok-Ming,Cheng, Gang,Wang, Jian,Chang, Xiaoyong,Kwok, Chi-Chung,Zhang, Hongxing,Che, Chi-Ming
supporting information, p. 1490 - 1498 (2017/07/11)
A series of dppnc- and neocuproine-based CuI complexes (dppnc=7,8-bis(diphenylphosphino)-7,8-dicarba-nido-undecaborate) are synthesized and the emission color of these CuI complexes can be tuned from green to deep red via rational modification of the neocuproine ligand structure. The molecular structures of the emissive CuI complexes, Cu(dppnc)-G (green emitting), Cu(dppnc)-Y (yellow emitting), and Cu(dppnc)-R (red emitting), are characterized and their electronic structures and related transition properties are elucidated by photo-physical and computational (density functional theory) studies. The calculation results suggest that thermally activated delayed fluorescence (TADF) is the emission mechanism for these CuI complexes. Efficient solution-processed green-, yellow-, and red-emitting OLEDs are fabricated based on the emissive complexes as the dopants. High external quantum efficiency (EQE) of 15.20 % and current efficiency of 48.15 cd A?1 at 1000 cd m?2 are achieved in the green-emitting device with Cu(dppnc)-G. A maximum EQE of 10.17 %, CIE coordinates of (0.61, 0.38) and a maximum electroluminescent peak of 631 nm are achieved in the red device based on Cu(dppnc)-R.
Synthesis and fluorescent properties of conjugated copolymers containing maleimide and fluorene units at the main chain
Nakamura, Munetoshi,Yamabuki, Kazuhiro,Oishi, Tsutomu,Onimura, Kenjiro
, p. 4945 - 4956 (2013/11/06)
Yamamoto or Suzuki-Miyaura coupling polymerizations of 2,3-diiodo-N- cyclohexylmaleimide with fluorene derivatives (2,7-dibromo-9,9′- dihexylfluorene and 9,9′-dihexylfluorene-2,7-diboronic acid) were carried out. The number-average molecular weights (Mn) of the resulting copolymers were 2600-3500 by gel permeation chromatography analysis. The fluorescence emission of the alternating copolymer showed the emission maxima at 551 nm in THF. On the other hand, the random copolymers showed the bimodal emission peaks at 418-420 and 555-557 nm region, respectively. The fluorescence peaks of the random copolymers on the long wavelength region (555-557 nm) were attributed to the conjugated neighboring N-cyclohexylmaleimide-9,9′- dihexylfluorene units in the polymer main chain. Furthermore, the copolymers exhibited the fluorescence solvatochromism by the difference of the polarity of solvents. The alternating and random copolymers showed the different fluorescence solvatochromism, and the emission colors are distinguishable by the naked eye, respectively. Copyright
Oligofluorenes as polymeric model compounds for providing insight into the triplets of ketone and ketylimine derivatives
Robert, Patricia,Bolduc, Andreanne,Skene, W. G.
, p. 9305 - 9314,10 (2020/08/24)
A series of oligofluorenes ranging between one and three repeating units were prepared as structurally well-defined representative models of polyfluorenes. The photophysics of the oligofluorene models were investigated both by laser flash photolysis and steady-state fluorescence. The effects of the ketone and ketylimine functional groups in the 9-position on the photophysical properties, notably the triplet quantum yield (ΦTT) by intersystem crossing and the absolute fluorescence quantum yields (Φfl), were investigated. The singlet depletion method was used to determine both the ΦTT and molar absorption coefficients of the observed triplets (εTT). Meanwhile, the absolute Φfl were determined using an integrating sphere. It was found that both the ketone and ketylimine substituents and the degree of oligomerization contributed to quenching the oligofluorene fluorescence. For example, the Φfl was quenched 5-fold with the ketylimine and ketone substituents for the bifluorenyl derivatives compared to their corresponding 9,9-dihexyl bifluorenyl counterparts. Meanwhile, the Φfl quenching increased 14 times with the trifluorenyl ketone and ketylimine derivatives. Measured ΦTT values ranged between 22 and 43% for the difluorenyl derivatives with εTT on the order of 13 000 cm-1 M-1. The ΦTT decreased to TT when the degree of oligomerization was increased to 3. A new fluorescence emission at 545 nm formed at low temperatures for the ketone and ketylimine oligofluorene derivatives. The emission intensity was dependent on the temperature, and it disappeared at room temperature.
