Advanced Science (Aug 2024)

Lattice Symmetry‐Guided Charge Transport in 2D Supramolecular Polymers Promotes Triplet Formation

  • Ruggero Emmanuele,
  • Hiroaki Sai,
  • Jia‐Shiang Chen,
  • Darien J. Morrow,
  • Luka Đorđević,
  • David J. Gosztola,
  • Saw Wai Hla,
  • Samuel I. Stupp,
  • Xuedan Ma

DOI
https://doi.org/10.1002/advs.202402932
Journal volume & issue
Vol. 11, no. 30
pp. n/a – n/a

Abstract

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Abstract Singlet‐to‐triplet intersystem crossing (ISC) in organic molecules is intimately connected with their geometries: by modifying the molecular shape, symmetry selection rules pertaining to spin‐orbit coupling can be partially relieved, leading to extra matrix elements for increased ISC. As an analog to this molecular design concept, the study finds that the lattice symmetry of supramolecular polymers also defines their triplet formation efficiencies. A supramolecular polymer self‐assembled from weakly interacting molecules is considered. Its 2D oblique unit cell effectively renders it as a coplanar array of 1D molecular columns weakly bound to each other. Using momentum‐resolved photoluminescence imaging in combination with Monte Carlo simulations, the study found that photogenerated charge carriers in the supramolecular polymer predominantly recombine as spin‐uncorrelated carrier pairs through inter‐column charge transfer states. This lattice‐defined recombination pathway leads to a substantial triplet formation efficiency (≈60%) in the supramolecular polymer. These findings suggest that lattice symmetry of micro‐/macroscopic structures relying on intermolecular interactions can be strategized for controlled triplet formation.

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