Reversible holography and optical phase conjugation for image formation/correction using highly efficient organic photorefractive polymers

AbstractIn this work, we report the reversible reconstruction of holographic and distorted transmission images through the four wave mixing (FWM) technique and optical phase conjugation (OPC), an alternative method to adaptive optics, by using highly efficient Photorefractive (PR) polymers fabricated in our laboratories. These PR polymers are based on our synthesized nonlinear chromophore 4-[4-(diethylamino)-2 hydroxybenzylideneamino] benzonitrile (Dc). For the PR devices, diffraction efficiencies as high as 90% at 25wt.% doping level of Dc at an external applied electric field (Eext) around 56V/μm are achieved. The reconstruction implementation is simple, of low cost, all-optical and it is capable of recovering 90% of the original images. The real-time holographic experiments were performed at Eext of just 27V/μm, which is one of the lowest reported values. Reversible holographic imaging is showed with a rise-time around 0.35s

Interacciones semióticas entre el diseño, el arte y la cultura

260 páginasSe expone la forma en la que, el arte, el diseño y la cultura encontraron convergencia en el planteamiento de los estudios actuales sobre la semiótica de la imagen. En sus capítulos se muestran caminos en donde el signo, la significación y el sentido se entretejen como parte de la semiótica de la cultura, de la representación simbólica y la intertextualidad, buscando enriquecer el estudio del funcionamiento y operación de los procesos de significación, desde una visión donde la interdisciplinariedad se expone como el eje que orienta la interacción de los signos que son objeto de este volumen. Los diferentes puntos de vista aquí reunidos han sido estructurados en tres secciones, tituladas: abordajes semióticos, imágenes y representaciones y el juego de los signos, en donde se hace patente la relevancia de realizar aproximaciones interdisciplinarias que sirven para analizar los procesos culturales como fenómenos sígnicos articulados, los cuales trascienden a la esfera antropológica.María Teresa Olalde Ramos; Claudia Fragoso Susunaga; Olivia Fragoso Susunaga; Consuelo Córdoba Flores, coordinadora

Photophysical Study of Polymer-Based Solar Cells with an Organo-Boron Molecule in the Active Layer

Our group previously reported the synthesis of four polythiophene derivatives (P1–P4) used for solar cells. The cells were prepared under room conditions by spin coating, leading to low efficiencies. However, after the addition of 6-nitro-3-(E)-3-(4-dimethylaminophenyl)allylidene)-2,3-dihydrobenzo[d]-[1,3,2] oxazaborole (M1) to their active layers, the efficiencies of the cells showed approximately a two-fold improvement. In this paper, we study this enhancement mechanism by performing ultrafast transient absorption (TA) experiments on the active layer of the different cells. Our samples consisted of thin films of a mixture of PC61BM with the polythiophenes derivatives P1–P4. We prepared two versions of each sample, one including the molecule M1 and another without it. The TA data suggests that the efficiency improvement after addition of M1 is due not only to an extended absorption spectrum towards the infrared region causing a larger population of excitons but also to the possible creation of additional channels for transport of excitons and/or electrons to the PC61BM interface

Nano-films of carbo-benzene derivatives: Scanning probe microscopy analysis and prospects of use in organic solar cells

International audienceThree carbo-mer derivatives based on a C18Ph4 core decorated with two identical electro-active groups X, i.e. two aromatic carbo-benzenes (1 and 2, X = 4-anilinyl) and one pro-aromatic carbo-quinoid (the carbo-TTF 3, X = 1,3-dithiol-2-ylidene) were studied through Scanning Probe Microscopies (SPMs). Self-Assembled Monolayers (SAMs) were fabricated (thickness ~160 pm), for the two centrosymmetric representatives 1 and 3, the organization of which on the HOPG substrate was found to be structure-specific. Electrical/electronic properties of the three carbo-mers were determined by using Atomic Force Microscopy (AFM) and its electrical modes: Kelvin Probe Force Microscopy (KPFM) and conductive Atomic Force Microscopy (c-AFM). Measurements of the work function (∅) through KPFM result in a ∅ = 5.60 eV value for 1, 4.97 eV for 2 and 4.82 eV for 3. Hole mobility (µ) values extracted from local I-V plots by using c-AFM are 15×10- 8cm2V- 1s- 1 for 1, 3×10- 6cm2V-1s-1 for 2 and 87×10- 8cm2V- 1s- 1 for 3. A concept test of the possible application of carbo-mers in self-assembled hole transporting monolayer (SA-HTM), with the view to replacing the most common p-type contact used in organic solar cells (OSCs), PEDOT:PSS, is also reported

