Highly Polarized Light Emission from 6T@BNNT Nanohybrids

TL;DR

This study demonstrates that Boron Nitride Nanotubes can align encapsulated organic molecules, producing highly polarized light emission with potential applications in photonics and bio-imaging.

Contribution

The paper introduces a novel nanohybrid system where BNNTs serve as templates to align encapsulated 6T molecules, achieving high polarization ratios and controlled molecular orientation.

Findings

Fluorescence from 6T@BNNT hybrids is strongly polarized with high extinction ratios.

Most encapsulated 6T molecules align within 10° of the BNNT axis.

Over 80% of molecules show a preferred orientation along the BNNT axis.

Abstract

The polarized fluorescence emission of organic fluorophores has been extensively studied in photonics and is increasingly exploited in single molecule scale bio-imaging. Expanding the polarization properties of compact molecular assemblies is, however, extremely challenging due to depolarization and quenching effects associated with the self-aggregation of molecules into the sub-nanometer scale. Here we demonstrate that Boron Nitride Nanotubes (BNNTs) can act as a 1D host-template for the alignment of encapsulated a-sexithiophene (6T) inside BNNTs, leading to an optically active 6T@BNNT nanohybrid. We show that the fluorescence from the nanohybrid is strongly polarized with extinction ratios as high as 700 at room temperature. A statistical analysis of the 6T orientation inside BNNTs with inner diameter up to 1.5 nm shows that at least 80% of the encapsulated 6Ts exhibit a maximum deviation angle of less than 10{\deg} with respect to the BNNT axis. Despite a competition between molecule-molecule and molecule-BNNT adsorption in larger BNNTs, our results also show that more than 80% of the molecules display a preferential orientation along the BNNT axis with a deviation angle below 45{\deg}.