Flat-on ambipolar triphenylamine/C60 nano-stacks formed from the self-organization of a pyramid-sphere-shaped amphiphile

Abstract

A giant amphiphile, which is constructed with an amorphous nano-pyramid (triphenylamine, TPA) and a crystalline nano-sphere (C60), was synthesized. Structural characterization indicates that this pyramid-sphere-shaped amphiphile (TPA-C60) forms a solvent-induced ordered phase, in which the two constituent units self-assemble into alternating stacks of two-dimensional (2D) TPA and C60 nano-sheets. Due to the complexity of the molecular structure and the amorphous nature of the nano-pyramid, phase formation was driven by intermolecular C60-C60 interactions and the ordered phase could not be reformed from the TPA-C60 melt. Oriented crystal arrays of TPA-C60, which contain flat-on TPA/C60 nano-stacks, can be obtained via a PDMS-assisted crystallization (PAC) technique. The flat-on dual-channel supramolecular structure of TPA-C60 delivered ambipolar and balanced charge-transport characteristics with an average μe of 2.11 × 10-4 cm2 V-1 s-1 and μh of 3.37 × 10-4 cm2 V-1 s-1. The anisotropic charge-transport ability of the pyramid-sphere-shaped amphiphile was further understood based on the lattice structure and the lattice orientation of TPA-C60 revealed from electron diffraction analyses.