A solvent-free and vacuum-free melt-processing method to fabricate organic semiconducting layers with large crystal size for organic electronic applications

Ribierre, Jean-Charles,Li, Zhao,Liu, Xiao,Lacaze, Emmanuelle,Heinrich, Benoî,t,Mé,ry, Stephane,Sleczkowski, Piotr,Xiao, Yiming,Lafolet, Fré,dé,ric,Hashizume, Daisuke,Aoyama, Tet The Royal Society of Chemistry 2019 Journal of materials chemistry. C, Materials for o Vol.7 No.11

<P>We report on an improved melt-processing method to prepare organic semiconducting layers with large crystal size and enhanced charge carrier mobilities. The organic compound used in this work is a solution-processable oligo(<I>p</I>-phenylene vinylene) derivative substituted at both ends with pyrene moieties. Accurate control of the temperature during the recrystallization of this compound from the melt enables the formation of large single crystal monodomains in thin films. The melt-processed organic layer shows higher mobilities in transistor configuration than in spin-coated films, which can be attributed to the presence of large-size crystalline monodomains as evidenced by X-ray diffraction measurements. We also investigated the photophysical properties of this material in spin-coated and melted films and found an increase of the photoluminescence quantum yield with the size of the crystals in the organic layer. The advantage of this method over the spin coating also allowed observation of amplified spontaneous emission that was only achieved in the melted film due to its improved luminescence efficiency. Overall, this study demonstrates a simple and versatile method, which does not require the use of any solvent and vacuum, to fabricate organic layers with large crystal size, suitable for the realization of organic electronic and light-emitting devices.</P>

Borondifluoride complexes of hemicurcuminoids as bio-inspired push–pull dyes for bioimaging

Kim, Eunsun,Felouat, Abdellah,Zaborova, Elena,Ribierre, Jean-Charles,Wu, Jeong Weon,Senatore, Sé,bastien,Matthews, Cé,dric,Lenne, Pierre-Franç,ois,Baffert, Carole,Karapetyan, Artak,G The Royal Society of Chemistry 2016 Organic & Biomolecular Chemistry Vol.14 No.4

<P>Hemicurcuminoids are based on half of the pi-conjugated backbone of curcuminoids. The synthesis of a series of such systems and their borondifluoride complexes is described. The electrochemical and photophysical properties of difluorodioxaborine species were investigated as a function of the nature of electron donor and acceptor groups appended at either terminal positions of the molecular backbone. The emissive character of these dipolar dyes was attributed to an intraligand charge transfer process, leading to fluorescence emission that is strongly dependent on solvent polarity. Quasi-quantitative quenching of fluorescence in high polarity solvents was attributed to photoinduced electron transfer. These dyes were shown to behave as versatile fluorophores. Indeed, they display efficient two-photon excited fluorescence emission leading to high two-photon brightness values. Furthermore, they form nanoparticles in water whose fluorescence emission quantum yield is less than that of the dye in solution, owing to aggregation-induced fluorescence quenching. When cos7 living cells were exposed to these weakly-emitting nanoparticles, one-and two-photon excited fluorescence spectra showed a strong emission within the cytoplasm that originated from the individual molecules. Dye uptake thus involved a disaggregation mechanism at the cell membrane which restored fluorescence emission. This off-on fluorescence switching allows a selective optical monitoring of those molecules that do enter the cell, which offers improved sensitivity and selectivity of detection for bioimaging purposes.</P>

Blue-Shifting Intramolecular Charge Transfer Emission by Nonlocal Effect of Hyperbolic Metamaterials

Lee, Kwang Jin,Lee, Yeon Ui,Fages, Fré,dé,ric,Ribierre, Jean-Charles,Wu, Jeong Weon,D’Alé,o, Anthony American Chemical Society 2018 NANO LETTERS Vol.18 No.2

