SCIENTIFIC HIGHLIGHTS

Homoconjugation in Light-Emitting Poly(phenylene methylene)s: Origin and Pressure-Enhanced Photoluminescence
29 December 2020
The surprising optical properties of the non-π-conjugated polymer poly(phenylene methylene) (PPM) and its derivatives—that is, absorption in the 350–450 nm and photoluminescence (PL) in the 400–600 nm spectral regions—have been attributed to chromophores formed by homoconjugation along the polymer chain. The enabling role of homoconjugation, however, was hitherto ascertained primarily by excluding alternative origins of luminescence.

The present study offers direct evidence for homoconjugation by employing optical and vibrational spectroscopy to investigate the interplay between the microstructure and solid-state optical properties of PPM and its derivative poly(2,4,6-trimethylphenylene methylene). In particular, polarized Raman and PL spectroscopy of melt-drawn fibers reveal a preferentially perpendicular orientation of the phenylene rings relative to the fiber axis and, simultaneously, a preferentially parallel orientation of the transition dipole moment. PL spectroscopy under applied hydrostatic pressure yields a nearly fourfold increase in PL intensity at 8 GPa, together with a surprising absence of excimer emission. These characteristics, being highly atypical of conventional π-conjugated polymers, highlight the different origin of the optical properties of PPMs and unique opportunities for applications.

 

Hits: 557
Sustainable energy conversion & storage systems

Homoconjugation in Light-Emitting Poly(phenylene methylene)s: Origin and Pressure-Enhanced Photoluminescence


Aleksandr Perevedentsev*, Adrián Francisco-López, Xingyuan Shi, Andreas Braendle, Walter R. Caseri, Alejandro R. Goñi, and Mariano Campoy-Quiles

Macromolecules 2020, 53, 17, 7519–7527
Publication DateAugust 26, 2020 
DOI: https://doi.org/10.1021/acs.macromol.0c01153

Also at ICMAB

  • Accelerating organic solar cell material's discovery: high-throughput screening and big data

    Information
    11 June 2021 201 hit(s) Energy
    The discovery of novel high-performing materials such as non-fullerene acceptors and low band gap donor polymers underlines the steady increase of record efficiencies in organic solar cells witnessed during the past years. Nowadays, the resulting catalogue of organic photovoltaic materials is becoming unaffordably vast to be evaluated following classical experimentation methodologies: their requirements in terms of human workforce time and resources are prohibitively high, which slows momentum to the evolution of the organic photovoltaic technology.
  • Boost of Charge Storage Performance of Graphene Nanowall Electrodes by Laser-Induced Crystallization of Metal Oxide Nanostructures

    Information
    08 June 2021 201 hit(s) Energy
    Major research efforts are being carried out for the technological advancement to an energetically sustainable society. However, for the full commercial integration of electrochemical energy storage devices, not only materials with higher performance should be designed and manufactured but also more competitive production techniques need to be developed.
  • Unveiling Planar Defects in Hexagonal Group IV Materials

    Information
    01 June 2021 243 hit(s) Energy
    Recently synthesized hexagonal group IV materials are a promising platform to realize efficient light emission that is closely integrated with electronics. A high crystal quality is essential to assess the intrinsic electronic and optical properties of these materials unaffected by structural defects. Here, we identify a previously unknown partial planar defect in materials with a type I3 basal stacking fault and investigate its structural and electronic properties.
  • Battery Materials Design Essentials

    Information
    21 May 2021 363 hit(s) Energy
    The advanced materials industry is one of the leading technology sectors worldwide. The development of such materials is at the core of the technological innovations and has been possible in the last century thanks to the transition from “observational” science to “control” science.
  • Study of nanostructured ultra-refractory Tantalum-Hafnium-Carbide electrodes with wide electrochemical stability window

    Information
    04 May 2021 303 hit(s) Energy
    Transition metal carbides have gathered increasing attention in energy and electrochemistry applications, mainly due to their high structural and physicochemical properties. Their high refractory properties have made them an ideal candidate coating technology and more recently their electronic similarity to the platinum group has expanded their use to energy and catalysis. Here, we demonstrate that the nanostructuring and stoichiometry control of the highest melting point material to this date (Ta-Hf-C) results in outstanding electrochemical stability.

INSTITUT DE CIÈNCIA DE MATERIALS DE BARCELONA, Copyright © 2020 ICMAB-CSIC | Privacy Policy | This email address is being protected from spambots. You need JavaScript enabled to view it.