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Highly Ordered 2D-Assemblies of Phase-Segregated Block Molecules for Upconverted Linearly Polarized Emission.

Martin H C van SonAnton M BerghuisFabian EisenreichBas de WaalGhislaine VantommeJaime Gómez RivasE W Meijer
Published in: Advanced materials (Deerfield Beach, Fla.) (2020)
Materials based on the laminar ordering of self-assembled molecules have a unique potential for applications requiring efficient energy migration through densely packed chromophores. Here, employing molecular assemblies of coil-rod-coil block molecules for triplet-triplet annihilation upconversion (TTA-UC) based on triplet energy migration with linearly polarized emission is reported. By covalently attaching discrete-length oligodimethylsiloxane (oDMS) to 9,10-diphenylanthracene (DPA), highly ordered 2D crystalline DPA sheets separated by oDMS layers are obtained. Transparent films of this material doped with small amounts of triplet sensitizer PtII octaethylporphyrin show air-stable TTA-UC under non-coherent excitation. Upon annealing, an increase in TTA-UC up to two orders of magnitude is observed originating from both an improved molecular ordering of DPA and an increased dispersion of the sensitizer. The molecular alignment in millimeter-sized domains leads to upconverted linearly polarized emission without alignment layers. By using a novel technique, upconversion imaging microscopy, the TTA-UC intensity is spatially resolved on a micrometer scale to visually demonstrate the importance of molecular dispersion of sensitizer molecules for efficient TTA-UC. The reported results are promising for anti-counterfeiting and 3D night-vision applications, but also exemplify the potential of discrete oligodimethylsiloxane functionalized chromophores for highly aligned and densely packed molecular materials.
Keyphrases
  • energy transfer
  • high resolution
  • quantum dots
  • photodynamic therapy
  • high throughput
  • risk assessment
  • optical coherence tomography
  • single cell
  • human health
  • ionic liquid
  • molecularly imprinted