<P>Metallic nanostructures permit controlling various photophysical processes by coupling photons with plasmonic oscillation of electrons confined in the tailored nanostructures. One example is hyperbolic metamaterial (HMM) leading to an enhanced spontaneous emission rate of emitters located nearby. Noting that emission in organic molecules is from either pi-pi* or intramolecular charge-transfer (ICT) states, we address here how HMM modifies ICT emission spectral features by comparing them with a spectral shift dependent on the local polarity of the medium. The 7.0 nm blue shift is observed in ICT emission from 4-dicyanomethylene-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran dispersed into a polymer matrix prepared on HMM multilayered structure, while no spectral shift is observed in pi-pi* emission from perylene diimide. In the frame of the Lippert-Mataga formalism, the blue shift is explained by the HMM nonlocal effects resulting from 8% decrease in refractive index and 18% reduction in dielectric permittivity. This phenomenon was also shown in a hemi-curcuminoid borondifluoride dye yielding 15.0 nm blue shift. Such a capability of spectral shift control in films by HMM structure opens new prospects for engineering organic light-emitting devices.</P>

Ethynylene-analogues of hemicurcuminoids: Synthesis and ground- and excited properties of their boron difluoride complexes

Š,tefane, Bogdan,Pož,gan, Franc,Kim, Eunsun,Choi, Eunyoung,Ribierre, Jean-Charles,Wu, Jeong Weon,Ponce-Vargas, Miguel,Le Guennic, Boris,Jacquemin, Denis,Canard, Gabriel,Zaborova, Elena,Fages Applied Science Publishers 2017 Dyes and pigments Vol.141 No.-

<P><B>Abstract</B></P> <P>The synthesis, characterization and (TD)-DFT calculations of the electrochemical and photophysical properties of novel ethynylene-analogues of hemicurcuminoids are described. These dyes are both emissive in solution and in the solid state. While compounds that emit through an efficient charge transfer (CT) state show solvatochromic behaviour associated with low fluorescence quantum yields, those lacking of donor groups show high fluorescence quantum yields of 70–80%, in solution. The latter dyes also present the advantage to emit in the solid state in the visible region with fluorescence quantum yields up to 23%. Their condensed phase spectrum can be bathochromically shifted to the near infrared region (742 nm) by appending a strong donor group.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Synthesis of new fluorophores based on hemicurcuminoid boron difluoride. </LI> <LI> Photophysical study reveals strong emission of the dyes not containing charge transfer states. </LI> <LI> Fluorescence properties of dyes in their condensed phase show aggregation induced emission. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Improvement of the quasi-continuous-wave lasing properties in organic semiconductor lasers using oxygen as triplet quencher

Sandanayaka, Atula S. D.,Zhao, Li,Pitrat, Delphine,Mulatier, Jean-Christophe,Matsushima, Toshinori,Andraud, Chantal,Kim, Ju-Hyung,Ribierre, Jean-Charles,Adachi, Chihaya American Institute of Physics 2016 Applied Physics Letters Vol.108 No.22

Thin reduced graphene oxide interlayer with a conjugated block copolymer for high performance non-volatile ferroelectric polymer memory

Velusamy, D.B.,Kim, R.H.,Takaishi, K.,Muto, T.,Hashizume, D.,Lee, S.,Uchiyama, M.,Aoyama, T.,Ribierre, J.C.,Park, C. Elsevier Science 2014 Organic electronics Vol.15 No.11

Polymer ferroelectric-gate field effect transistors (Fe-FETs) employing ferroelectric polymer thin films as gate insulators are highly attractive as a next-generation non-volatile memory. For minimizing gate leakage current of a device which arises from electrically defective ferroelectric polymer layer in particular at low operation voltage, the materials design of interlayers between the ferroelectric insulator and gate electrode is essential. Here, we introduce a new solution-processed interlayer of conductive reduced graphene oxides (rGOs) modified with a conjugated block copolymer, poly(styrene-block-paraphenylene) (PS-b-PPP). A FeFET with a solution-processed p-type oligomeric semiconducting channel and ferroelectric poly(vinylidene fluoride-co-trifluoroethylene) (PVDF-TrFE) insulator exhibited characteristic source-drain current hysteresis arising from ferroelectric polarization switching of a PVDF-TrFE insulator. Our PS-b-PPP modified rGOs (PMrGOs) with conductive moieties embedded in insulating polymer matrix not only significantly reduced the gate leakage current but also efficiently lowered operation voltage of the device. In consequence, the device showed large memory gate voltage window and high ON/OFF source-drain current ratio with excellent data retention and read/write cycle endurance. Furthermore, our PMrGOs interlayers were successfully employed to FeFETs fabricated on mechanically flexible substrates with promising non-volatile memory performance under repetitive bending deformation.