Light Emission Properties of a Cross-Conjugated Fluorene Polymer: Demonstration of Its Use in Electro-Luminescence and Lasing Devices

Light emission properties of a fluorene cross-conjugated polymer (PF–1) based on the monomer 4,7-bis[2-(9,9-dimethyl)fluorenyl] benzo[1,2,5]thiadiazole are reported. This polymer exhibits solubility at high concentrations, good processability into thin solid films of good quality and a broad emission band with a fluorescence quantum yield of approximately 1. Based on these features, in this paper we implemented the use of PF–1 as an active layer in polymer light-emitting diodes (PLEDs) and as a laser gain medium in solution. To get insight on the conducting properties of PF–1, two different electron injectors, poly [(9,9-bis(3′-(N,N-dimethylamino) propyl)-2,7-fluorene)-alt-2,7-(9,9–dioctylfluorene)] (PFN) and lithium fluoride (LiF), were used in a simple PLED architecture. PLEDs with the PFN film were found to exhibit better performance with a maximum luminous efficiency of 40 cd/A, a turn-on voltage (Von) of approximately 4.5 V and a luminance maximum of 878 cd/m2 at 5.5 V, with a current density of 20 A/m2. For the lasing properties of PF–1, we found a lasing threshold of around 75 μJ and a tunability of 20 nm. These values are comparable with those of rhodamine 6G, a well-known laser dye

Dendrimers Containing Ferrocene and Porphyrin Moieties: Synthesis and Cubic Non-Linear Optical Behavior

Dendrons with ferrocenyl ended groups joined by styryl moieties were attached to a porphyrin core. All the dendrons used for dendrimer synthesis showed trans configuration. The chemical structure of the first generation dendron was confirmed by X-ray crystallographic studies. The structure of the synthesized dendrimers was confirmed by 1H- and 13C-NMR, electrospray mass spectrometry and elemental analysis. Cubic non-linear optical behavior of the ferrocene and porphyrin-containing dendrimers was studied in solid thin films by THG Maker-Fringe technique at 1,260 nm

Expanding the carbo ‐Benzene Chemical Space for Electron‐Accepting Ability: Trifluorotolyl/Tertiobutyl Substitution Balance

International audienceWith the view to altering the lipophilicity and electron accepting ability of the tetraphenyl-carbo-benzene scaffold, peripheral fluorination of the C18 ring through aromatic linkers was envisaged from the C18Ph6 and o-tBu2C18Ph4 references, by replacement of two Ph substituents with two p-CF3-C6H4 counterparts (FTol). The synthesis relied on a [8+10] macrocyclization involving a common bis(trifluorotolyl)-tetraynedione, followed by reductive aromatization of the resulting [6]pericyclynediols. While p-FTol2C18Ph4 proved to be hardly tractable due to an extremely low solubility, p-FTol2-o-tBu2C18Ph2 could be extensively studied by X-ray crystallography, NMR and UV/Vis spectroscopy, voltammetry, STM imaging of monolayers, and AFM imaging of binary films with P3HT or PC71BM fabricated by spin-coating for organic photovoltaic cells and J−V curve measurement thereof. The electronic and polarity properties are correlated with moderate but consistent electron-withdrawing effects of the CF3 groups, in agreement with the DFT-calculated frontier orbitals and multipole moments. The results provide guidelines for optimization of fluorinated carbo-benzene targets