Fig. 2: Cation–side chain interaction prediction.
From: A thermally activated and highly miscible dopant for n-type organic thermoelectrics
a Chemical structures of FBDPPV anions, TAM+, and N-DMBI+ cations. b Schematic diagram of initial supercell for molecular dynamics which contains FBDPPV anions and TAM+ (or N-DMBI+) cations. Polymer alkyl chains are hidden for clearer vision. c, d Equilibrium configurations of n-doped FBDPPV by TAM (c) or N-DMBI (d). The middle (fourth of six) π–π stacking layer is highlighted for clearer vision. e, f Histogram of distances between dopant cations and polymer-conjugated backbones for TAM-doped FBDPPV (e) and N-DMBI-doped FBDPPV (f). Notice distance = 0 is polymer backbone and distance = 25 Å is alkyl chain tails. In all the above schematic diagrams, light green is for FBDPPV backbone, orange is for FBDPPV alkyl side chain, and red/blue is for dopant cation. TAM+ cation has distinctly weaker interactions with polymer backbones, whereas N-DMBI+ cation presents stronger interactions with polymer backbones.