Charge-transfer dynamics and nonlocal dielectric permittivity tuned with metamaterial structures as solvent analogues

Lee, Kwang Jin,Xiao, Yiming,Woo, Jae Heun,Kim, Eunsun,Kreher, David,Attias, André,-Jean,Mathevet, Fabrice,Ribierre, Jean-Charles,Wu, Jeong Weon,André,, Pascal Nature Publishing Group, a division of Macmillan P 2017 NATURE MATERIALS Vol.16 No.7

<P>Charge transfer (CT) is a fundamental and ubiquitous mechanism in biology, physics and chemistry. Here, we evidence that CT dynamics can be altered by multi-layered hyperbolic metamaterial (HMM) substrates. Taking triphenylene: perylene diimide dyad supramolecular self-assemblies as a model system, we reveal longer-lived CT states in the presence of HMM structures, with both charge separation and recombination characteristic times increased by factors of 2.4 and 1.7-that is, relative variations of 140 and 73%, respectively. To rationalize these experimental results in terms of driving force, we successfully introduce image dipole interactions in Marcus theory. The non-local effect herein demonstrated is directly linked to the number of metal-dielectric pairs, can be formalized in the dielectric permittivity, and is presented as a solid analogue to local solvent polarity effects. This model and extra PH3T:PC60BM results show the generality of this non-local phenomenon and that a wide range of kinetic tailoring opportunities can arise from substrate engineering. This work paves the way toward the design of artificial substrates to control CT dynamics of interest for applications in optoelectronics and chemistry.</P>

Boron difluoride hemicurcuminoid as an efficient far red to near-infrared emitter: toward OLEDs and laser dyes

D'Aleo, A.,Sazzad, M. H.,Kim, D. H.,Choi, E. Y.,Wu, J. W.,Canard, G.,Fages, F.,Ribierre, J. C.,Adachi, C. Royal Society of Chemistry 2017 Chemical communications Vol.53 No.52

A new class of nanostructured supramolecular organic semiconductors based on intertwined multi-lamellar co-assemblies in π-conjugated liquid-crystalline side-chain polymers

Xiao, Yiming,Zeng, Danli,Mazur, Leszek Mateusz,Castiglione, Andrea,Lacaze, Emmanuelle,Heinrich, Benoî,t,Donnio, Bertrand,Kreher, David,Attias, André,-Jean,Ribierre, Jean-Charles,Mathevet, F Nature Publishing Group 2017 Polymer journal Vol.49 No.1

Tuning the Direction of Intramolecular Charge Transfer and the Nature of the Fluorescent State in a T-Shaped Molecular Dyad

Felouat, Abdellah,D’Alé,o, Anthony,Charaf-Eddin, Azzam,Jacquemin, Denis,Le Guennic, Boris,Kim, Eunsun,Lee, Kwang Jin,Woo, Jae Heun,Ribierre, Jean-Charles,Wu, Jeong Weon,Fages, Fré,dé American Chemical Society 2015 The Journal of physical chemistry A Vol.119 No.24

<P>Controlling photoinduced intramolecular charge transfer at the molecular scale is key to the development of molecular devices for nanooptoelectronics. Here, we describe the design, synthesis, electronic characterization, and photophysical properties of two electron donor–acceptor molecular systems that consist of tolane and BF<SUB>2</SUB>-containing curcuminoid chromophoric subunits connected in a T-shaped arrangement. The two π-conjugated segments intersect at the electron acceptor dioxaborine core. From steady-state electronic absorption and fluorescence emission, we find that the photophysics of the dialkylamino-substituted analogue is governed by the occurrence of two closely lying excited states. From DFT calculations, we show that excitation in either of these two states results in a distinct shift of the electron density, whether it occurs along the curcuminoid or tolane moiety. Femtosecond transient absorption spectroscopy confirmed these findings. As a consequence, the nature of the emitting state and the photophysical properties are strongly dependent on solvent polarity. Moreover, these characteristics can also be switched by protonation or complexation at the nitrogen atom of the amino group. These features set new approaches toward the construction of a three-terminal molecular system in which the lateral branch would transduce a change of electronic state and ultimately control charge transport in a molecular-scale device.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpcafh/2015/jpcafh.2015.119.issue-24/acs.jpca.5b03699/production/images/medium/jp-2015-03699g_0001.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jp5b03699'>ACS Electronic Supporting Info</A></P>