Real-time observation of conformational switching in single conjugated polymer chains

Abstract

Single-molecule experiments in organic solvents provide new insight into the conformational dynamics of conjugated polymers.

Single-Molecule Spectroscopy of Polyfluorene Chains Reveals β-Phase Content and Phase Reversibility in Organic Solvents

“…We recently introduced an immobilization method for poly(3-hexylthiophene) (P3HT) using triethoxysilane (TES) groups. 35 Here, we developed a synthetic route to incorporate TES functionalities at a single end of the PFO polymer.…”

“…The glass substrates containing dispersed PFO chains were then placed in a custom-built chamber that was later filled with a specific solvent for imaging (see the Supplemental Information for details of the setup and sample chamber). 35 In our single-molecule setup, the field-of-view (FOV) has dimensions of 50 3 50 mm. In a typical experiment, 200-300 spots, each corresponding to a single molecule, can be observed in the FOV, which has an area of 2,500 mm 2 , corresponding to a density of 8.3 mm 2 per molecule ( Figure 1).…”

“…In our previous work, we demonstrated specific immobilization of P3HT polymers using silane chemistry with no need to passivate the glass surface. 35 However, the intrinsically weak non-specific adsorption of P3HT chains to bare glass substrates constitutes an exception. Most widely used CPs exhibit strong non-specific interactions with the glass surface that can alter their conformation and preclude the immobilization of single chains at one specific end.…”

Fluctuations in the Emission Polarization and Spectrum in Single Chains of a Common Conjugated Polymer for Organic Photovoltaics

“…This conclusion is evidence of the power of this technique to understand the complex arrangement and aggregation of conjugated polymers. Much work has been expended on investigating the electronic, physical, and morphological arrangement of many conjugated polymers including poly(p‐phenylene vinylene)‐based materials and poly(3‐hexylthiophene) . What emerges from these studies is that even at the single chain level, the spatial‐energetic arrangement of chains is not always well understood.…”

“…Much work has been expended on investigating the electronic, physical, and morphological arrangement of many conjugated polymers including poly(p-phenylene vinylene)-based materials [33,34,[37][38][39][40][41][42][43][44][45][46] and poly(3-hexylthiophene). [47][48][49][50][51][52] What emerges from these studies is that even at the single chain level, the spatial-energetic arrangement of chains is not always well understood. This question is of strong relevance for new low bandgap conjugated polymers used in OPVs, where such material arrangements can be crucial to photovoltaic performance, with single molecule studies now helping to understand the photophysics and spatial organization of materials such as PTB7 [18] and PCDTBT.…”