Energetics and Raman spectroscopy of organic molecules encapsulated in single-walled boron nitride nanotubes: The example of π-conjugated oligothiophenes

The instability of organic electronic devices under environmental conditions narrowly related to the unstable aggregate state of organic semiconductors is one key obstacle to practical application. Herein, we highlight a promising strategy to overcome these drawbacks consisting to make use of the hollow space within single-walled boron nitride nanotubes (SWBNNTs). As a prototypical system of organic π-conjugated molecules encapsulated in SWBNNTs, we investigate the energetic stability and Raman spectra of a series of oligothiophene molecules (nT) (n = 2, 4, and 6) inside SWBNNTs through a combination of molecular dynamics (MD), density functional theory (DFT), bond polarisability model (BPM), and spectral moments method (SMM). The structural stability of these nanohybrids are explored initially. The optimal SWBNNTs diameters in which the resulting nanohybrids are stable with either one molecule (nT@SWBNNTs) and two encapsulated molecular chains (nT-nT@SWBNNTs) are computed. Then, the computed Raman spectra of the oligothiophenes and SWBNNTs before and after filling are reported. The energetic stability and the possible appearance or not of charge transfer in such nanohybrids are investigated by attentive analysis of the nanoconfinement effect on Raman features of oligothiophenes and SWBNNTs. The present results provide benchmark theoretical data to efficiently probe the interactions subsisting in such nanohybrids based on SWBNNTs templates that can serve as a new stable component for organic electronic devices.