Contributors: Laboratoire Photonique, Numérique et Nanosciences (LP2N); Université de Bordeaux (UB)-Institut d'Optique Graduate School (IOGS)-Centre National de la Recherche Scientifique (CNRS); École Polytechnique de Montréal (EPM); Université Paris Saclay, ONERA, CNRS, Laboratoire d'étude des microstructures (LEM); ONERA-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS); Centre interuniversitaire de recherche et d'ingénierie des matériaux (CIRIMAT); Université Toulouse III - Paul Sabatier (UT3); Communauté d'universités et établissements de Toulouse (Comue de Toulouse)-Communauté d'universités et établissements de Toulouse (Comue de Toulouse)-Institut Universitaire de Technologie - Paul Sabatier (IUT Toulouse Auch Castres); Communauté d'universités et établissements de Toulouse (Comue de Toulouse)-Communauté d'universités et établissements de Toulouse (Comue de Toulouse)-Institut de Chimie - CNRS Chimie (INC-CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP); Communauté d'universités et établissements de Toulouse (Comue de Toulouse); Laboratoire Charles Coulomb (L2C); Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM); Université de Montréal (UdeM); ANR-17-CE18-0026,Parkington,Validation translationnelle des greffes d'organoïdes neuraux pour le traitement des maladies de Parkinson et de Huntington(2017); ANR-21-CE45-0028,MOLIERE,Model Of coLon epIthElial aRchitecturE(2021)
Abstract: International audience ; Polarized fluorescence emission of nanoscale emitters has been extensively studied for applications such as bioimaging, display, and optical communication. Extending the polarization properties in large assemblies of compact emitters is, however, challenging because of self-aggregation processes, which can induce depolarization effects, quenching, and cancellations of molecular dipoles. Here we use a-sexithiophene (6T) molecules confined inside boron nitride nanotubes (6T@BNNTs) to induce fluorescence anisotropy in a transparent host. The experiments first indicate that individual 6T@BNNTs exhibit a high polarization extinction ratio, up to 700, at room temperature. Using aberration- corrected HRTEM, we show that the fluorescence anisotropy is consistent with a general alignment of encapsulated 6T molecules along the nanotube axis. The molecular alignment is weakly influenced by the nanotube diameter, a phenomenon ascribed to stronger molecule-to-sidewall interactions compared to intermolecular interactions. By stretching a flexible thin film made of transparent polymers mixed with 6T@BNNTs, we induce a macroscopic fluorescence anisotropy within the film. This work demonstrates that the dyes@BNNT system can be used as an easy-to-handle platform to induce fluorescence anisotropy in photonic materials.
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