Photophysical, electrochemical, and crystallographic investigation of conjugated fluoreno azomethines and their precursors
Guarin, Sergio Andres Perez,Dufresne, Stephane,Tsang, Derek,Sylla, Assa,Skene
, p. 2801 - 2811 (2008/09/17)
The photophysical investigation of amino- and aldehyde-substituted fluorenes revealed that these compounds are not only highly fluorescent, but dissipation of their singlet excited energy occurs by a combination of nonradiative means involving intersystem crossing (ISC) and internal conversion (IC). Quantification of the triplet state formed by ISC was possible by laser-flash photolysis (LFP). The efficiency by which this manifold was populated varied between 10 and 40% depending on the fluorene substitution. Condensation of these aldehyde and amine precursors yielded conjugated thiopheno azomethines with robust covalent bonds. Fluorescence of the azomethine fluorene derivatives was reduced relative to their precursors while the degree of IC remained unchanged. Deactivation of the singlet excited state occurred predominately by ISC and the resulting triplet state was rapidly and efficiently quenched by energy transfer by the azomethine linkage. Cyclic voltammetry of the fluoreno azomethines showed both oxidation and reduction processes, and the measured redox potentials and the band-gaps are lower than a bisfluorene analogue. The fluoreno azomethine LUMO energy levels are sufficiently low, making them compatible with common cathodes, therefore eliminating the use of an electron-injection layer. The Royal Society of Chemistry 2007.
Porphyrin, phthalocyanine and porphyrazine derivatives with multifluorenyl substituents as efficient deep-red emitters
Barker, Carl A.,Zeng, Xianshun,Bettington, Sylvia,Batsanov, Andrei S.,Bryce, Martin R.,Beeby, Andrew
, p. 6710 - 6717 (2008/03/14)
The synthesis and photophysical properties are described for a series of porphyrin, phthalocyanine and pyrazinoporphyrazine derivatives which bear four or eight peripheral fluorenyl substituents as antennae. Representative examples are 5,10,15,20-tetra(9,9-dihexyl-9H-fluoren-2-yl)porphyrin (2), 5,10,15,20-tetrakis[4-(9,9-dihexyl-9H-fluoren-2-yl)phenyl]porphyrin (3), 2,3,9,10,16,17,23,24-octakis(9,9-dihexyl-9H-fluoren-2-yl)-29H, 31H-phthalocyanine (8) and 2,3,9,10,16,17,-23,24-octakis[4-(9,9-dihexyl-9tf- fluoren-2-yl)phenyl]-29H31H-tetrapyrazinoporphyrazine (9). Palladiummediated Suzuki-Miyaura cross-coupling reactions have been key steps for attaching the substituents. The compounds are deep-red emitters: λmax(em) = 659 (3), 737 (8) and 684 nm (9). Their absorption and emission spectra, their fluorescence lifetimes and quantum yields are correlated with the structures of the macrocycles and the substituents. The solution fluorescence quantum yields of porphyrin derivatives substituted with fluorene (2-4) and terphenyl substituents (7) (Φf = 0.21-0.23) are approximately twice that of tetraphenylporphyrin. For phthalocyanine derivative 8, Φf was very high (0.88). Specific excitation of the fluorene units of 8 produced emission from both of them (λmax = 480nm) and also from the phthalocyanine core (λmax = 750 nm), indicating a competitive rate of energy transfer and radiative decay of the fluorenes. Organic light-emitting devices (OLEDs) were made by spincoating techniques by using a polyspirobifluorene (PSBF) copolymer as the host blended with 3 (5 wt. % ) in the configuration ITO/PEDOT:PSS/PSBF copolymer:3/Ca/Al. Deep-red emission (λmax= 663nm; CIE coordinates x = 0.70, y = 0.27) was observed with an external quantum efficiency of 2.5 % (photons/electron) (at 7.5 mA cm-2), a low turn-on voltage and high emission intensity (luminance) of 5500 cdm-2 (at 250 mA/m-2).
Dibenzothiophene-S,S-dioxide-fluorene co-oligomers. Stable, highly-efficient blue emitters with improved electron affinity
Perepichka, Irene I.,Perepichka, Igor F.,Bryce, Martin R.,Palsson, Lars-Olof
, p. 3397 - 3399 (2007/10/03)
Incorporation of dibenzothiophene-S,S-dioxide units into conjugated fluorene oligomers changes the frontier orbital energy levels and presents an effective way to increase the electron affinity of these materials, which are highly fluorescent with bright blue emission in both solution and the solid state. The Royal Society of Chemistry 2005.
Monodisperse fluorene oligomers exhibiting strong dipolar coupling interactions
Anemian, Remi,Mulatier, Jean-Christophe,Andraud, Chantal,Stephan, Olivier,Vial, Jean-Claude
, p. 1608 - 1609 (2007/10/03)
Well-defined fluorene oligomers (n = 1 to 6) were prepared step by step using Suzuki and Yamamoto couplings, while absorption and photoluminescence properties evidenced very large dipolar coupling interactions between fluorene moieties.
