Cationic polaron delocalization in porphyrin nanoribbons

This is the authors' abstract. We don't add key points for this paper.

Long-range delocalization of unpaired electrons in organic π-conjugated oligomers is an important requirement to achieve high charge carrier mobilities in molecular transistors. We have investigated the polaron delocalization in the radical cations of a series of β,meso,β-edge-fused porphyrin oligomers consisting of up to 18 porphyrin units by a combination of cw-EPR, 1H, and 14N electron-nuclear double resonance (ENDOR), 14N hyperfine sublevel correlation (HYSCORE), and vis-NIR-MIR spectroscopy, supported by density functional theory (DFT) calculations and simulations. The results demonstrate coherent delocalization of the radical cation over more than 10 porphyrin units, which corresponds to an effective coherence length >8.5 nm. We discovered a remarkably non-uniform distribution of the radical spin density and an increase in phase memory time with increasing delocalization length (up to Tm ≈ 4 μs at 50 K). This study opens new avenues toward the design of molecular electronic and spintronic materials.